Is viability still viable after the STICH trial?

Stunning and hibernation represent two different forms of tissue viability identifiable in acute coronary syndromes and chronic ischaemic cardiomyopathy, respectively. Functional recovery occurs spontaneously with myocardial stunning, while it generally follows revascularization in case of hibernating myocardium. Low-dose dobutamine stress echocardiography is an accurate modality for identifying myocardial stunning and provides important information on ventricular remodelling after both systemic thrombolysis and primary angioplasty. In patients with conservatively treated infarction, the prognostic significance of viability by dobutamine stress echocardiography correlates with residual pump function. Substantial contractile reserve is predictive of favourable outcome in patients with poor but not in those with preserved or slightly reduced left ventricular function. Non-invasive assessment of coronary flow reserve with transthoracic Doppler echocardiography of the left anterior descending coronary artery allows to distinguish between necrotic and stunned myocardium and predicts ventricular remodelling following primary angioplasty. Resting echocardiographic examination can provide information on hibernating myocardium. In particular, systolic thickening <7 mm, restrictive filling pattern, and high end-systolic volume are predictive of no viability. Compared with nuclear imaging, dobutamine stress echocardiography is more specific for predicting functional recovery, less expensive, more generally available and radiation-free. A large body of evidence collected over the years demonstrates the favourable prognostic impact of revascularizing extensive myocardial territories which are found viable at dobutamine stress echocardiography in patients with ischaemic cardiomyopathy. The prognostic implications of viability-guided revascularization have been clearly established in both diabetic and non-diabetic patients. However, the prognostic value of myocardial viability has been questioned by the results of the STICH trial that did not demonstrate any advantage of survival in the patients with a large extent of myocardial viability undergoing revascularization. Is the end of a paradigm that deeply influenced clinical practice so far or just a neutral result that can be ignored due to the several limitations of study design? In the present review, we will address the main advantages and limitations of ultrasounds for the evaluation of myocardial viability and try to demonstrate that viability is still viable.