Hybrid Coronary Revascularization - pediagenosis
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Thursday, November 21, 2019

Hybrid Coronary Revascularization

Hybrid Coronary Revascularization
Hybrid coronary revascularization (HCR) is defined as the combination of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) to treat multivessel coronary artery disease. HCR most commonly combines a minimally invasive CABG procedure involving a left internal thoracic artery (LITA) to the left anterior descending coronary artery (LAD) anastomosis with PCI to non-LAD vessels. This technique offers and combines the advantages of both surgical and percutaneous revascularlization, eliminating at the same time the disadvantages.

Definition and Rationale
·  Hybrid coronary revascularization (HCR) is defined as the combination of coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI) to treat multivessel coronary artery disease (CAD). HCR most commonly combines a minimally invasive CABG procedure involving a left internal thoracic artery (LITA) to the left anterior descending coronary artery (LAD) anastomosis with PCI to non-LAD vessels. This technique offers and combines the advantages of surgical and percutaneous revascularization, eliminating at the same time the disadvantages of both procedures. In fact, this evolving revascularization technique uses the survival benefits conferred by the LITA to LAD graft while providing the patient with complete and minimally invasive coronary artery revascularization with PCI to the non-LAD vessels. The sequence and timing of the surgical and interventional components of hybrid therapy can be in three different ways: PCI first followed by surgery, surgery followed by PCI (two-stage HCR), or both carried out during the same setting (single-stage HCR). In the era of primary PCI for ST-segment elevation myocardial infarction (MI), it is probable that patients requiring immediate PCI of the right coronary artery (RCA) or circumflex artery as the culprit lesion may require subsequent surgical revascularization of a complex LAD or left main lesion at some time in the future. Hence, HCR, by definition, generally refers to a revascularization strategy that has been strategically planned in a coordinated fashion by interventional cardiologists and cardiac surgeons.
·   The optimal revascularization strategy for multivessel CAD is still debated. Although there are survival benefits of complete arterial coronary revascularization, in practice only a fraction of patients referred for CABG actually receive this; most of them receive at least one saphenous vein graft (SVG). If it is true that recent trials, including SYNTAX,1 have helped establish which anatomic categories are best addressed with traditional CABG versus multivessel PCI with a drug-eluting stent (DES), it is also true that there is still potential for prognostic and symptomatic improvement from coronary revascularization in certain patients with multivessel CAD. The modality depends on many factors, the most important of which is the coronary anatomy itself. Other crucial factors include the clinical setting (e.g., emergent, acute, chronic); left ventricular function; degree of myocardial viability; and presence or absence of comorbidities, assessed through the risk score of the Society of Thoracic Surgeons (STS) or EuroScore (e.g., diabetes, associated valvular heart disease, presence of calcification of the ascending aorta, which could preclude safe cross-clamping during surgical intervention, age, patient preference, availability of bypass conduits). Outcomes in diabetic patients, in particular, seem to favor a surgical strategy over PCI for multivessel disease, although first-generation sirolimus-eluting and paclitaxel-eluting stents were the predominant types of DESs used in the FREEDOM trial and may underestimate the benefits of current (third-generation) stenting.2
·    However, CABG is still considered the gold standard treatment for patients with multivessel CAD.3-5 The major therapeutic benefits of CABG arise from the graft of the LITA to LAD, which has been shown to have excellent long-term results in terms of patency, event-free survival, and relief of angina.6,7 On the other hand, SVGs have shown a high incidence of failure8 as opposed to multivessel PCI with a DES, which has shown lower restenosis rates, lower failure rates than SVG, and lower stroke rates compared with CABG. In addition, PCI is less invasive and has a shorter recovery time.9,10 HCR thus represents a promising coronary revascularization option due to the fact that it offers the advantages of the best of both treatment options. It takes advantage of the survival benefit conferred by the LITA to LAD graft while minimizing the invasiveness of revascularization therapy and providing a complete revascularization with PCI to the non-LAD vessels. Additionally, the use of the robotic-assisted, coronary artery bypass grafting (RA-CABG) graft of the LITA to the LAD minimizes surgical trauma further.
·    Several studies have already demonstrated similar results in terms of mortality, patency, and major adverse cardiac event rates—between a hybrid revascularization strategy and similar conventional on- and off-pump coronary bypass surgery.11-14 However, the safety and effectiveness of HCR is still understudied and further studies, especially randomized trials, are necessary before stronger recommendations can be made for this revascularization therapy.

