The Doppler myocardial performance index during low-dose dobutamine echocardiography predicts mortality and left ventricular dilation after a first acute myocardial infarction

Background Myocardial viability can be detected by wall motion analysis during low-dose dobutamine echocardiography (LDDE) after acute myocardial infarction (AMI). However, wall motion analysis describes only left ventricular (LV) systolic reserve. The Doppler myocardial performance index (MPI) is a quantitative measure of combined LV systolic and diastolic function. We hypothesized that an increase (deterioration) in MPI during LDDE, reflecting reduced systolic and diastolic LV reserve, could provide prognostic information beyond conventional systolic wall motion analysis on mortality, morbidity, and LV remodeling after AMI. Methods Low-dose dobutamine echocardiography (10 μg/kg per minute) was performed within 24 hours and echocardiography was repeated 5 days and 1, 3, and 6 months after a first AMI in 162 consecutive patients. Patients were followed for 25 ± 11 months. End points were all-cause mortality and cardiac events (cardiac death or readmission for heart failure or reinfarction). Results In 72 (44%) patients, MPI increased during LDDE. This was independently associated with subsequent LV dilation at 6 months of follow-up (β = .73, P < .0001). An increase in MPI during LDDE was a powerful prognostic indicator and remained a predictor of mortality (HR 1.92, 95% CI 1.36-2.71, P < .0001) and cardiac events (HR 2.45, 95% CI 1.83-3.27, P < .0001) after adjustment for clinical data, indices of LV function at rest, and wall motion analysis during LDDE. Conclusions Early after AMI, deterioration in MPI during LDDE predicts subsequent LV dilation and provides prognostic information incremental to clinical data, indices of LV function at rest, and conventional stress echocardiographic data.