Reassessment of contractile reserve after revascularization of akinetic myocardium

In postinfarction patients with left ventricular dysfunction, revascularization of infarct zones may provide varying benefit in exercise capacity, not strictly related to changes in rest left ventricular function. To investigate whether this effect may be related to changes in contractile reserve of infarct zones, we performed, in patients with previous myocardial infarction undergoing bypass surgery or coronary angioplasty, dobutamine stress echocardiography before and after revascularization. Before and > 3 months after revascularization, we performed dobutamine stress echocardiography (low-dose and high-dose) in 21 patients with old Q-wave myocardial infarction (anterior in 11, inferior in 1, and anterior plus inferior in 9) and at least one revascularizing infarct zone. Before revascularization, a total of 175 (64.8%) dyssynergic infarct zone segments were found at baseline. At low-dose dobutamine, 14 infarct zones showed and 16 did not show contractile reserve, contraction improved in 38.1% and 4.2% of segments in infarct zones with and without contractile reserve, respectively (p < 0.001). At high-dose dobutamine, contraction worsened in 42.1% and 16.7% of segments in infarct zones with and without contractile reserve, respectively (p < 0.001). After revascularization, functional recovery occurred in 9 infarct zones [28 segments (22.2%)], of which 8 had shown contractile reserve before revascularization. At low-dose dobutamine, contractile reserve was elicited in 19 infarct zones; wall motion improved in 46.8% and 15.3% of segments in infarct zones with and without contractile reserve before revascularization, respectively (p < 0.001). At high-dose dobutamine, wall motion worsening was practically abolished in both infarct zones with and without contractile reserve. In conclusion, infarct zones with contractile reserve before revascularization, in addition to varying gain in rest function, retain contractile reserve after revascularization. Infarct zones without contractile reserve before revascularization may develop some contractile reserve after revascularization.