[Myocardial viability: when and how to look for it, its prognostic impact and interaction with benefits of...

Ischemic left ventricular dysfunction results from the combination of scar and areas of dysfunctional but viable myocardium that may improve contractile function with revascularization. The traditional paradigm states that an improvement in function after revascularization leads to improved health outcomes and that assessment of myocardial viability has a key role in predicting the benefit of revascularization and, therefore, is a prerequisite for the selection of patients to undergo this treatment option. A range of retrospective observational studies supported this "viability hypothesis". However, randomized prospective trials have not confirmed the interaction between myocardial viability and the treatment effect of revascularization, challenging the recovery of left ventricular function as the principal mechanism by which surgical revascularization improves prognosis. A conceptual shift from the traditional paradigm centered on the assessment of viability as a dichotomous variable to a more comprehensive approach founded on an alternative concept that the main goal of revascularization is to prevent further damage by protecting the residual viable myocardium from subsequent acute coronary events and ventricular arrhythmias is required.