History of Hybrid Coronary Revascularization
·  HCR was first described by Angelini et al. in 1996.15 They used the classic minimally invasive direct coronary artery bypass (MIDCAB) procedure, in which the LITA is harvested by direct vision through a fourth interspace left minithoracotomy; the LITA is sutured to the LAD on the beating heart. After the pioneering work of Benetti et al.16 on minimally invasive CABG, MIDCAB was adopted by several groups in the mid-1990s.17-20 HCR then evolved as a result of the desire to treat patients with multivessel disease effectively while at the same time lowering procedure-related morbidity by combining minimal access coronary artery surgery with percutaneous techniques.
· This was a very innovative and visionary new concept in the field of coronary revascularization, representing a mix and the natural evolution of the two disciplines, cardiac surgery and interventional cardiology. Interventional cardiologists were progressively more aggressive in their percutaneous treatment of CAD; surgeons were developing minimally invasive techniques with a smaller incision, avoidance of sternotomy, and beating heart surgery technique. Additionally, throughout the 1990s, endoscopic, video-assisted, and finally robot-assisted LITA dissection were performed. Successful endoscopic harvesting of LITA has been a crucial step in the performance of minimal access coronary artery bypass surgery through minithoracotomy incisions,21 and video-assisted LITA takedown has been further facilitated by the use of robotic assistance. In the last 15 years, telemanipulation surgical systems have significantly improved, and currently RA-CABG encompasses the use of robotic assistance to varying degrees, from robotic-assisted LITA harvest to manual anastomosis through a mini anterior non-rib spreading incision procedures to total endoscopic coronary artery bypass (TECAB). On the other hand, there has been a continuous improvement of DES performance and, in low-risk patients and those with single-vessel disease, PCI can now provide comparable short- and mid-term outcomes to those of CABG.22,23

Indications for Hybrid Coronary Revascularization and Patient Selection
·    According to the 2011 American College of Cardiology/American Heart Association guidelines for CABG,24 HCR is a suitable coronary revascularization strategy for patients with multivessel CAD (e.g., LAD and one or more non-LAD stenoses) and an indication for revascularization:
Hybrid revascularization is ideal in patients in whom technical or anatomic limitations to CABG or PCI alone may be present and for whom minimizing the invasiveness (and therefore the risk of morbidity and mortality) of surgical intervention is preferred (e.g., patients with severe preexisting comorbidities, recent MI, a lack of suitable graft conduits, a heavily calcified ascending aorta, or a non-LAD coronary artery unsuitable for bypass but amenable to PCI, and situations in which PCI of the LAD artery is not feasible because of excessive tortuosity or chronic total occlusion).

1. Recommendations From 2011 American College of Cardiology/American Heart Association Guidelines for Coronary Artery Bypass Surgery24
Class IIa
HCR, defined as the planned combination of LITA to LAD artery grafting and PCI of one or more non-LAD coronary arteries, is reasonable in patients with one or more of the following (level of evidence: B):
  Limitations to traditional CABG, such as heavily calcified proximal aorta or poor target vessels for CABG (but amenable to PCI).
    Lack of suitable graft conduits.
    Unfavorable LAD artery for PCI (i.e., excessive vessel tortuosity or chronic total occlusion).

Class IIb
    HCR, defined as the planned combination of LITA to LAD artery grafting and PCI of one or more non-LAD coronary arteries, may be reasonable as an alternative to multivessel PCI or CABG in an attempt to improve the overall risk-benefit ratio of the procedures (level of evidence: C). According to the 2014 European Society of Cardiology/European Association for Cardio-Thoracic Surgery guidelines on myocardial revascularization25:
Hybrid procedures consisting of LITA to LAD and PCI of other territories appear reasonable when PCI of the LAD is not an option or is unlikely to portend good long-term results or when achieving a complete revascularization during CABG might be associated with an increased surgical risk.
    HCR may be clinically indicated in the following cases25:
1.   Select patients with single-vessel disease of the LAD, or in those with multivessel disease but with poor surgical targets, except for the LAD territory, in whom minimally invasive surgery can be performed to graft the LAD using the LITA. The remaining lesions in other are subsequently treated by PCI.
2.   Patients who had previous CABG and now require valve surgery and who have at least one important patent graft (e.g., LITA to LAD) and one or two occluded grafts with a native vessel suitable for PCI.
3.  Combination of revascularization with nonsternotomy valve intervention (e.g., PCI and minimally invasive mitral valve repair, or PCI and transapical aortic valve implantation).
In addition, some patients with complex multivessel disease presenting with STEMI initially require primary PCI of the culprit vessel, but subsequently may require complete surgical revascularization. A similar situation occurs when patients with combined valvular and CAD require urgent revascularization with PCI. Finally, when a heavily calcified aorta is found in the operating room, the surgeon may elect not to attempt complete revascularization and to offer delayed PCI.25
    In the Canadian Cardiovascular Society/Canadian Association of Interventional Cardiology/ Canadian Society of Cardiac Surgery Position Statement on Revascularization—Multivessel Coronary Artery Disease,26 it is stated that HCR:
1.    Is typically performed with minimally invasive incisions.
2.    Combines the advantage of the LITA to LAD graft with the less invasive nature of PCI.
3.  Has been demonstrated by studies to date to be safe and effective, but definitive data (e.g., randomized trials) are lacking.
    However, the lack of randomized controlled clinical trials does not allow the identification of an HCR target group of patients. Therefore, HCR should be considered an alternative treatment strategy that should be tailored to the individual patient based on the patient’s anatomy and patient-related variables through a collaborative heart team approach. The ideal patient is a patient with multivessel CAD, with a complex proximal LAD lesion suitable for LITA-LAD grafting, associated with non-LAD lesions suitable for PCI, and no contraindications for dual antiplatelet therapy (Fig. 6.1). Careful attention should be focused on the quality and size of the LAD, epicardial or intramyocardial LAD course (Fig. 6.2), presence of large diagonal vessels, which can be mistaken as the LAD and inadvertently grafted, complexity of non-LAD vessel lesions for PCI, and number of stents necessary to treat the non-LAD stenosis effectively. PCI of overly complex non-LAD vessels (e.g., long lesions, bifurcations of major branches) will increase the risk of restenosis and may diminish the benefits of a percutaneous strategy over saphenous vein or other arterial grafting.
    Other important factors in patient selection for HCR are patient variables, including clinical presentation, comorbidities, body habitus, chest wall anatomy, and surgeon experience with minimally invasive CABG procedures. Chest wall anatomy, obesity, and thoracic size may have a significant impact on the surgical part of the procedure. Patient comorbidities, such as chronic obstructive pulmonary disease and pulmonary hypertension, also have a significant impact. For a robotic-assisted approach, the patient must be able to tolerate single-lung ventilation and physiologic changes related to carbon dioxide insufflation. HCR could then serve patients at the two extremities of the risk spectrum young and relatively healthy patients who prefer to avoid the sternotomy but do not want to renounce the durability of the LITA- LAD graft, and older and/or high-risk patients who may benefit from a less traumatic, minimally invasive but full and complete coronary revascularization. In the end, it is quite intuitive that the experience of the surgeon is a key factor in the successful outcome of this revascularization strategy, given the challenging nature and steep learning curve of the minimally invasive CABG techniques (from RA-CABG to TECAB).
Figure 6.1 This coronary angiogram shows an example of an ideal candidate for hybrid coronary revascularization. (A) Focal lesion of the circumflex artery. (B) Complex, tandem lesion of the left anterior descending coronary artery. (C) Focal lesion of the right coronary artery.

Figure 6.2 The arrow indicates the epicardial course of the left anterior descending coronary artery.

Methods and Techniques
2. Procedural Stages
Single-Stage Procedure
·  A minimally invasive coronary artery bypass procedure is done first (Fig. 6.3). The patient remains on aspirin preoperatively, intraoperatively, and postoperatively. After harvest of the LITA, bivalirudin at a loading dose of 0.75 mg/kg is administered; infusion at a rate of 1.75 mg/kg/hr is continued throughout the rest of the procedure, including the surgical revascularization and PCI. After the surgical revascularization is completed, the hybrid operating room is then reset to a cardiac catheterization configuration. The LITA graft check is performed. After hemostasis is confirmed, with evidence of minimal drainage from chest tubes, clopidogrel, 600 mg, or ticagrelor, 180 mg via a nasogastric (NG) tube, is administered (Fig. 6.4). PCI is performed on non-LAD targets. The bivalirudin infusion is continued and overlapped with the clopidogrel over the next hour. Postoperatively, the patient is continued on aspirin and clopidogrel or ticagrelor.
Two-Stage Procedure
·  If PCI has already been performed on the culprit non-LAD vessel, then after 3 months the clopidrogrel or ticagrelor are held for 2 days prior to the surgery but not the ASA. The dual antiplatelet therapy is restarted the day after surgery. Minimally invasive surgical revascularization is performed as per routine using heparin and protamine for reversal. If PCI is to be performed postoperatively, the evening after surgery the patient is given a loading dose of clopidogrel or ticagrelor; the patient undergoes PCI on the next day. Postoperatively, the patient is continued on aspirin and clopidogrel or ticagrelor.

3. Operative Technique
Anesthesia Considerations
·    A paravertebral or intrathecal block with epimorphine is used for pain control.
·    Defibrillator pads on the left scapula and inferior and medial to the right breast are placed.
·    Intubation is performed with a double-lumen endotracheal tube (ETT) to deflate the left lung.
·  Alternatively, a single-lumen ETT and bronchial blocker may be placed under fiberoptic guidance.
·  Lines are routine; they include an arterial line and pulmonary artery catheter (PAC), if required. If peripheral access is limited, 16-G IV tubing should at least be placed. A triple-lumen catheter is placed if no PAC is inserted.
·  After intubation, place a bronchial blocker into the mainstream bronchus with fiberoptic guidance. Place the proximal end of the balloon approximately 1 to 2 cm below the carina.
·    A warming blanket should be used to avoid hypothermia.
·    CO2 insufflation is provided to maintain an intrathoracic pressure of 5 to 10 mm Hg (watch blood pressure).
· Hemodynamic support for off-pump coronary artery bypass (OPCAB) surgery may be necessary.

Figure 6.3 The flow chart indicates the procedural algorithm of the single- or two-stage hybrid coronary revascularization.
Figure 6.4 Anticoagulation and antiplatelet therapy strategy in single stage hybrid coronary revascularization.

Single-Lung Ventilation
·    Deliver approximately 10 mL/kg of tidal volume prior to and during single-lung ventilation. Tidal volume may need to be decreased because large tidal volumes can cause shifting of the mediastinum, which may cause the stabilizer to slip and effect the stabilization.
·    Keep the O2 saturation greater than 90%. If the saturation begins to decrease, the following should be carried out:
    Add continuous positive airway pressure (CPAP) of 5 cm H2O to the deflated lung. This can be performed through the bronchial blocker by inserting a 7 Frendotracheal tube (ETT) connector into the barrel of a 3-mL syringe. Insert the syringe tip into the lumen of the bronchial blocker. Attach the 7 ETT connector to a CPAP circuit.
    CPAP can be increased but if it is increased too much it will cause the lung to inflate and obscure the surgeon’s view.
Perfusion Considerations
·  The need for extracorporeal support is rare. A supported coronary revascularization would only require a system with a venous reservoir, arterial pump, oxygenator, and filter. It is recommended that the extracorporeal support system and devices be on standby. The use of a cell saver is recommended. Percutaneous cannulae are necessary if femoral cannulation is used for hemodynamic support.

4. Surgical Technique
Preparation, Positioning, and Draping
  Initial positioning of the patient can have a considerable effect on the operative procedure because proper positioning minimizes interference from internal and external body structures by the robotic equipment. Judicious care at this stage ensures the necessary landmarks for port placement to maximize intraoperative robotic arm maneuverability.
   The patient is positioned at the left edge of the operating room table. A comfortable support is placed under the distal two-thirds of the left side of the patient’s thorax. This usually takes the form of a rolled-up towel and should elevate the patient’s thorax by 6 to 8 inches superiorly. The left arm is positioned at the side of the operating room table to allow the left shoulder to drop posteriorly. Rotate the table 30 degrees up so the patient is in the partial left lateral position (Fig. 6.5). Leads and external defibrillator pads are positioned on the patient’s chest, away from the left lateral and midclavicular areas of the thorax, so as not to interfere with port placement. Place one pad on the right anterior lateral thorax and the other on the left posterior thorax. The patient is prepped in a routine manner for conventional CABG and saphenous vein harvesting, safeguarding against the possibility of having to convert the case to an open procedure. The only variation in preparation is exposure of the patient’s thorax and axilla on one side for port placement.
Figure 6.5 Proper patient positioning.
Direct Internal Thoracic Artery Harvest
Step 1. Patient Setup
·    Lines and airway double-lumen ETT with internal jugular central line.
·    Positioning is 30 degrees right lateral decubitus, with a roll under the left shoulder.

Step 2. Thoracotomy Incisions
·    Perform a 5- to 7-cm anterolateral minithoracotomy.
·    Male patients over the fifth or sixth intercostal space (ICS), one-third medial to the nipple.
·    Female patients inframammary incision in similar location.
·    Medial two-thirds of the window incision medial to the anterior axillary line.
·    Deflate left lung while making incision.
·   Divide intercostal muscles laterally to reduce risk of rib fracture, then divide them medially to avoid damage to LITA.
·    Soft tissue retractor may be placed in incision to maximize access.

Step 3. Direct Internal Thoracic Artery Harvest
·    Place a large Kelly clamp with a sponge in the sixth ICS to assist with harvesting the LIMA. Use the sponge to push away tissue for better internal thoracic artery (ITA) visualization.
·  Insert the ThoraTrak (Medtronic, Minneapolis) retractor system into the ICS incision; then hook the ThoraTrak retractor system to the Rultract Skyhook surgical retractor (Pemco, Cleveland) to facilitate the LITA harvest.
·  To prevent crush injury to the LIMA, make sure that the superior portion of the retractor is placed and maintained in the lateral aspect of the incision.
·   Care should be taken not to fracture a rib.
·  The ThoraTrak MICS retractor system should be opened slowly, which allows tissue and bone to acclimate to the change in position to minimize the potential for rib fracture and pain.
·    Start the LITA harvest at the third ICS using direct vision through the window incision.
·  Use an extended electrocautery instrument, endoscopic forceps, suction, endoscopic clip applier, and small clips for the harvest.
·    Complete the harvest up to the subclavian vein and down past the left fifth ICS.
·    Take care to identify and avoid the phrenic nerve.
·    During the LITA harvest, flexing the table may facilitate access to the superior portion of the LITA.
·    Anchor the pedicle of the LITA with silk ties to maintain the proper orientation.
·    Give intravenous bivalirudin or heparin prior to LITA division.

Endoscopic Robotic Harvesting of the Left Internal Thoracic
Artery and/or Right Internal Thoracic Artery
Step 1. Patient Setup
·    Positioning is 30 degrees right lateral decubitus, with a roll under the left chest to allow the shoulders to fall.

Port Placement and Intrathoracic Visualization
·    Proper port placement is fundamental to the success of the operation. Placement of each port is centered on constructing an ideal configuration that ensures mobilization of the ITAs from the first to the sixth ribs, with the least amount of impedance to the robotic arms. It is imperative that the surgeon be meticulous with each individual patient, taking the necessary time needed to ensure proper completion of port placement prior to surgery. Suboptimal port placement can frequently result in dangerous internal and/or external robotic arm collisions.
· The lack of intrathoracic visualization is the premiere challenge to determining port placement. Careful review of the coronary angiogram, chest radiographs, and computed tomography (CT) scans of the heart with contrast preoperatively, along with direct examination of the anatomic structures of the individual patient in the operating room, help alleviate this problem.

Chest Radiography
·    Evaluate the chest radiograph in an orderly manner. Identify pertinent thoracic landmarks— suprasternal notch; angle of Louis; xiphoid; second to fifth ICSs; LITA and right internal thoracic artery (RITA) locations, 1 to 3 cm lateral to the sternum.
·    Note the position of the heart in the mediastinum. Note the size of the heart in relation to the pleural space on the port access side of the chest. On the lateral view, observe the degree of space between the anterior surface of heart and underside of the thorax.

Computed Tomography of the Heart
·  Assess the intrathoracic space. The distance from the pleural surface to the mediastinum cannot be less than 1.7 cm at the camera port space, which is usually the fifth ICS (Fig. 6.6). A distance less than 1.7 cm will not provide adequate intrathoracic space for adequate degrees of freedom of the robotic instrument.
      Rule out any other anatomic abnormalities, such as asbestos plaques.
   Determine the anteroposterior (AP) measurement and transverse (Trv) distance of the chest cavity. If the AP/Trv ratio is less than 45%, it reduces the success of robotic-assisted coronary artery revascularization.26 In addition, the vertical distance from the LAD to the chest wall is also a factor in the success of the operation. If this distance is less than 15 mm, there is a lower chance of being able to perform the operation robotically27 (Fig. 6.7).
      Assess the location of the coronary arteries if intramyocardial. Access to intramyocardial vessels for revascularization is challenging and can result in conversion (Fig. 6.8).
Figure 6.6 Computed tomography showing the distance from the pleura to the mediastinum.
Figure 6.7 Anteroposterior (AP), transverse measurement (TVR), and left anterior descending (LAD) to chest wall distance.
Figure 6.8 Intramyocardial location of left anterior descending (LAD) coronary artery.

Direct xamination of the Patient Thorax
·    Evaluate the external anatomic characteristics of the patient’s thorax, and conceptualize the internal anatomic characteristics based on the previously viewed chest x-ray, CT scans, and preoperative coronary angiogram.
·    With a felt marker, outline precisely where each port is to enter the thoracic cavity, using the standardized guidelines discussed in the following (see Fig. 6.5). Make necessary adjustments for individual patients based on information acquired from diagnostic imaging and the patient examination.

Step 2. Endoscopic Port Insertion
·    The left lung is deflated, and the 12-mm port is inserted in the fifth ICS.
·    CO2 insufflation is provided to maintain an intrathoracic pressure of 5 to 10 mm Hg (watch blood pressure).
·   A 30-degree endoscope is inserted. Under guidance of the endoscope, two 7-mm ports are inserted in the third and seventh ICSs.
·    The LITA is harvested from the first to the sixth rib endoscopically or robotically.
·  Prior to ligation of the LITA, the patient is given intravenous bivalirudin or heparin depending on the stage of the procedure (1 or 2).
·    The LITA pedicle is transected. To avoid torsion, using a clip, it is attached to the edge of the pericardium in the normal anatomic orientation at the site where the anastomosis is to be performed.

Step 3. LITA-LAD Anastomosis (Applies to Direct and Robotic Harvest Techniques)
·    The LITA-LAD anastomosis is performed under direct vision through the minithoracotomy.
·    Only soft tissue retraction is generally required, minimizing trauma.

    Pericardial fat is first removed.
    The pericardium is opened down to the diaphragm and toward the right pleura, 2 to 3 cm anterior to the phrenic nerve.

