Inducible myocardial ischemia and outcomes in patients with coronary artery disease and left ventricular dysfunction

Abstract

Objectives: The study objectives were to test the hypotheses that ischemia during stress testing has prognostic value and identifies those 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.

Background: The clinical significance of stress-induced ischemia in patients with CAD and moderately to severely reduced LV ejection fraction (EF) is largely unknown.

Methods: The STICH (Surgical Treatment for IsChemic Heart Failure) trial randomized patients with CAD and EF ≤35% to CABG or medical therapy. In the current study, we 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, LV EF, LV volumes, and treatment allocation (all p = NS). There was no 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. There was no interaction between ischemia and treatment for any clinical endpoint.

Conclusions: 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. (Comparison of Surgical and Medical Treatment for Congestive Heart Failure and Coronary Artery Disease [STICH]; NCT00023595).

Copyright © 2013 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.

Figures

Figure 1. Kaplan-Meier rate estimates of all-cause mortality (panel A), cardiovascular mortality (panel B), and all-cause mortality or cardiovascular hospitalization (panel C)

The 813 STICH patients with no evaluable stress testing and hence excluded from this study are shown on the left panels. The 399 patients with stress testing included in this study are shown on the right panels. Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.

Figure 1. Kaplan-Meier rate estimates of all-cause mortality (panel A), cardiovascular mortality (panel B), and all-cause mortality or cardiovascular hospitalization (panel C)

The 813 STICH patients with no evaluable stress testing and hence excluded from this study are shown on the left panels. The 399 patients with stress testing included in this study are shown on the right panels. Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.

Figure 1. Kaplan-Meier rate estimates of all-cause mortality (panel A), cardiovascular mortality (panel B), and all-cause mortality or cardiovascular hospitalization (panel C)

The 813 STICH patients with no evaluable stress testing and hence excluded from this study are shown on the left panels. The 399 patients with stress testing included in this study are shown on the right panels. Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.

Figure 2. Kaplan-Meier estimates of all-cause mortality rates

Study patients are divided according to the presence or absence of ischemia on stress testing, regardless of treatment allocation.

Figure 3. Kaplan-Meier rate estimates of cardiovascular mortality (panel A) and all-cause mortality plus cardiovascular hospitalization (panel B)

Study patients are divided according to the presence or absence of ischemia on stress testing, regardless of treatment allocation.

Figure 3. Kaplan-Meier rate estimates of cardiovascular mortality (panel A) and all-cause mortality plus cardiovascular hospitalization (panel B)

Study patients are divided according to the presence or absence of ischemia on stress testing, regardless of treatment allocation.

Figure 4. Kaplan-Meier estimates of all-cause mortality rates according to treatment among patients with (right panel) or without (left panel) ischemia

Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.

Figure 5. Kaplan-Meier rate estimates of cardiovascular mortality (panel A) and all-cause mortality plus cardiovascular hospitalization (panel B) according to treatment among patients with (right panels) or without (left panels) ischemia

Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.

Figure 5. Kaplan-Meier rate estimates of cardiovascular mortality (panel A) and all-cause mortality plus cardiovascular hospitalization (panel B) according to treatment among patients with (right panels) or without (left panels) ischemia

Analysis based on intention-to-treat. MED= medical therapy; CABG= coronary artery bypass graft surgery.