Approach shows promise of combining best of CABG and PCI, but evidence to date is not adequate
Hybrid coronary revascularization (HCR), which combines coronary artery bypass grafting (CABG) and percutaneous coronary intervention (PCI), might offer the durability and long-term mortality benefit of a left internal mammary artery (LIMA) graft while maintaining a low-risk of immediate complications that accompany PCI, according to a study published Monday.
Over the last decade, improvements in the prevention and treatment of cardiovascular disease have led to a 10% relative reduction in mortality, yet cardiovascular disease continues to be the leading cause of death globally. Nevertheless, a significant number of patients require revascularization to prolong life and lessen symptoms, which traditionally has been achieved with CABG or PCI. Neither strategy is without risk. PCI offers low upfront risk with less durability; conversely, CABG is accompanied by higher early risk with sustained durability.
Pedro R. Moreno, MD, of Mount Sinai Hospital, New York, and co-investigators offer a comprehensive summary of the available literature regarding HCR while emphasizing the need for randomized clinical trials comparing HCR to CABG or PCI alone. Their report was published in the July 21 issue of the Journal of the American College of Cardiology.
Revascularization using both CABG and PCI in the same patient is referred to as HCR and can, in theory, offer the advantages of each method while minimizing the associated risk. By omitting additional saphenous vein grafts (SVGs), surgeons can perform off-pump and sternal-sparing CABG by implanting a LIMA graft to the left anterior descending (LAD) artery, improving short-term outcomes while benefiting from the durability and proven mortality benefit of the LIMA. Numerous studies have demonstrated unacceptable SVG failure rates as high as 45% at 12 to 18 months compared to studies reporting contemporary drug-eluting stent (DES) patency rates of 96% to 98%. Thus, a hybrid approach to revascularization may take advantage of each form of revascularization while optimizing short- and long-term outcomes.
HCR offers ideal revascularization to several patient subsets, such as obese patients, using a minimally invasive sternal-sparing approach to avoid sternotomy complications; those with porcelain aortas to decrease rates of stroke; those with depressed ejection fractions to avoid on-pump systolic failure; and patients who lack vein conduits.
Timing of each component can occur in three varieties. The first is CABG followed by PCI in a hybrid suite, occurring in 20% of all HCRs in the United States. This method offers immediate angiographic assessment of the LIMA to LAD graft, a protected LAD during PCI and surgical backup, should the need arise during PCI. However, there remain concerns regarding hybrid suite cost and stent thrombosis versus minimizing bleeding.
The second approach is CABG first followed by PCI in the days or weeks that follow. This approach also offers an immediate evaluation of the LIMA-to-LAD graft, although peri-anastomotic edema can create the appearance of stenosis in the days to weeks that follow CABG, and operators should have a high threshold to treat distal anastomosis with PCI. This approach offers delayed dual antiplatelet therapy (DAPT), thus lowering mediastinal bleeding risk.
The final approach is PCI followed by CABG, also referred to as reverse HCR. This approach is best in patients presenting with non-LAD plaque rupture acute coronary syndromes. PCI is performed upfront to stabilize the patient, followed by 30 days of DAPT, and then CABG. A significant downside to this approach is that surgery induces platelet activity and inflammation, promoting stent thrombosis. For those at high-risk of stent thrombosis, early admission and bridging from oral to intravenous P2Y12 inhibitors may augment risk pre-operatively.
Moreno and colleagues note that, to date, there have not been any completed prospective randomized clinical trials comparing HCR to either CABG or PCI that have been adequately powered. For example, several small prospective randomized trials demonstrated numerical trends in support of the use of HCR versus traditional CABG, but none of the studies were adequately powered to prove statistical significance.
The impact of HCR on cost has been studied, demonstrating a margin of $8,771 (p<0.0001) in favor of HCR when compared to CABG by reducing blood transfusions, mechanical ventilation and, thus, length of stay.
The Hybrid Trial was a National Heart, Lung and Blood Institute-sponsored multi-centered randomized controlled trial of HCR versus PCI involving 70 sites in North America. The trial was designed to demonstrate superiority of HCR to PCI for a composite of all-cause death, myocardial infarction, stroke or unplanned repeat revascularization. Unfortunately, it proved difficult to recruit patients for this study. Only 200 patients were enrolled, and the trial was stopped prematurely because of slow enrollment. Follow-up is scheduled through 2 years for these 200 patients.
An important consideration of HCR is the development and maintenance of the hybrid coronary heart team. This requires shared recognition between the interventional cardiologist and cardiothoracic surgeon that medical therapy, percutaneous revascularization and surgical revascularization all play key roles in the treatment and management of patients. There should be active collaboration considering all strategies to individualize patient care. The institutional hybrid coronary heart team must have a collective experience with the ability to offer state-of-the-art care (off pump and sternal sparing CABG, contemporary physiologic guided PCI). There should be a universal dedication to clinicians’ ethical obligation to provide the best care possible to each patient, Moreno and colleagues conclude.
Moreno PR, Stone GW, Gonzalez-Lengua CA, et al. The Hybrid Coronary Approach for Optimal Revascularization: JACC Review Topic of the Week. J Am Coll Cardiol 2020;76:321-33. https://doi.org/10.1016/j.jacc.2020.04.078