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Hybrid coronary revascularization promising for certain patients

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ANAHEIM, Calif. — Hybrid coronary revascularization may be a good alternative treatment strategy for certain patients with multivessel CAD, according to a speaker at the American Heart Association Scientific Sessions.

“We have seen almost a dozen randomized trials over the last decade that have consistently been in favor of CABG over PCI for patients with severe multivessel coronary disease,” Michael E. Halkos, MD, MSc, associate professor of surgery and chief of the division of cardiothoracic surgery at the Emory University School of Medicine, said during a presentation. “The majority of that survival benefit with CABG is derived from the left internal mammary artery (LIMA) to the left anterior descending artery (LAD).”

Currently, there is a perception that there is a marginal benefit with saphenous vein grafts over drug-eluting stents for low-complex non-LAD lesions which includes patients with low to intermediate SYNTAX scores, Halkos said. Even for non-LAD territories, the argument is that DES provide comparable treatment to vein grafts in those vessels.

Additionally, multivessel PCI is commonly being performed because patients prefer to avoid major invasive surgery, according to Halkos. Many patients are also concerned about the higher immediate periprocedural morbidity rate with CABG compared with PCI.

“They’re not looking at 10- or 15-year survival; they’re looking at 30 days,” he said.

Despite concerns regarding CABG, it remains the best option for certain patients, according to Halkos, who said the survival benefit of CABG is directly proportional to anatomic complexity, which means that it is an effective strategy for patients with more severe and complex disease, higher SYNTAX scores, diabetes and left ventricular dysfunction.

“We know that LIMA is the best treatment for proximal LAD disease, that long-term patency of vein grafts is suboptimal and that patients and cardiologists are interested in the least invasive treatment option for patients,” he said.

Potential of hybrid revascularization

Hybrid coronary revascularization, Halkos said, may offer a solution to some of these problems faced by surgeons and cardiologists.

In terms of data, the findings regarding CABG vs. PCI can be misleading, according to Halkos, because vein graft failure is different from stent failure. Trials from the early 2000s show that vein graft failure at 1 year ranges from 5% to 30%, while stent failure appears to be much lower. However, he said, stent failure presents differently than vein graft failure. Whereas vein graft failure can be clinically silent, stent thrombosis or restenosis is frequently associated with at least minor clinical adverse events and frequently major adverse events.

Strokes after CABG are another area of concern, according to Halkos. Patients undergoing CABG often have many risk factors for stroke, including postoperative atrial fibrillation and atherosclerosis in the cerebrovasculature. Nevertheless, a significant percentage of patients undergoing CABG have postoperative strokes related to aortic manipulation, either from the heart-lung machine or clamping or manipulation of the aorta during the procedure. Studies have shown, for example, that patients in which there was no aortic manipulation during CABG had a stroke rate of about 0.6%, which is comparable to what is seen with cardiac catheterization, Halkos said.

Hybrid revascularization can offer a more attractive option by capitalizing on the main advantage of CABG, the LIMA to the LAD, while simultaneously lowering stroke risk, preventing sternal infections, reducing blood transfusions and allowing for a quicker recovery associated with less invasive surgery, according to Halkos.

It is important, though, that a delicate balance is struck between CABG and PCI, Halkos said. On one hand, PCI has lower procedural morbidity and may be comparable to CABG for low-complexity disease and certain left main CAD subgroups. Moreover, with the latest-generation DES, restenosis rates have improved. On the other hand, CABG is associated with higher procedural morbidity but is still the most durable option, has the least risk for repeat revascularization and is the most favorable for long-term symptom relief. It is also better than PCI for diffuse disease, high-complexity disease and three-vessel disease.

The goal, he said, should be to lower procedural morbidity with minimally invasive approaches so that CABG is comparable to PCI but that the long-term durability associated with LIMA-LAD grafting is still provided.

“We want the LAD to be treated with the LIMA, and the non-LAD vessels to be treated with PCI,” Halkos said. “We don’t want six or seven stents going in non-LAD vessels just for the sake of avoiding three- to four-vessel CABG, as was done in the PCI arm for SYNTAX. There is a delicate balance of where hybrid revascularization can fit, especially given what we have in terms of good, randomized trial data comparing PCI with CABG in favor of CABG. We have to be aware that an approach like hybrid revascularization could tilt that balance if it is not carefully and rigorously applied.”

Hybrid revascularization strategies, outcomes

The goal of hybrid revascularization, Halkos said, is not to affect the number of patients who require sternotomy multivessel CABG but rather to reduce the number of patients who should be getting a LIMA-LAD graft but are instead getting treated with PCI.

“This is the critical step,” Halkos said. “For hybrid revascularization to be an option, CABG has to be done in a less invasive, sternal-sparing manner.”

There are various strategies for minimally invasive CABG that have been validated at highly expert centers and can be tailored to an individual surgeon’s approach, according to Halkos. One example is a robotic-assisted approach in which the robot is used to harvest LIMA, open the pericardium and identify the target vessel. The surgeon then makes a small incision without spreading the ribs and performs LIMA-LAD CABG off pump.

Despite the validity of these strategies, studies evaluating the outcomes of hybrid revascularization are limited by their observational design, according to Halkos, with one of the most important limitations being that surgeons and interventional cardiologists carefully selected the patients in whom they performed hybrid revascularization.

Nevertheless, the outcomes have been fairly positive, with studies showing less bleeding, fewer surgical site infections, shorter ventilation time and less time spent in the ICU with hybrid revascularization, Halkos said. One study also found that hybrid revascularization was associated with a lower MACCE rate vs. CABG alone or PCI alone, particularly among sicker patients.

Halkos also cited a multicenter, NIH-sponsored, observational, prospective trial that showed some equipoise between multivessel PCI vs. hybrid multivessel revascularization in terms of MACE at 1 year, but the trial was not powered to detect a difference. “We are now participating in a large multicenter randomized controlled trial comparing PCI vs. hybrid revascularization for patients with multivessel CAD. This trial will provide valuable data about what is the best treatment strategy for patients that have anatomy that is amenable to PCI.

“Hybrid coronary revascularization is a safe and effective treatment for carefully selected patients with multivessel CAD. It requires a collaborative approach among cardiologists and surgeons,” Halkos said. “However, the ideal patient to be treated with the hybrid coronary revascularization approach is not well defined and institutional bias is important.”

Further study of the hybrid approach is necessary, according to Halkos. Fortunately, a randomized trial comparing the hybrid approach with PCI in patients with multivessel disease is currently enrolling, he said. – by Melissa Foster

Reference:

Halkos M. SA.CVS.2269. Controversies in Coronary Revascularization. Presented at: American Heart Association Scientific Sessions; Nov. 11-15, 2017; Anaheim, Calif.

Disclosure: Halkos reports he is a consultant and advisory board member for Medtronic.