[The echo-stress test with dipyridamole-atropine on the 3rd-5th day of an uncomplicated acute myocardial infarct for risk stratification and early discharge].

Background: The aim of this study was to evaluate if dipyridamole-atropine stress echocardiography (DASE) performed between the third-fifth day in uncomplicated acute myocardial infarction allows for an effective risk stratification with an early discharge in some cases.
Methods: Between February 1997 and September 1998, 190 patients (138 males and 52 females, mean age 59 +/- 10.3 years), with acute myocardial infarction, were enrolled in the study. DASE was performed between the third-fifth day with a dipyridamole infusion of 0.84 mg/kg over 10 min followed by 1 mg of atropine from the twelfth to the fifteenth minute. DASE was considered positive in the presence of a new or worsening dyssynergy. Patients with heart failure, angina, major arrhythmias, and poor acoustic window were excluded. In the follow-up spontaneous events were defined as cardiac death, non-fatal myocardial reinfarction, unstable angina or heart failure (with hospitalization).
Results: DASE was performed in 92 patients (48.4%), all without complications: 29 patients (31.5%) had a negative DASE result, and 63 patients (68.5%) had a positive DASE. The average hospital stay of patients with a negative test was significantly lower in comparison with that of patients with a positive test (7.55 +/- 1.32 vs 9.29 +/- 1.61 days, p < 0.0001). Events occurred in 19 patients (20.6%), 2/29 patients with a negative DASE (6.9%), 17/63 patients with a positive DASE (27%), 6/43 patients with homozonal positivity after atropine or high-dose dipyridamole (14%), 11/20 patients with heterozonal positivity or homozonal positivity after low-dose dipyridamole (55%). On univariate analysis the variables significantly associated with spontaneous events were: age (chi 2 = 6.41, p = 0.019), left ventricular ejection fraction at rest (chi 2 = 8.89, p = 0.004), number of asynergic segments after stress (chi 2 = 6.87, p = 0.010), increase in the number of asynergic segments after stress (chi 2 = 4.01, p = 0.039), wall motion score index after stress (chi 2 = 9.60, p = 0.003), increase in wall motion score index after stress (chi 2 = 3.60, p = 0.049), DASE positivity (chi 2 = 4.89, p = 0.029), homozonal positivity after low-dose dipyridamole (chi 2 = 8.57, p = 0.013), heterozonal positivity (chi 2 = 13.10, p = 0.001). On Cox's multivariate analysis independent predictors of events were: age (relative risk 3.92, p = 0.0146), DASE positivity (relative risk 1.79, p = 0.0054).
Conclusions: DASE between the third-fifth day in uncomplicated acute myocardial infarction is feasible, tolerable, safe, and effective for early risk stratification. A negative DASE detects a "very low-risk" patient group, and allows for an earlier hospital discharge, without an increased risk of events. The heterozonal positivity or the homozonal positivity after low-dose dipyridamole indicates the need for a coronarography, due to the high risk of events at follow-up.