Pre-infarction angina elicits greater myocardial viability on reperfusion after myocardial infarction: a dobutamine stress echocardiographic study

OBJECTIVES We sought to evaluate myocardial viability (inotropic reserve) after myocardial infarction (MI) and its relationship with the presence of unstable pre-infarction angina (PIA). BACKGROUND Several studies have suggested that PIA can limit infarct size, but it is not known whether PIA can elicit myocardial viability after an acute MI, with left ventricular function improvement. METHODS Before discharge from the hospital, 91 patients with a reperfused MI (either fibrinolysis or primary coronary angioplasty) had low-dose dobutamine echocardiography performed to assess the myocardial inotropic reserve of the infarct-related area. RESULTS Twenty-nine patients (31.9%) had PIA in the 24-h period before the onset of MI. Nine patients were treated with primary coronary angioplasty: five (8.1%) in the group with PIA and four (13.8%) in the group without PIA. There were no other significant differences in the baseline characteristics of the patients. There were more viable segments in patients with PIA (44.9% vs. 30.7%, p = 0.007), and the number of patients with significant viability was higher in the PIA group (73.9% vs. 46.3%, p = 0.026). This occurred despite a similar number of segments with segmental wall abnormalities at baseline in both groups (46.1% vs. 46.9%, p = NS). CONCLUSIONS The presence of previous unstable PIA induces greater myocardial viability of the infarct-related area upon reperfusion and, as such, could have considerable therapeutic and clinical implications.