Myocardial viability in patients with coronary artery disease and left ventricular dysfunction: transplantation or revascularization?

Coronary artery bypass surgery performed in patients with coronary artery disease and left ventricular dysfunction improves survival compared with antianginal therapy alone. The mechanisms for this survival advantage with revascularization therapy have not been systematically elucidated. Many of these patients have "hibernating" myocardium secondary to chronic ischemia with the potential for substantial improvement in left ventricular function and heart failure symptoms following revascularization therapy. Nevertheless, as survival with cardiac transplantation continues to improve, a significantly larger number of patients with coronary artery disease and left ventricular dysfunction are being referred for cardiac transplantation in lieu of revascularization surgery. Recently developed imaging modalities, which include positron emission tomography, thallium imaging, and dobutamine echocardiography, can reliably predict recovery of regional myocardial dysfunction after revascularization in these areas of hibernating heart. New modalities to detect hibernating myocardium include 99mTc-sestamibi, contrast echocardiography, nuclear magnetic resonance spectroscopic imaging, and ultrasonic tissue characterization. In an era of medicine characterized by increased concern for cost containment and the judicious application of expensive technology, the choice of the most appropriate tests to detect viability is a growing challenge and is essential in the choice between transplantation and revascularization.