Complete Revascularization Irrelevant for Most Multivessel Disease

Download this article's Factoid (PDF & PPT for Gold Subscribers)

Angiographic complete revascularization, whether percutaneous or surgical, does not improve 5-year outcomes in patients with multivessel disease. Even so, patients with the highest degree of incomplete revascularization showed a tendency toward poorer prognosis, according to findings published online May 16, 2011, ahead of print in Circulation.

For the single-center, observational study, Seung-Jung Park, MD, PhD, and colleagues at Asan Medical Center (Seoul, South Korea), enrolled 1,914 consecutive patients with multivessel disease who were treated with either DES implantation (73.1%) or CABG (26.9%) at physician discretion. Those with prior CABG, needing concomitant valvular or aortic surgery, or who presented with cardiogenic shock or recent AMI were excluded.

Complete revascularization was defined as any attempt to revascularize all diseased segments during the index hospitalization or within 30 days after the index procedure but before a new MI or urgent TLR. Angiographic complete revascularization, which was based on SYNTAX criteria, applied to all diseased coronary segments at least 1.5 mm in diameter.

Overall, angiographic complete revascularization was obtained in 917 patients (47.9%), including 40.9% of those who underwent PCI and 66.9% of those who underwent CABG. Completely revascularized subjects tended to be younger and have more extensive coronary disease than those with incomplete treatment.

Outcomes were adjusted with an inverse probability weighting method. At 5 years, patients had comparable rates of death, MACE (all-cause death, MI, and stroke), and MACCE (all-cause death, MI, stroke, and repeat revascularization) regardless of whether their revascularization was complete (table 1).

Table 1. Five-Year Outcomes

Calculations based on broader definitions of complete revascularization, including for large segments, those at least 2.5 mm in diameter, and proximal arteries, showed similar results. However, the degree of revascularization appeared to matter. Patients with incomplete revascularization in 2 or more vessels showed a “borderline significant association” for higher MACCE risk than their completely revascularized counterparts (adjusted HR 1.27; 95% CI 0.97-1.66; P = 0.079).

Putting the Results in Context

Complete revascularization has been regarded as key to better outcomes, with previous studies on PCI supporting that link, Dr. Park and colleagues note, adding that their findings are in agreement with recent research on CABG. “Because of technical complexity, low ejection fraction, or safety concerns regarding the implantation of multiple [DES], however, diseased segments have often been incompletely revascularized in patients undergoing PCI,” they write. “Furthermore, even with CABG, the strategy of [incomplete revascularization] has occasionally been adopted to reduce operation-related complications, particularly when minimally invasive or off-pump surgery is attempted.”

The investigators suggest several possible explanations for why their study showed no benefit from complete revascularization, even in PCI patients: the use of detailed angiographic analyses from a core laboratory, a higher than typical rate of complete revascularization, or inherent limitations to angiography.

Speaking in a telephone interview, Edward L. Hannan, PhD, of the University at Albany (Albany, NY), whose own research has documented the prevalence and effects of incomplete revascularization in New York State, said it was unusual to lump both treatments together. “To me, PCI is the more interesting one to be looking at,” he said.

PCI is more likely to result in incomplete revascularization, Dr. Hannan noted, adding that he was surprised the researchers actually found as high a prevalence as they did in the CABG group. “Usually with CABG, once you’re in there you’re going to do everything,” he explained. “With PCI, there’s [always the thought] that we could come back later and it’s no big deal.”

In an e-mail communication, Dr. Park clarified how physicians chose particular treatment strategies during the trial. Factors involved in the decision-making process included patient presentation and comorbidities, LVEF, objective ischemia evidenced by stress test, jeopardized myocardium of diseased segment, presence of viable myocardium, and anatomical complexity.

“When patients had a high surgical risk due to combined morbidity, PCI was preferred,” he said. “However, when patients had severe angiographic complexity or low left ventricular function, CABG was considered to be the primary option for multivessel disease.”

