BACKGROUND: Echocardiographically recognized resting function, myocardial viability (by low-dose dobutamine) and stress-induced ischemia (by high-dose dipyridamole) are potent predictors of subsequent events, but their relative value in patients evaluated very early after acute myocardial infarction remains to be established. AIM OF THE STUDY: To assess the feasibility end usefulness of an integrated approach with resting and pharmacological stress echo for risk stratification in patients evaluated very early after myocardial infarction. METHODS: Sixty acute myocardial infarction patients without contraindications to stress testing, and who were being given thrombolytic therapy, underwent resting echo (16-segment model of left ventricle, each segment scored from 1 = normo-hyperkinetic to 4 = dyskinetic), high-dose dipyridamole (up to 0.84 mg/kg over 10') and low-dose debutamine (up to 10 mcg/kg/min) echo on the third-fourth day after drug withdrawal. The response was 'ischemic' with a dipyridamole-induced increase in the regional score > 1 in segments with a resting score <3, and 'viable' with a dobutamine-induced decrease in the regional score > 1 in segments with resting score > 1. All patients underwent coronary angiography on the tenth- twelfth day after the acute event, and all of them were followed up for 15 ± 10.04 months. RESULTS: Ischemia elicited by dipyridamole appeared in 29 patients (48%) and dobutamine-induced viability was observed in 28 (47%). Ischemic events occurred in 26 patients (43.4%), five of which during the early in-hospital period. There were three deaths (5%), one re-AMI (1.7%), 7 Canadian Class III-IV angina (12%) and 15 (25%) early revascularization procedures undertaken independently of stress echo results. Events occurred in 21 patients (72%) with dipyridamole-induced ischemia and in 5 (16%) without it (p <0.001). Likewise, events occurred in 13 patients (46.4%) with dobutamine-induced inotropic recovery and in 13 (40.6%) without it (p = ns). Event-free survival occurred in 64% of dipyridamole-positive patients, as opposed to 90% of dipyridamole-negative patients (p = 0.025). Dipyridamole echocardiographic test sensitivity and specificity for events were 81 and 74%, respectively. Sensitivity and specificity for events of dobutamine viability were 46 and 55%, respectively. In a multivariate logistic analysis, dipyridamole-induced myocardial ischemia was the strongest predictor of subsequent events (p = 0.01). According to Cox analysis, dipyridamole positivity had a relative risk estimate of 4. CONCLUSIONS: Pharmacological stress echo is feasible even very early after acute myocardial infarction via a useful approach based on low-dose dobutamine to assess myocardial viability, and high-dose dipyridamole to assess ischemia. For risk stratification purposes, stress-induced myocardial ischemia outperforms resting function and myocardial viability, and it is independent of angiographic data. Revascularization procedures do not seem to be effective when only viability is present.
|Number of pages||8|
|Journal||Giornale Italiano di Cardiologia|
|Publication status||Published - Oct 1997|
- Stress echocardiography
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine