Complete Revascularization Reduces Mortality, MI, and Repeat Procedures in Multivessel CAD: Meta-Analysis

A strategy of complete revascularization, either with PCI or bypass surgery, in patients with multivessel coronary artery disease significantly reduces all-cause mortality when compared with incomplete revascularization, according to the results of a new meta-analysis. In addition, complete revascularization is associated with significant reductions in MI and the need for repeat coronary revascularization.

Publishing their results in Catheterization and Cardiovascular Interventions, researchers including lead author Marco Zimarino, MD, of Gabriele d’Annunzio University (Chieti, Italy), say their results “extend previous knowledge, by documenting that the benefit of complete revascularization is obtained with current state-of-the-art revascularization techniques and likely optimal medical therapy.”

They add the benefit of complete revascularization appears to be larger in higher-risk patients and those with diabetes.

Michael Levy, MD, MPH, of Lahey Hospital and Medical Center (Burlington, MA), who wrote an accompanying editorial with his colleague Vigyan Bang, MD, told TCTMD that there are “number of moving parts” when it comes to examining data related to complete vs incomplete coronary revascularization. The vast majority of studies included in the meta-analyses were nonrandomized observational reports. The lone randomized trial included is a 219-patient European study that compared complete vs culprit lesion PCI in patients with multivessel disease and this trial was published more than decade ago.

Observational studies, noted Levy, are difficult to interpret, with physicians typically opting for complete revascularization in patients with easier-to-treat coronary lesions. Patients with highly calcified vessels, for example, those that would be unlikely to undergo complete coronary revascularization, might also have comorbidities that contribute to their condition.

“Naturally you’re selecting a patient with a terrible vessel to the incomplete group, but maybe they have a terrible vessel because they have severe, uncontrolled diabetes and renal failure, all of these issues that create the appearance of these types of lesions,” said Levy. Although the only way to truly get an answer to the question of complete vs incomplete revascularization would be to perform a randomized clinical trial testing the 2 approaches, Levy and Bang say the new report does suggest that, until proven otherwise, complete revascularization should be the goal when possible.

Reductions in Mortality, MI, and Repeat Revascularization

The meta-analysis included 28 studies and 83,695 patients with multivessel coronary disease followed for an average of 4.7 years. Importantly, the researchers excluded patients with STEMI.

Of the included patients, there was roughly an equal split between complete (48.5%) and incomplete (51.5%) coronary revascularization. PCI was the dominant treatment strategy, with 72.6% of patients receiving either a bare-metal or drug-eluting stent, while CABG surgery made up the rest of the procedures. Among the different studies—in addition to the 1 randomized trial, 5 were observational studies nested within a randomized controlled trial—the definition of complete revascularization varied, but the researchers defined complete myocardial revascularization as the treatment of coronary segments of at least 50% diameter stenosis.

Regarding the results, complete revascularization was associated with a 27% reduction in all-cause mortality compared with the incomplete approach. In an analysis looking at the heterogeneity among the studies, the risk of all-cause mortality was reduced 24% in the CABG subgroup and 27% in the PCI subgroup. Overall, MI was reduced 26% and the need for repeat revascularization procedures by 23% with the complete treatment strategy.

In a subgroup analysis, there was a significant reduction in MI and the need for repeat procedures with complete revascularization among patients treated with PCI but only a trend toward reduction in both endpoints among patients undergoing CABG.

Various Nuances to Strategies Exist

To TCTMD, Levy noted that when physicians encounter a patient with multivessel disease, it is not unlikely they would also have diabetes. In that type of patient, surgery is the recommended revascularization strategy based on data from the FREEDOM trial showing a reduction in mortality, MI, and stroke with CABG over PCI.

Overall, Levy said the clinical trials to date “tell us a piece of the story but don’t really get directly at the question” of whether or not there are advantages with complete revascularization over an incomplete approach. Given the 2 approaches, as well as the different revascularization options, a clinical would need to randomize patients to medical therapy, complete and incomplete revascularization with CABG, and complete and incomplete revascularization with PCI.

However, as he notes in the editorial, the revascularization strategy might even consider a third approach—that being a hybrid strategy where PCI and CABG surgery could be combined to treat patients with multivessel disease. Data to date are few and far between, but 1 meta-analysis recently showed that combining the 2 procedures—left internal mammary artery to the left anterior descending artery plus stents for the other vessels—might be effective, particularly in reducing the need for transfusions and speeding up recovery time.

The clinical guidelines have only recently begun to address the completeness of revascularization, with the 2014 European recommendations stating that the revascularization strategy in patients with multivessel disease should be determined by the “heart team.”

Sources: 
1. Zimarino M, Ricci F, Romanello M, et al. Complete myocardial revascularization confers a larger clinical benefit when performed with state-of-the-art techniques in high-risk patients with multivessel coronary artery disease: a meta-analysis of randomized and observational studies. Catheter Cardiovasc Interv. 2016;87:3-12.
2. Bang VV, Levy MS. In multivessel coronary artery disease, a “state of the art” randomized clinical trial of revascularization is needed [editorial]. Catheter Cardiovasc Interv. 2016;87:13-14.

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