Study Caveats

In a telephone interview with TCTMD, Jeffrey W. Moses, MD, of Weill Cornell Medical College (New York, NY), seemed perplexed by the study’s methodology.

“My problem with this particular study, and maybe I didn’t read it closely enough, is I don’t know what the criteria was for calling something stenosed. It just says diseased,” he pointed out. “Diseased is too vague, and it’s intentionally vague. I have a real problem with that. Why isn’t there a specific quantitative threshold that they put in to decide that a segment was stenosed?” Furthermore, he added, the definition just specifies that operators attempted revascularization, not whether the attempt was successful.

Another issue, said Dr. Moses, is that the complete and incomplete revascularization groups represent 2 different populations, with the incompletely treated patients being far more likely to have 3-vessel rather than 2-vessel disease. “With all due respect to all the statistical adjustments, when you’re dealing with those kinds of conundrums, it’s hard for me to draw any conclusions from this article at all,” he stressed, commenting that the study also fails to address patient functional status and quality of life.

In terms of clinical practice, Dr. Moses noted, “Most people believe that leaving large ischemic territories behind is a bad idea. But this doesn’t address that. It’s not in the realm of physiology that we’re talking about, ie, how much ischemia is left behind.”

According to Dr. Park, if in fact major clinical outcomes are not improved by complete revascularization, the strategy may even be harmful.

“Predictably, the complex procedures [needed to achieve angiographic complete revascularization] increased the time of procedure or operation and use of medical devices and adjunctive medications. Accordingly, there may be a higher chance of periprocedural complications and long-term adverse events,” he explained. “This may offset the potential benefit of [complete revascularization], which may be complete flow restoration in all ischemic myocardium.”

Choosing the Right Test

Using angiography as the litmus test to determine “completeness” may explain the lack of difference, comments Harold L. Dauerman, MD, of the University of Vermont College of Medicine (Burlington, VT), in an editorial accompanying the paper. He suggests that, rather than using anatomy to guide treatment, fractional flow reserve (FFR) should be the “gold standard for choosing the right vessels to leave anatomically incomplete.”

Moreover, the study supports the idea that a strategy of “reasonable incomplete revascularization” is acceptable for both PCI and CABG, he adds. “On the other hand, extensive incomplete revascularization is likely to be hazardous and associated with significant residual angina burden, myocardium at risk, and adverse cardiovascular events; each patient’s place on the ischemic spectrum of risk needs to be identified before embarking on a revascularization strategy. The administration of optimal medical therapy (including dual antiplatelet therapy) may be critical to the choice and efficacy of different revascularization strategies.”

Dr. Hannan agreed with the message that incomplete revascularization is generally, but not always, undesirable.

“The best way to go is to figure out when incomplete revascularization is dangerous and when it isn’t. Certainly, the use of fractional flow reserve and IVUS make a lot of sense in terms of determining whether it’s beneficial to revascularize the other vessels,” he said, noting that his research group recently began collecting data on the real-world use of these technologies. “The only qualification I would put on that is that those things do cost money, and we’re now in an age when we worry about how we spend our money on health care.”

However, Dr. Hannan mentioned that FFR and IVUS guidance could have unpredictable effects. “You’ve done 1 vessel, and now the question is if you’re going to do another. So if you use IVUS or fractional flow reserve to make that determination, [the result] depends on your initial orientation. Are you using them to eliminate what you would have done otherwise? Or are you using them to do what you would not have done otherwise? You can use them to rule in or to rule out,” he commented.

 

---

Sources:
1. Kim Y-H, Park D-W, Lee J-Y, et al. Impact of angiographic complete revascularization after drug-eluting stent implantation or coronary artery bypass graft surgery for multivessel coronary artery disease. Circulation. 2011;Epub ahead of print.

2. Dauerman HL. Reasonable incomplete revascularization. Circulation. 2011;Epub ahead of print.

 

Related Stories:

•  Incomplete PCI Common, Problematic in Multivessel Disease
• Complete Revascularization May Improve PCI Outcomes in Multivessel Disease