The prognosis for patients with chronic ischemic left ventricular
dysfunction is poor, despite advances in different therapies.
Noninvasive assessment of myocardial viability may guide patient
management. Multiple imaging techniques have been
developed to assess viable and nonviable myocardium by evaluating
perfusion, cell membrane integrity, mitochondria, glucose
metabolism, scar tissue, and contractile reserve. PET, 201Tl and
99mTc scintigraphy, and dobutamine stress echocardiography
have been extensively evaluated for assessment of viability
and prediction of clinical outcome after coronary revascularization.
In general, nuclear imaging techniques have a high sensitivity
for the detection of viability, whereas techniques evaluating
contractile reserve have a somewhat lower sensitivity and a
higher specificity. MRI has a high diagnostic accuracy for assessment
of the transmural extent of myocardial scar tissue.
Patients with a substantial amount of dysfunctional but viable
myocardium are likely to benefit from coronary revascularization
and may show improvements in regional and global contractile
function, symptoms, exercise capacity, and long-term prognosis.
Key Words: myocardial viability; heart failure; noninvasive imaging;
prognosis; stunning; hibernation