Does Inducing Myocardial Ischemia During Stress Testing Help Identify Best Patients for CABG?

When it comes to identifying patients with coronary artery disease (CAD) with severe LV dysfunction who would benefit from CABG over optimal medical therapy, inducible myocardial ischemia during stress testing does not help, according to a study recently published in the Journal of the American College of Cardiology. External Link

The study assessed the outcomes of 399 patients from the STICH Trial, of which 197 were randomized to CABG and 202 were randomized to medical therapy. According to the study investigators, patients with and without ischemia were similar in age, multivessel CAD, previous myocardial infarction, LV EF, LV volumes, and treatment allocation (all p _ NS).

Myocardial ischemia was induced during stress testing in 64 percent of the study population. While patients with ischemia testing had lower LV EF and larger LV volumes, and a higher rate of intracardiac defibrillator use during the study, overall results found no statistical difference between patients with and without ischemia in all-cause mortality (hazard ratio: 1.08; 95% confidence interval: 0.77 to 1.50; p _0.66), cardiovascular mortality, or all-cause mortality plus cardiovascular hospitalization. In addition, there was no interaction between ischemia and treatment for any clinical end point.

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"Despite the trend for decreased overall and cardiovascular mortality for CABG compared with medical therapy, no interaction was found between the treatment effect of surgical revascularization and the presence of ischemia," the investigators said. "In essence, these results suggest that the therapeutic effect of CABG is not limited to patients with inducible myocardial ischemia on stress testing."

Based on the study results, the investigators suggest that the demonstration of myocardial ischemia should not be viewed as a requisite for the indication of surgical revascularization. "If CABG is indicated on the basis of the patient's clinical presentation, it should not be withheld because ischemia is not demonstrated on noninvasive studies," they note. They urge physicians to integrate all available information, including the location of ischemia, the accuracy of imaging stress testing (particularly in patients with severe LV dysfunction and remodeling) and the feasibility of regional revascularization, when determining the best treatment options.

Keywords: Coronary Artery Disease, Myocardial Infarction, Defibrillators, Myocardial Ischemia, Confidence Intervals, Hospitalization, United States, Exercise Test

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