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Myocardial Viability and Survival in Ischemic Left Ventricular Dysfunction
Study Questions:
What is the efficacy of myocardial viability in identifying patients with coronary artery disease and left ventricular dysfunction in whom coronary artery bypass grafting (CABG) will provide a survival benefit?
Methods:
In a substudy of patients with coronary artery disease and left ventricular dysfunction who were enrolled in a randomized trial of medical therapy with or without CABG, the investigators used single-photon emission computed tomography (SPECT), dobutamine echocardiography, or both to assess myocardial viability on the basis of prespecified thresholds. Kaplan-Meier curves were used to examine the outcomes in each study group, according to viability status.
Results:
Among the 1,212 patients enrolled in the STICH (Surgical Treatment for Ischemic Heart Failure) randomized trial, 601 underwent assessment of myocardial viability. Of these patients, investigators randomly assigned 298 to receive medical therapy plus CABG, and 303 to receive medical therapy alone. A total of 178 of 487 patients with viable myocardium (37%) and 58 of 114 patients without viable myocardium (51%) died (hazard ratio for death among patients with viable myocardium, 0.64; 95% confidence interval, 0.48-0.86; p = 0.003). However, after adjustment for other baseline variables, this association with mortality was not significant (p = 0.21). There was no significant interaction between viability status and treatment assignment with respect to mortality.
Conclusions:
The authors concluded that the assessment of myocardial viability did not identify patients with a differential survival benefit from CABG.
Perspective:
In this substudy of the STICH trial, the presence of viable myocardium was associated with a greater likelihood of survival in patients with coronary artery disease and left ventricular dysfunction, but this relationship was not significant after adjustment for other baseline variables. The more important finding of this substudy was that there was no significant interaction between myocardial viability and medical versus surgical treatment with respect to survival. The lack of interaction suggests that assessment of myocardial viability alone should not be the deciding factor in selecting the best therapy for these patients. The study findings also highlight the need for prospectively designed studies to determine the role of cardiac imaging in clinical decision making.
Keywords: Coronary Artery Disease, Heart Failure, Myocardium, Coronary Artery Bypass, Ventricular Dysfunction, Left, Echocardiography
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