We assessed the safety of early (2 to 4 days) intravenous
dipyridamole infusion in conjunction with
technetium 99m sestamibi tomographic myocardial perfusion imaging in patients with first
myocardial infarction (MI). Early risk stratification with myocardial perfusion imaging of patients after acute MI may be useful to identify patients who either require further evaluation or may be safely discharged. Because of minimal hemodynamic effects, intravenous
dipyridamole may be a safe means of producing
hyperemia for myocardial perfusion imaging. Stable patients with first acute MI who met entry criteria were randomized (3:1) to either intravenous
dipyridamole infusion (0.56 mg/kg over a 4-minute period) 48 to 96 hours after onset of symptoms or a control (no test) group.
Adverse cardiac events (
unstable angina, recurrent MI, or
cardiac death) were evaluated during and 24 hours after the
dipyridamole infusion and during the corresponding 24 hours for the control group. Two hundred eighty-four patients received
dipyridamole infusion a mean time of 3.3 +/- 0.7 days after MI. There were no adverse clinical events either during or immediately after the infusion. During the 24 hours after infusion, three patients had symptoms of
unstable angina pectoris, one patient had a recurrent MI, and no patients died. The earliest event occurred 4.2 hours after the
dipyridamole infusion. Three patients had
unstable angina pectoris, whereas no patients had either recurrent MI or died in the control group. There were no statistically significant differences between the two groups. In a multicenter trial,
dipyridamole infusion administered early after the first acute MI resulted in no increased evidence of
cardiac events either immediately or 24 hours after the procedure compared with a control group. Therefore intravenous
dipyridamole can be safely used as a pharmacologic
vasodilator for myocardial perfusion imaging soon after uncomplicated MI.