Evaluation of Myocardial Viability – Contrast and Stress Echocardiography

Viable myocardium are myocardial segments with reduced function that often appear dyssynergic. These dyssynergic myocardial segments are capable of functional recovery, either spontaneously or after the offending insult, usually ischaemia, is removed by revascularisation. Patients with impaired left ventricular function but with viable myocardium are at increased risk of death and adverse cardiovascular outcome. The detection and recognition of viable myocardium is critical for risk stratification, guiding the selection of patients likely to benefit from revascularisation and predicting left ventricular remodelling. Contrast and stress echocardiography are important clinical tools for the assessment of myocardial viability. An end diastolic wall thickness of <0.6cm at the dyssynergic segments generally indicates scarring. The presence of post-systolic thickening at these segments suggests either myocardial viability or ischaemia. Useful in assessing contractile reserve in dyssynergic segments, dobutamine echocardiography is an established tool for detecting myocardial viability with accuracies comparable to other techniques. A biphasic response is diagnostic and specific for hib