Prognostic value of dipyridamole echocardiography after a first uncomplicated myocardial infarction

BACKGROUND: TO assess the prognostic value of dipyridamole stress echocardiography in survivors of a first uncomplicated acute myocardial infarction. PATIENTS AND METHODS: A total of 75 patients (68 men, 7 women) aged 58 years (range, 37-77) were studied 3-5 days after a first acute myocardial infarction and followed up for a mean of 10 months. Dipyridamole infusion was administered at high doses: 0.56 mg/kg, adding 0.28 mg/kg if the test was still negative. Two-dimensional echocardiography was continuously recorded during infusion and the test was considered positive if a decrease in regional contractile function appeared and negative if no assynergy was observed up to 15 min after the begining of dipyridamole administration. A wall motion score index of regional function was derived by summation of individual segment scores divided by the number of interpreted segments. This was calculated for rest and peak dipyridamole echocardiograms. Fifty of 75 patients underwent coronary angiography based an clinical criteria. RESULTS: There were 31 coronary events: 4 deaths, one reinfarction, 13 angina. Thirteen patients underwent coronary revascularization (9 bypass and 4 angioplasty). Dipyridamole echocardiography was positive in 29 patients (39%) and negative in 46 patients (61%), Twenty patients (69%) presented coronary events in the group of positive test versus only 11 (24%) of negatives (p = 0.0001). Four patients died in the positive group while none in the negative group. Sensitivity, specificity and accuracy for all cardiac events were 65, 80 and 73%, respectively. Significant variables from univariate analysis were dipyridamole stress echocardiography response, wall motion score index at peak dipyridamole, ischemic changes in EGG and treatment with two or more antianginal drugs. Multivariate analysis showed positive dipyridamole echocardiography as the only independent prognostic factor to predict cardiac events in postmyocardial infarction patients (RR = 2.56; 95% CI = 1.12-5.84). Four of 19 patients with one vessel disease and 17 of 22 patients with 2-3 vessel disease presented a positive dipyridamole test; whereas the test was negative in the remaining nine patients with normal coronary angiography. Conclusion: Dipyridamole stress echocardiography is a safe and feasible pharmacologic stress imaging method to stratify postmyocardial infarction patients at risk of cardiovascular events.