Abstract 14889: Inducible Myocardial Ischemia and Outcomes in Patients with Coronary Artery Disease and Left Ventricular Dysfunction Treated with Medical Therapy or Surgical Revascularization. A Report from the STICH Trial
Background: The clinical significance of stress-induced ischemia in patients with coronary artery disease (CAD) and moderately to severely reduced left ventricular (LV) ejection fraction (EF) is largely unknown. Hence, we tested the hypotheses that ischemia during stress testing has prognostic value and identifies those CAD patients with LV dysfunction who derive the greatest benefit from coronary bypass graft surgery (CABG) compared to medical therapy alone (MED).
Methods: The STICH trial revascularization hypothesis randomized 1,212 patients with CAD and EF ≤35% to CABG or MED. In this study, we included those patients who had either a radionuclide (RN) stress test or a dobutamine stress echocardiogram (DSE) within 90 days of randomization. A test was considered positive for ischemia by RN if >5% of the myocardium was ischemic (using difference in tracer activity between rest and stress) or if there were ≥2 of 16 ischemic segments during DSE. Ischemia was also examined as a continuous variable using the RN percent of ischemic myocardium or the number of ischemic segments during DSE. Clinical endpoints were assessed by intention-to-treat during a median follow-up of 56 months.
Results: Of the 399 patients included (33% of those in the STICH revascularization hypothesis), 197 were randomized to CABG and 202 to MED. Myocardial ischemia during stress testing was detected in 256 patients (64% of the study population). Patients with and without ischemia were similar in age, presence of multi-vessel CAD, previous myocardial infarction, LV EF, LV volumes, and treatment allocation (all p=NS). There was no difference among patients with vs. without ischemia in all-cause mortality (hazard ratio: 1.08; 95% CI: 0.77-1.50; p=0.66), cardiovascular mortality, or all-cause mortality plus cardiovascular hospitalization. There was no interaction between the presence of ischemia and treatment effect of CABG for any of the clinical endpoints. Assessment of ischemia as a continuous variable and analyses using RN or DSE data separately provided similar results.
Conclusions: In patients with CAD and moderate to severe LV dysfunction, the presence of myocardial ischemia does not identify those with worse prognosis nor those with greater benefit from CABG compared to MED.
- © 2012 by American Heart Association, Inc.