CHICAGO—In older patients with multivessel coronary artery disease (CAD) who did not require emergency treatment, there was a long-term survival advantage among those who underwent CABG as compared with those who underwent PCI following the procedure, according to a large registry analysis presented March 27 at the 61st annual American College of Cardiology’s (ACC) scientific session.

“Questions persist concerning the comparative effectiveness of PCI and CABG,” wrote the authors in the New England Journal of Medicine, where the study was simultaneously published. Thus, the ACC Foundation (ACCF) and the Society of Thoracic Surgeons (STS) collaborated to compare the rates of long-term survival after PCI and CABG by linking the ACCF National Cardiovascular Data Registry’s CathPCI Registry and the STS Adult Cardiac Surgery Database to claims data from the Centers for Medicare & Medicaid Services for the long term. The analysis, of which the preliminary results were presented at STS.12, drew data from 644 sites.

Principal investigator William S. Weintraub, MD, of Christiana Care Health System in Newark, Del., assessed more than 185,000 Medicare patients undergoing heart revascularization from 2004 to 2008. Among patients 65 years of age or older who had two-vessel or three-vessel CAD without acute MI, 86,244 underwent CABG and 103,549 underwent PCI. The median follow-up period was 2.67 years.

At one year, the study authors reported no significant difference in adjusted mortality between the groups (6.24 percent in the CABG group as compared with 6.55 percent in the PCI group).

However, at four years there was a lower mortality with CABG than with PCI (16.41 percent versus 20.8 percent). This long-term survival advantage after CABG was consistent across multiple subgroups based on gender, age, race, diabetes, body mass index, prior MI history, number of blocked coronary vessels and other characteristics. For example, the insulin-dependent diabetes subgroup that received CABG had a 28 percent increased chance of survival after four years compared with the PCI group.

Importantly, Weintraub said that “all observational studies have possible treatment selection bias, which can be approached, but not fully resolved, by careful design, statistical analysis and sensitivity analysis.” An example of a drawback with this observational study is that the researchers could not assess which patients were ineligible for CABG, which Weintraub acknowledged “could impact interpretation.”

In discussing the implications of comparative-effectiveness research, Weintraub said that observational studies can provide real-world outcomes with greater generalizability than randomized trials. “Linking robust clinical databases with administrative databases capitalizes on the advantages of both, which allows for very large studies with power to examine subgroups,” he added. “For comparative effectiveness to reach its potential, randomized trials and observational studies will both have critical roles to play.”

Given the caveats of observational studies, Weintraub told Cardiovascular Business that the trial wouldn’t have a tremendous impact on decision making in clinical practice, but it may allow surgeons and interventional cardiologists to collaboratively rethink their options.

However, Miguel Quinones, MD, chair, department of cardiology and medical director at The Methodist DeBakey Heart & Vascular Center in Houston, noted that randomized controlled trials, in addition to observational studies, should be examined together to see whether clinical practices should be changed. Also, Weintraub added that patient preference plays a role in those choices as well.

While this present analysis focuses solely on mortality, Weintraub said that additional analyses on composite endpoints, angiographic results and economic considerations will follow.

The National Institutes of Health’s (NIH) National Heart, Lung and Blood Institute funded the study.