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Inducible Myocardial Ischemia and Outcomes in Patients With Coronary Artery Disease and Left Ventricular Dysfunction
Study Questions:
What is the prognostic value of ischemia during stress testing in identifying patients with coronary artery disease (CAD) with left ventricular (LV) dysfunction who derive the greatest benefit from coronary artery bypass grafting (CABG) compared with medical therapy?
Methods:
The STICH (Surgical Treatment of IsChemic Heart Failure) trial randomized patients with CAD and ejection fraction (EF) ≤35% to CABG or medical therapy. In the current study, the investigators assessed the outcomes of those STICH patients who underwent a radionuclide (RN) stress test or a dobutamine stress echocardiogram (DSE). A test was considered positive for ischemia by RN testing if the summed difference score (difference in tracer activity between stress and rest) was ≥4 or if ≥2 of 16 segments were ischemic during DSE. Clinical endpoints were assessed by intention to treat during a median follow-up of 56 months.
Results:
Of the 399 study patients (51 women, mean EF 26 ± 8%), 197 were randomized to CABG and 202 were randomized to medical therapy. Myocardial ischemia was induced during stress testing in 256 patients (64% of the study population). Patients with and without ischemia were similar in age, multivessel CAD, previous myocardial infarction, LVEF, LV volumes, and treatment allocation (all p = not significant). There was no difference between patients with and without ischemia in all-cause mortality (hazard ratio, 1.08; 95% confidence interval, 0.77-1.50; p = 0.66), cardiovascular mortality, or all-cause mortality plus cardiovascular hospitalization. There was no interaction between ischemia and treatment for any clinical endpoint.
Conclusions:
The authors concluded that in CAD with severe LV dysfunction, inducible myocardial ischemia does not identify patients with worse prognosis or those with greater benefit from CABG over optimal medical therapy.
Perspective:
This study results suggest that the presence of inducible ischemia in patients with CAD and severe LV dysfunction is not associated with worse prognosis and does not identify those with greater therapeutic benefit from surgical revascularization. There was no interaction between the treatment effect of surgical revascularization and the presence of ischemia, and the results suggest that the therapeutic benefit of CABG is not limited to only patients with inducible myocardial ischemia on stress testing. When making clinical decisions, the multidisciplinary physician team must integrate all available information, including the location of ischemia, the possibility of imaging artifacts affecting the accuracy of the test, the feasibility of revascularization, and patient preference to formulate the best therapeutic choice for each individual.
Keywords: Prognosis, Coronary Artery Disease, Myocardial Ischemia, Dobutamine, Follow-Up Studies, Echocardiography, Stress, Heart Failure, Confidence Intervals, Coronary Artery Bypass, Ventricular Dysfunction, Left, Artifacts, Exercise Test
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