Testing for Myocardial Viability in Patients with Ischemic Heart Failure

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In a 10-year follow-up, myocardial viability does not predict benefit from revascularization or mortality.

We cardiologists have long lived with the idea that the assessment of myocardial viability should inform decisions about revascularization, particularly in patients with ischemic cardiomyopathy, but some studies have questioned this reasonable assumption. In a substudy of the STICH trial (which compared medical therapy alone with coronary artery bypass grafting [CABG] in patients with coronary artery disease and left ventricular ejection fraction [LVEF] of ≤35%; NCT00023595), the presence of myocardial viability was not associated with a survival benefit from CABG at a median follow-up of 5.1 years (NEJM JW Cardiol May 2011 and N Engl J Med 2011; 364:1462). The investigators have now analyzed associations of myocardial viability with LV function and outcomes at a median follow-up of 10.4 years.

Of the 1212 patients enrolled in STICH, 601 had myocardial viability testing, of whom 19% were classified as having no viability. The incidence of death at 10 years did not differ significantly between patients with or without myocardial viability. CABG was not more effective for patients with viability than those without viability.

LVEF was measured in 318 participants at baseline and 4 months. Patients with myocardial viability had a significant increase in LVEF at 4 months, whereas those without viability did not. Mortality did not correlate with LVEF change.

COMMENT

This study adds to the investigators’ prior contributions. In this population, myocardial viability did not dictate the likelihood of benefit from surgical revascularization. Also, change in LVEF, a surrogate outcome, failed to correspond with benefit.

I have some concerns about testing for interactions in relatively small groups. We need larger studies to be certain about these findings. Nevertheless, until people can demonstrate the value of testing for myocardial viability in patients with ischemic cardiomyopathy, we should hold off using these tests for similar patients to inform decisions.

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