Comparison of approaches in the assessment of myocardial viability and follow-up of PTCA/CABG. The role of echocardiography.

Dysfunctional myocardium may be viable in patients with acute myocardial infarction. Although viable but dyssynergic myocardium may be recognized a posteriori by the occurrence of functional recovery, prospective identification of the actual myocardial state is more important for optimal therapeutic management. Echocardiography during pharmacological interventions is a useful clinical tool, as changes in regional myocardial thickening may be continuously monitored. Stunned myocardium exhibits contractile dysfunction after an ischemic episode despite normalized or near normalized myocardial flow, but stunned myocardium retains contractile reserve. It may be identified by improvement in contractility during a low dose dobutamine infusion in segments showing a mismatch between normal perfusion and reduced contractility. In regions of viable but stunned myocardium corresponding to an artery with reduced coronary flow reserve, contractility may improve at low dose dobutamine infusion and may later deteriorate at high dose, indicating the presence of jeopardized myocardium. Ischemia at a distance observed with dobutamine indicates the presence of multivessel coronary artery disease. These informations are useful for clinical decision making.