Patients with severe left ventricular (LV) dysfunction and multi-vessel coronary artery disease (CAD) are at high risk during revascularisation, however they are also likely to derive the most benefit. Historically, the detection of dysfunctional but potentially viable myocardium (‘stunned or hibernating myocardium’) has been central to the decision-making regarding revascularisation. A number of recent studies have challenged this paradigm, questioning the role of viability testing in this population. In this review, we will examine the position of viability testing and how it is best incorporated in the modern era of coronary revascularisation. We will outline the role of currently available imaging modalities in viability assessment. Myocardial viability testing will continue to play a role in revascularisation decisions, although larger randomised trials with clinical outcome end-points are needed to further define its role.