The Synergy of Specialties

Hybrid coronary revascularization optimizes the strengths, curtails weaknesses of PCI and CABG.

The relatively new technique of hybrid coronary revascularization aims to combine the durability of CABG with the non-invasiveness of PCI in patients with multivessel CAD.

Based on the results of HYBRID, the first randomized pivotal trial comparing hybrid coronary revascularization (HCR) with CABG, this combination procedure is well on its way toward achieving this goal. The study data, which were reported at the 25th annual Transcatheter Cardiovascular Therapeutics meeting in 2013, found that HCR was feasible and safe when compared with CABG.

In terms of feasibility, the study’s primary endpoint — the rate of conversion to surgery — was 6.1%. HCR also yielded an 89.8% rate of freedom from MACE at 12 months, which was not significantly different from the rate of 92.2% observed with CABG.

“We cannot make any firm conclusions on this basis, but our results strongly support the concept of HCR,” said Michal Hawranek, MD, PhD, interventional cardiologist at the Silesian Center for Heart Diseases in Zabrze, Poland, who worked on the HYBRID trial alongside study organizers Mariusz Gąsior, MD, PhD, and Marian Zembala, MD, PhD. “It seems to be safe and feasible in a select population of patients.”

In addition to its promise in merging the best of both worlds for patients, the field of HCR is also poised to bridge the gap between cardiac surgeons and interventionalists.

“More than any other treatment modality, HCR requires a functioning heart team to tailor optimal treatment based on detailed individual clinical, anatomic and functional considerations,” said Ivy S. Modrau, MD, junior consultant of the department of cardiothoracic and vascular surgery at Skejby Hospital, Aarhus University Hospital, Aarhus, Denmark. “Cardiac surgeons and interventional cardiologists realize that competitive treatment modalities can be complementary to the advantage of our patients.”

HCR: How and Why

HCR has been performed since the late 1990s, Modrau said, and is often employed in specific patient subsets to minimize surgical risk. She said HCR procedures generally consist of a minimally invasive left internal mammary artery (LIMA) to left anterior descending (LAD) graft, along with PCI of other lesions.

“The rationale for HCR is to combine the proven prognostic benefits of the LIMA-to-LAD graft with reduced invasiveness of PCI to minimize discomfort and reduce postoperative morbidity, especially the risk for stroke,” she said.

In many centers, Modrau said HCR is performed by minimally invasive direct coronary artery bypass (MIDCAB) through a minithoracotomy. She said thoracoscopic or robotic assistance may be used to harvest the LIMA graft.

“At our institution, we have chosen to perform the LIMA-to-LAD graft off-pump through an inferior reversed J-hemisternotomy — a procedure we have named JOPCAB,” Modrau said. “This procedure features technical ease and excellent exposure of the heart.”

According to John G. Byrne, MD, chief of the division of surgical cardiology at Brigham and Women’s Hospital, Boston, choosing the right candidate for HCR depends not only on the complexity of the disease as determined by the SYNTAX score, but also on the anatomy of the patient.

“An ideal hybrid patient would be someone who, for example, has a high-grade, non-stentable proximal LAD, but with a stentable true circumflex lesion with obtuse marginals that cannot be easily grafted,” he said. “So you treat the circumflex with a stent because that would be hard to graft, and you treat the LAD with a graft because it would be hard to stent. That’s probably the best of both worlds.”

Nikolaos E. Bonaros, MD, associate professor of cardiac surgery, Innsbruck Medical University, Innsbruck, Austria, said the two components of HCR can be performed in various different chronologies.

“The sequence of events can be different; you can perform both procedures simultaneously, or you can perform the minimally invasive CABG before the PCI, or the other way around,” he said. “It depends on the individual patient and their disease.”

Bonaros said although there are patients who qualify for simultaneous HCR surgery, his institution does not favor it.

“We have begun to move away from the simultaneous approach because it is too complex,” he said. “You have to combine antiplatelet therapy in the OR, and this can increase the risk for bleeding. For that reason, we don’t favor it.”

Modrau said a two-staged approach to HCR with surgery prior to PCI minimizes bleeding risk because antiplatelet therapy can be administered after the surgical procedure.

“In addition, the quality of the LIMA graft can be assessed angiographically,” she said. “The disadvantage is that a failed PCI may result in an incomplete revascularization.”

A third approach — two-stage HCR with PCI performed first — is frequently employed in patients who present with acute MI, Modrau said. This modality reduces perioperative ischemic burden, and also allows grafting of non-LAD vessels in the event of subpar PCI results.