·    The LAD artery is identified based on its location on the ventricular septum, going to the apex.
·    Insert the long needle under direct visualization of the endoscope to identify the optimal ICS to perform a thoracotomy for best exposure of the LAD.
·    Insufflation can be momentarily stopped to take away the shift in the mediastinum.
·    Mark the intercostal space from the inside using electrocautery.
·    If robotic assistance is used, the robot is undocked and instrument ports are removed.
·    A mini anterior thoracotomy is performed.
·    Identify the pericardiotomy site and ITA pedicle.
·    Detach the ITA, deliver through an incision, and immediately place two suspension sutures to prevent the pedicle from twisting.
·    Assess ITA length and flow and prepare for anastomosis.
·    Select the port site for the endoscopic Octopus Nuvo stabilizer (Medtronic, Minneapolis; Fig. 6.9) sixth ICS if the LITA is harvested directly or the fifth ICS port site if the LITA is robotically harvested.
·    Achieve stabilization.
·  Apply proximal and distal occlusion snares or an intravascular shunt, depending on the patient’s hemodynamics.
·    Perform anastomosis in the usual fashion.
·    Check graft flow using an intraoperative flow-measuring device.
·    Carry out intraoperative angiography to check ITA patency and PCI of other coronary vessels at the same time (if one-stage procedure) in the specialized hybrid operating room (Fig. 6.10).
Figure 6.9 Octopus Nuvo stabilizer.
Figure 6.10 Hybrid cardiac operating room at the London Health Sciences Centre and Canadian Surgical Technologies and Advance Robotics (CSTAR). The room is fully equipped for robotic surgery, angiography, and percutaneous coronary intervention.
Results, Institutional Experience, and Current Evidence
·    Since 2004, at the London Health Sciences Centre, a total of 153 consecutive patients (age, 61.4 ± 11.1 years; 118 males and 35 females) underwent HCR (robotic-assisted MIDCAB graft of the LIMA to the LAD and PCI in a non-LAD vessel), 120 of which were a single simultaneous procedure. Of the remainder undergoing staged procedures, 19 patients underwent PCI before surgery, and 14 patients underwent PCI at a separate setting after surgery. Successful HCR occurred in 146 of the 153 patients; 7 patients required intraoperative conversion to conventional coronary bypass. DESs were used in 139 patients, and 14 patients were treated with bare metal stents. In the series of patients who underwent successful HCR, no perioperative mortality occurred; there was only one perioperative MI (0.6%), two cerebral vascular accidents (1.3%), and one respiratory failure with prolonged ventilation (0.65%). The rate of reoperation for bleeding was 2.6% (n = 4). Only 13.0% of patients (n = 20) required a blood transfusion. None of the patients developed acute kidney injury (AKI) with a need for kidney replacement therapy. The average intensive care unit (ICU) stay was 1 ± 1 days and the average hospital stay was 4 ± 2 days. Coronary angiography follow-up at 6 months was performed in 95 patients. Angiographic evaluation demonstrated an LITA anastomotic patency of 97.9% and a PCI vessel patency of 92.6%. Clinical follow-up at 83.6 ± 11.1 months demonstrated 93.9% survival, 91.2% freedom from angina, and 88.5% freedom from any form of coronary revas- cularization. PCI to LITA to LAD anastomosis was performed in 5 patients; in one case, the anastomosis was surgically revised, and PCI was repeated to non-LAD vessels in 11 patients.
    We also performed a comparative analysis of HCR to conventional on-pump CABG with an adjusted analysis using inverse probability weighting (IPW) based on the propensity score of undergoing on-pump CABG or HCR from patients in our institution. We considered all double on-pump CABG (n = 682) and HCR (147 RADCAB grafts of the LITA to the LAD and PCI to one of non-LAD vessels) procedures between March 2004 and November 2015. We performed IPW-adjusted analysis of the outcomes using the teffects ipw package (for estimating treatment effects) using the average treatment effect (p < 0.05 was considered significant). In the two groups, there were no statistically significant difference in the rate of re-exploration for bleeding (CABG, 1.7%; HCR, 2.8%; p = 0.44), perioperative MI (CABG, 1.1%; HCR, 1.4%; p = 0.79), stroke (CABG, 2.4%; HCR, 2.1%; p = 0.83), need for hemodialysis (CABG, 0.4%; HCR, 0%; p = 0.16), prolonged mechanical ventilation (CABG, 2%; HCR, 0.7%; p = 0.15), ICU length of stay (CABG, 1.7 ± 2.3 days; HCR, 1.0 ± 0.8 days; p = 0.23). HCR was associated with a lower blood transfusion rate (CABG, 25%; HCR, 14%; p = 0.002), lower in-hospital mortality (CABG, 1.3%; HCR, 0%; p = 0.008), shorter hospital length of stay (CABG, 6.7 ± 4.7 days; HCR, 4.5 ± 2.1 days; p < 0.001). After the median follow-up period of 70 months (37–106 months; CABG group), and 96 months (53–114 months; HCR group) there was no significant difference in survival (CABG, 92%; HCR, 97%; p = 0.13) and freedom from any form of revascularization (CABG, 93%; HCR, 91%; p = 0.27). HCR was superior in freedom from angina (CABG, 70%; HCR, 91%; p < 0.001). Using the same methodology, we also performed a comparative analysis to off-pump CABG. Our sample consisted of all double off-pump CABG (n = 216) and HCR (147 RA-CABG grafts of the LITA to the LAD and PCI to one of non-LAD vessels) procedures performed between March 2004 and November 2015.
