Dose and test for dipyridamole infusion and cardiac imaging early after uncomplicated acute myocardial infarction.

To evaluate the relation of the dose of intravenous dipyridamole on results of thallium and echocardiographic testing, the results of standard- (0.56 mg/kg/4 minutes) versus high- (0.84 mg/kg/10 minutes) dose dipyridamole were obtained 9 +/- 3 days after uncomplicated acute myocardial infarction in 57 patients. New wall motion abnormalities were compared with redistribution of thallium imaging and results of discharge coronary angiography. The sensitivity of thallium in predicting the presence of multivessel coronary artery disease was significantly (p < 0.01) higher (85%) than echocardiography (53%) and was unaffected by the dose. However the sensitivity of echocardiography was better with the higher dose (53 vs 14%). Minor adverse effects occurred in 34 patients (59%) after receiving the high dose and only in 4 patients (7%) after the standard dose (p < 0.001). Thus, thallium-201 scintigraphy during standard-dose dipyridamole infusion is more effective than high-dose dipyridamole echocardiographic testing in safely identifying patients who could benefit from early invasive evaluation and therapy.

[Myocardial scintigraphy using 201-thallium and 2-dimensional echocardiogram after dipyridamole infusion in the early evaluation of post-infarct residual ischemia]. / La scintigrafia miocardica con tallio-201 e l'ecocardiogramma bidimensionale dopo infusione di dipiridamolo nella valutazione precoce dell'ischemia residua post-infartuale.

Dipyridamole thallium scintigraphy (TI-DP) and dipyridamole two-dimensional echocardiography (Echo-DP) were performed on 38 patients (pts), 11 +/- 4 days after acute myocardial infarction. Our study intends to assess whether or not imaging methods are useful both in identifying residual jeopardized myocardium and in selecting pts for coronary angiography. No serious side effects were induced during the DP test. In 11 pts angina was not induced, worsening of wall motion abnormalities was not detected on Echo-DP; no reversible defects were found on TI-DP. The remaining 27 pts who showed transient defects on TI-DP underwent coronary angiography. All pts had either multivessel coronary disease or severe single-vessel disease and myocardial revascularisation was performed in all of them. Of these 27 patients, only 5 suffered angina and showed ST-T depression; only in 15 dyskinetic wall motion development was detected on Echo-DP. Finally we can conclude: the DP-test can be safely performed in the early post-infarction period; both the reported imaging methods enable the identification of jeopardized myocardium even if with different ranges of sensitivity; pts negative to both TI-DP and Echo-DP can be safely followed without coronary angiography; pts with transient defects on TI-DP can be reasonably referred to coronary angiography.