CLINICAL INVESTIGATIONS Dobutamine-Induced Contractile Reserve in

Because of damage to cardiomyocytes and the contractile appa-ratus, contractile reserve may be observed less frequently in hi-bernating than in stunned myocardium. The aim of this study was to assess the presence of contractile reserve in response to do-butamine infusion in a large group of patients with stunned and hibernating myocardium. Methods: A total of 198 consecutive patients with ischemic cardiomyopathy (left ventricular ejection fraction 40%) underwent resting 2-dimensional echocardiogra-phy to assess regional contractile dysfunction. On the basis of assessment of perfusion (with 99mTc-tetrofosmin SPECT) and glu-cose use (with 18F-FDG SPECT), dysfunctional segments were grouped. Dysfunctional segments with normal perfusion were classified as stunned. Dysfunctional segments with a perfusion defect were classified as hibernating when a perfusion–18F-FDG mismatch was present. Dysfunctional segments with a perfusio