ASCERT Observational Study Finds Long Term Advantage for CABG Over PCI in High Risk Cases

A very large observational study finds that long-term mortality in high risk patients is lower after bypass surgery than after PCI. The results, which were previously revealed in January at the annual meeting of the Society of Thoracic Surgeons (STS), were presented in final form at the American College of Cardiology by William Weintraub and published simultaneously in the New England Journal of Medicine.

ASCERT (ACCF-STS Database Collaboration on the Comparative Effectiveness of Revascularization Strategies) is an NHLBI-funded study based on linked data from the STS, the ACC, and CMS administrative data. The study population included patients 65 or older with 2 or 3 vessel disease who underwent CABG or PCI in the period from 2004 through 2007. 189,793 patients were followed in the study; 103,549 received PCI and 86,244 underwent CABG. Median followup was 2.67 years.

1 year adjusted mortality:

  • 6.2% for CABG versus 6.55% for PCI (RR 0.95, CI 0.90-1.00)

4 year adjusted mortality:

  • 16.4% versus 20.8% (RR 0.79, CI 0.76-0.82)

The findings, the authors said, were consistent with data from both previous observational and randomized trials. But, they acknowledged, “the potential remains for unmeasured confounders to have influenced the findings.”

In an accompanying editorial, Laura Mauri writes that “it is plausible that, in patients with diffuse atherosclerosis, CABG reduces the risk of fatal myocardial infarction more effectively than does focal treatment.” But she expressed skepticism that CABG could be shown to be better in two-vessel disease or in patients with three-vessel disease with focal lesions. ASCERT also does not reflect either the recent advances in PCI technology or the “modern PCI strategies” which reserve PCI for ischemic lesions, she writes.

Observational studies can provide valuable information “but there is no substitution for randomized trials to eliminate selection bias between treatments.” Mauri concludes: “we must … continue to give priority to randomized trials on the most salient questions regarding treatment strategy.”

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