    We found that in the two groups, there were no statistically significant differences in the rate of re-exploration for bleeding (CABG, 1.5%; HCR, 3.5%; p = 0.36), postoperative atrial fibrillation (CABG, 19%; HCR, 12%; p = 0.13), perioperative MI (CABG, 0.5%; HCR, 1.4%; p = 0.36), stroke (CABG, 1.0%; HCR, 2.1%; p = 0.88), renal failure with need for hemodialysis (CABG, 0.5%; HCR, 0%; p = 0.31), blood transfusion (CABG, 28%; HCR, 15%; p = 0.60), in-hospital mortality (CABG, 1.0%; HCR, 0%; p = 0.15), ICU length of stay (CABG, 1.8 ± 1.3 days; HCR, 1.0 ± 0.8 days; p = 0.10). There was a higher rate of in-hospital re-intervention in the HCR group in order to revise the LITA-LAD graft after intraoperative angiography (CABG, 0%; HCR, 3.4%; p = 0.029). HCR resulted in a lower incidence of postoperative prolonged mechanical ventilation (CABG, 4%; HCR, 0.7%; p = 0.017). The hospital length of stay was significantly shorter in patients who underwent HCR (CABG, 8.1 ± 5.8 days; HCR, 4.5 ± 2.1 days; p < 0.001). After the median follow-up periods of 81 months (48–113 months; CABG group) and 96 months (53–115 months; HCR group) there was no significant difference in survival (CABG, 85%; HCR, 96%; p = 0.054) and freedom from any form of revascularization (CABG, 92%; HCR, 91%; p = 0.80). HCR was superior in terms of freedom from angina (CABG, 73%; HCR, 90%; p < 0.001).
·  Our experience and that of others has suggested that a hybrid revascularization strategy is safe and provides excellent short- and long-term results, with a low rate of postoperative complications, shorter hospital stay, fast recovery time, and very good rates of freedom from angina, freedom from any revascularization, and long-term survival. In recent years, there has been an increasing trend toward hybrid revascularization procedures due to a continuous improvement of DES performance and a broader use of minimally invasive techniques, especially with robotic assistance.
·   The major advantages of HCR when compared with conventional CABG are the avoidance of cardiopulmonary bypass, aortic clamping, and sternotomy while still providing the survival benefit of the LITA-LAD anastomosis. With the addition of PCI, complete revascularization of all significantly diseased arteries is ensured.
·  However, if the rationale behind this alternative form of coronary revascularization is well established, HCR has failed to be broadly adopted so far. The STS adult cardiac surgery database has shown that from July 2011 to March 2013, HCR represented only 0.48% of the total CABG volume (950 of the total of 198,622 patients who underwent CABG).30 The reasons why physicians and surgeons have not currently embraced this in routine clinical practice could be related to the fact that minimally invasive LITA-LAD anastomosis construction is technically demanding, and there are still costs and logistical problems associated with performing two procedures with different periprocedural management protocols. There is also a lack in validation from randomized clinical trials comparing HCR with conventional CABG. However, a few recent studies have highlighted the good preliminary results of this technique, including its advantages and disadvantages. Harskamp et al. reported the first meta-analysis of more than 1100 patients who underwent HCR from six observational cohort studies.31 They observed that patients undergoing HCR have a similar risk of the composite of death, MI, stroke, and repeat revascularization as those treated with CABG during hospitalization and follow-up (4.1% of patients after HCR and 9.1% of patients with CABG at 1-year follow-up). Death, MI, and stroke rates were numerically but not statistically lower with HCR. The need for repeated revascularization occurred more frequently with HCR (8.3% of patients after HCR and 3.4% of patients after CABG at 3-year follow-up; p < 0.001). These findings were similar when HCR was performed as a single- or dual-stage procedure.
·  The data generated by this meta-analysis also support the finding that HCR performed without conventional sternotomy results in a shorter duration of hospital stay, earlier return to work, and fewer in-hospital complications. It also showed that self-reported quality of life is significantly higher at follow-up. These data are in line with our findings. In our analysis, we observed a shorter length of stay in the ICU (1 ± 1 days) and average hospital stay of 5 ± 2 days. None of our patients developed renal failure with the need for dialysis, and only 13.2% of patients required a blood transfusion. We also observed a lower rate of repeat revascularization, with a very good long-term freedom from any revascularization (in 90.7% of patients at clinical follow-up of 77.8 ± 41.4 months). The results of new-generation DESs are playing an important role in coronary revascularization and could contribute to a wider diffusion of HCR. The use of newer DESs show favorable outcome,32-34 especially if compared with the results of first generation stents and venous grafts, which are more prone to atherosclerotic degeneration and progressive narrowing, with high early and long-term failure rates, as shown in the PREVENT IV study.8
·  In another meta-analysis, Zhu et al. analyzed data from 10 cohort studies involving 6176 patients.11 They calculated the summary odds ratio (OR) for primary endpoints (e.g., death, stroke, MI, target vessel revascularization, major adverse cardiac or cerebrovascular events) and secondary endpoints (e.g., atrial fibrillation, renal failure, length of stay in the ICU, length of stay in hospital, red blood cell transfusion). They found that HCR was noninferior to CABG in terms of major adverse cardiac or cerebrovascular events during hospitalization (OR, 0.68; confidence interval [CI], 0.34–1.33) and at 1-year follow-up (OR, 0.32; CI, 0.05–1.89). No significant difference was found between the HCR and CABG groups in regard to in-hospital and 1-year follow-up, outcomes of death, MI, stroke, atrial fibrillation, and renal failure. However, HCR was associated with a lower requirement for blood transfusions and shorter length of stay in the ICU and length of stay in hospital than CABG (weighted