[Detection of residual ischemia after acute anterior myocardial infarction using Thallium-201 SPECT].

OBJECTIVES

To assess the utility of single photon emission computed tomography (SPECT) with Thallium-201 after anterior myocardial infarction at predischarge time in the detection of; a) the prevalence of isotopic redistribution in the infarct area or at a distance; b) the correlation between peri-infarction ischemia and the angiographic state of the infarct-related artery, and c) the correlation between ischemia at a distance and the presence of multivessel disease.

MATERIAL AND METHOD

Seventy-three survivors of an uncomplicated anterior myocardial infarction, 67 men and 7 women, with a mean age of 56 +/- 9 years (34-70 range), underwent T1-SPECT after stress test (62 exercise test and 11 pharmacological Dipyridamole test) as well as coronarographic studies before discharge. Peri-infarction ischemia was defined as redistribution presence in the distribution territory of the left anterior descending artery (LAD) and was assessed in a semi-quantitative way scoring both stress and rest images that allowed the calculation of a redistribution index R (Stress Score-Rest Score/Stress Score). Ischemia at a distance was defined as redistribution presence in the territories of circumflex and right coronary arteries as assessed both by visual analysis (VA) and bull's eye polar maps (BE) or by washout imaging (WO).

RESULTS

Peri-infarction ischemia (R > 0) was found in 48 (65.7%) patients; 43 with and 5 without significant residual lesions in the LAD and the absence of peri-infarction ischemia (R = 0) was found in 25 (34.3%) patients, 19 with and 6 without significant residual lesions in the LAD. Sensitivity and specificity for multivessel disease detection by ischemia at a distance was 64% and 85% respectively, for VA; 60% and 77% for BE; and 95% and 65% for WO. Combinations of different analytical methods (multiparametric approach) showed a decrease in sensitivity but improved specificity and positive predictive value: 60%, 90% and 75%, respectively, for BE & WO; 44%, 90% and 69% for VA & BE and 60%, 92% and 79% for VA & WO.

CONCLUSIONS

TI-SPECT imaging is a useful diagnostic method to detect both peri-infarction ischemia and ischemia at a distance at predischarge time following anterior myocardial infarction. Redistribution presence in the non infarct-area shows a fair sensitivity and a high positive predictive value to detect residual multivessel disease.