“In this scenario, surgery has to be performed during dual antiplatelet therapy treatment, with the increased risk for bleeding complications,” she said. “In addition, the LIMA graft patency cannot be assessed routinely.”

Modrau said although simultaneous or “one-stop” HCR presents bleeding risk and also a risk for stent thrombosis due to a general postsurgical inflammatory response, it is undeniably convenient for patients.

“The biggest issue regarding simultaneous HCR might be logistics, and the need for a hybrid operating suite,” she said.

Advantages Over PCI and CABG

By offering the best of both worlds, HCR also seeks to avoid the worst of each of its respective components. In the case of CABG, HCR reduces invasiveness and its attendant complications.

“Sternotomy may be associated with pain, wound infection, pulmonary dysfunction, brachial plexus injury, bleeding, cosmesis, cardiopulmonary bypass-enhanced inflammatory response, cognitive deficits, coagulopathy or hemodilution,” Hawranek said. “When we use mini-invasive surgery, almost all of these disadvantages can be overcome.”

In offsetting the disadvantages of PCI, HCR improves long-term patency in patients for whom it is appropriate, Hawranek said.

“The main limitation of PCI is durability,” he said. “We feel safe performing PCI with new generations of DES within non-LAD territory. It is possible that HCR could be the most durable method of coronary revascularization for a selected population of patients.”

Nevertheless, Hawranek said HCR is not a viable choice for all patients, and is generally not preferable to PCI or CABG at this time.

“HCR is a very promising concept for treating CAD, but it has some limitations,” he said. “First, it should not be used in all patients with multivessel coronary disease; when there’s more than one chronic total occlusion besides the LAD, the results of PCI will probably not be satisfactory. So the atherosclerotic burden and lesion morphology will determine qualification for HCR.”

Ongoing Studies

In 2010, Modrau and colleagues began a pilot study of 100 patients with multivessel CAD (including an LAD lesion) undergoing planned, staged HCR. She said in most patients, her institution’s surgical approach — JOPCAB — was performed prior to PCI, while PCI was performed before surgery in a select number of patients with total occlusion of a non-LAD vessel.

“We were able to demonstrate that planned HCR is feasible, as the procedure was carried out according to the preoperative strategy and without perioperative MACCE in 96% of the cases,” she said. “At 1 month, we observed no deaths, one stroke and two procedure-related MIs.”

Modrau said five patients underwent reoperation for graft dysfunction, and four of these were identified via angiography without prior signs of ischemia.

“The benefit of routine angiographic LIMA graft control was made abundantly clear,” she said.

Six patients required reoperation due to bleeding, and nine patients required red blood cell transfusion.

The study cohort has since undergone 1-year clinical and angiographic follow-up, with these results soon to be published. Modrau said a second part of the registry is currently recruiting patients. This part of the study will focus on assessing simultaneous HCR in 50 patients with multivessel CAD, including an LAD lesion.

“We will assess early feasibility and safety after 1 year, and evaluate clinically after 3 and 5 years,” she said. “In addition, we will register quality of life, pain and the total costs following intervention and compare the results with those of a group of age-, sex- and EuroSCORE-matched conventional CABG patients after 1 year.”

A Costly Proposition

One possible obstacle to more widespread use of HCR is the cost involved in combining these two procedures. Although it assimilates the best of each of its components, HCR also takes on some of the expenses of both.

“The matter of cost is definitely a factor,” Bonaros said. “For the grafting, you use material from the patient’s own body, so that doesn’t cost anything. But for a hybrid procedure, you also have to consider the cost of the stent.”

Bonaros said it is also essential to consider the cost of the patient’s care from beginning to end.

“We have to consider the expenses from the beginning of treatment until the patient goes back to work,” he said. “We have to factor in the length of stay in the hospital, the possible need for secondary hospitalization and time spent in the rehabilitation center.”

Hawranek agreed that although the cost of a procedure that enlists the skills of two specializations is, of necessity, more expensive than either of them alone, some long-term costs can be reduced by HCR.

“Of note is the fact that after HCR, patients recover much faster, and the time to return to work is shorter than after conventional CABG. In addition, a more durable revascularization can lower the incidence of additional revascularization procedures in the future among HCR-treated patients,” Hawranek said.

Byrne noted that the expense of HCR also depends on whether it is done as a staged procedure or as one-stop simultaneous surgery.