mean difference, −1.25; 95% CI, −11.62–10.88; −17.47, −31.01–3.93; −1.77, −3.07 to −0.46, respectively). Harskamp et al. compared HCR versus standard CABG using a propensity score matching algorithm.12 They studied 306 patients who underwent HCR and matched them in a 1 : 3 ratio to 918 patients who underwent standard CABG. They found that the 30-day composite of death, MI, or stroke after HCR and CABG was 3.3% and 3.1%, respectively (OR, 1.07; 95% CI, 0.52–2.21; p = 0.85). HCR was associated with lower rates of in-hospital major morbidity (8.5% vs. 15.5%; p = 0.005), lower blood transfusion use (21.6% vs. 46.6%, p < 0.001), lower volume of chest tube drainage (690 mL; 25th–75th percentile—485–1050 mL vs. 920 mL, 25th to 75th percentile; 710–1230 mL; p < 0.001), and shorter postoperative length of stay (<5-day stay—52.6% vs. 38.1%; p = 0.001). during the 3-year follow-up period. Mortality was similar after HCR and CABG (8.8% vs. 10.2%; hazard ratio = 0.91; 95% CI, 0.55–1.52; p = 0.72).
· Only one small randomized controlled trial comparing HCR with CABG has recently emerged in the medical literature.35 In this study, a total of 200 patients with multivessel CAD involving the LAD and a critical lesion in at least one major epicardial vessel amenable to PCI and CABG and referred for conventional surgical revascularization were randomly assigned to undergo HCR or CABG in a 1 : 1 ratio. The primary endpoint was the evaluation of the safety of HCR. The feasibility was defined by the percentage of patients with a complete HCR procedure and the percentage of patients with conversion to standard CABG. They also assessed the occurrence of major adverse cardiac events such as death, MI, stroke, repeated revascularization, and major bleeding within a 12-month follow-up period. Of the patients in the HCR group, 93.9% had complete HCR, and 6.1% patients were converted to standard CABG. At 12 months, the rates of death (2.0% vs. 2.9%, p = not significant [NS]), MI (6.1% vs. 3.9%; p = NS), major bleeding (2% vs. 2%; p = NS), and repeat revascularization (2% vs. 0%; p = NS) were similar in the two groups; no cerebrovascular accidents were observed.
· Patient selection is another crucial factor for HCR. We cannot emphasize enough the importance of the heart team in guiding appropriate patient selection for HCR. The ideal patient is a patient with multivessel CAD with a complex proximal LAD lesion suitable for LITA-LAD grafting, associated with significant but not overly complex non-LAD lesions suitable for PCI, with no contraindications for dual antiplatelet therapy. The high likelihood of achieving a complete revascularization with such an approach is certainly one of the most important guiding factors. Complex distal left main lesions may be suitable and ideal for HCR if the circumflex artery territory is amenable for PCI. As noted, the lack of large randomized controlled trials, however, does not allow the identification of an optimal HCR target group of patients.
·  Another important factor is the choice of proper timing for the two procedures. In other words, it should be determined if it is better to perform the one-stage treatment of CAD (simultaneous HCR) or in two separate settings (two-stage HCR). Most of our patients (71.9%) underwent single-stage HCR. The decision is guided by patient characteristics and available facilities, but we acknowledge that this approach has several advantages, including that it is more cost-effective, reduces the length of stay, increases patient satisfaction, and allows the immediate confirmation of the patency of the LITA graft. The main disadvantage is the risk of bleeding due to the use of dual antiplatelet therapy. For this approach, an equipped hybrid operating room is mandatory. The two-stage procedure is generally favored based on clinical presentation and anatomy. PCI as the initial procedure, followed by CABG, is usually encountered in the setting of acute coronary syndrome when the non-LAD culprit lesion is initially addressed in the catheterization laboratory.
·  Another disadvantage is the risk of bleeding due to the uninterrupted antiplatelet therapy when the patient undergoes the subsequent surgical LITA anastomosis. In the two-stage approach, we generally prefer performing LITA-LAD bypass grafting before PCI when clinically appropriate. The main advantages of this strategy are the immediate angiographic check of the LITA-LAD anastomosis at the same time as the PCI, protection of the anterior wall of the left ventricle, which lowers the risk of PCI and, theoretically, the decreased risk of bleeding, considering that full antiplatelet therapy is not initiated prior to surgery. One of the major perioperative concerns of HCR is management of antiplatelet therapy, with the related risk of bleeding or stent thrombosis. In our series, we observed only one subacute stent thrombosis; this occurred in our early experience, when heparin was overlapped with bivalirudin. One of the arguments against HCR has been that the LITA-LAD anastomosis is technically highly demanding, and this could interfere with its patency rates. We previously reported two studies with angiographic follow-up of patients who underwent HCR. In the first study of 58 patients undergoing HCR,36 at a mean follow-up of 20.2 months, the LITA-LAD anastomosis was patent in 49 of the 54 patients who had repeat catheterization (91%). Later, in 2014, we published a series of 94 patients who underwent HCR and had angiographic follow-up at 6 months illustrating a 94% anastomotic patency of the LITA-LAD.37 This compares favorably with the LITA patency seen with conventional surgery.

Keywords : coronary revascularization, hybrid, PCI, minimally invasive CABG robotic, Operations for Coronary Artery Disease

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