“If you go to the cath lab on Monday and into surgery on Wednesday, you’re looking at a prolonged length of stay,” he said. “You’re also dealing with two procedural suites and two sets of operators. You can see how that would be a very costly proposition. Whereas if you have one stop in a hybrid lab, you’re able to do everything under one roof, in one setting, at one time. So that’s probably more cost-effective.”

Modrau said avoiding excessive postoperative costs may also hinge on careful patient selection for HCR.

“The postoperative costs will depend highly on which patients are selected for HCR,” she said. “Patients with complex non-LAD lesions treated with PCI will prompt a high reintervention rate following HCR, with increasing costs.”

Bonaros said another way of evaluating the cost effectiveness of HCR is through quality-adjusted life years (QALY).

“We can measure the quality of life after an intervention — surgical or percutaneous — and then determine the amount of money an intervention costs to gain QALY,” he said. “We have saved about $6,000 per patient using hybrid revascularization compared with conventional CABG. Added to that, patients have a less likelihood of rehospitalization, and get to go back to work and their life quicker.”

Modrau said the expense of HCR will also inevitably vary between countries, since health insurance coverage may treat the procedure differently.

“The costs for HCR procedures will differ between countries due to differences in the specific reimbursement systems and postoperative management,” she said.

Hawranek said as part of the ongoing HYBRID trial, he and colleagues intend to study the issue of expense in HCR.

“In our HYBRID trial, we will perform a cost-effectiveness analysis, which may help put the HCR procedure in the national health care payer system,” he said. “If there is no reimbursement for specific hybrid revascularization procedures, no one could afford it in a routine manner.”

A True Heart Team

The integration of the best of PCI and CABG may ultimately have the unexpected effect of merging the best of cardiac surgery and interventional cardiology. And although the field is undoubtedly evolving in that direction, clinicians may not be altogether ready for this collaborative ideal.

“The major barrier to HCR is the way our traditional training paradigms are organized and executed,” Byrne said. “You have people who train in medicine and interventional cardiology, and have very little exposure to surgery, so they see the world through the lens of an interventional cardiologist. Then you have surgeons trained in general surgery and heart surgery who see the world through the lens of a surgeon. What we need now are hybrid training programs, hybrid departments and hybrid medical centers.”

Byrne said although viewing patients in terms of one’s own medical role is perfectly reasonable, this sort of thinking can be problematic in terms of recognizing cases where HCR would be ideal.

“When you send a patient to a surgeon, they’re going to think like a surgeon, and so of course they’re not going to necessarily think hybrid,” he said. “And when you send a patient to an interventionalist, they’re going to see the case through the lens of an interventionalist, and of course they’re not necessarily going to think hybrid, either.”

He said this, in a nutshell, is the major obstacle to HCR.

“That is the essence of the barrier to these ideas,” Byrne said. “It’s not the technology, which has been here for many years. It’s not the procedural suite. It’s the way we work together and look at the world.”

The fault, he emphasized, does not lie with the clinicians, who are doing their respective jobs to the best of their abilities.

“They are doing what they truly believe is right and proper and in the best interest of the patient,” he said. “But they are limited in their perspectives.”

In order to keep up with the advancing world of hybrid surgery, Byrne said, this single-minded approach to cardiac care will need to be relinquished in favor of teamwork.

“We need to rethink the cardiac delivery system,” said Byrne, who wrote an editorial on this subject published by the American College of Cardiology. “Rather than training people as ‘surgeons’ or ‘interventionalists,’ we should be training them as cardiac specialists.”

He said this type of change is likely to be slow and may be difficult to implement at some medical institutions.

“It has to be small, maybe pilot projects that pop up in very collaborative cultures,” he said. “We can also work within the traditional structures, such as the boards of our specialties, to change things. But that’s going to be difficult.”

In some cases, just observing the impact of a promising new modality can foster collaboration. Modrau said that at her institution, the “buzz” created by the success of HCR has brought about unprecedented teamwork.

“I’d like to emphasize the exciting spin-off that the implementation of HCR has had at our institution,” she said. “The number of coronary surgical procedures has increased substantially. Today, JOPCAB procedures constitute approximately one-quarter of all coronary surgery. A larger proportion of patients with stenosis of the proximal LAD alone — previously treated with PCI — are now revascularized with a LIMA graft. HCR has facilitated collaboration and mutual understanding within the heart team, to the advantage of our patients.” — by Jennifer Byrne

Disclosure: Bonaros, Byrne, Hawranek and Modrau report no relevant financial disclosures. Byrne and the author of this article are not related.