The relevance of brief antecedent ischemia to preservation of myocyte viability and cardiac function is still controversial in humans. Dysfunctioning but viable myocardium shows impaired fatty acid metabolism despite restored coronary perfusion. We asked whether preinfarction angina might be related to preservation of cell viability and better functional recovery in comparison with impaired fatty acid metabolism. METHODS Tomographic imagings with thallium and beta-methyl-p-iodophenyl penta-decanoic acid (BMIPP) were performed in 32 patients with first acute myocardial infarction who received primary coronary angioplasty: 20 patients with preexisting angina before infarction (Group A) and 12 without (Group B). Thallium and BMIPP abnormalities were quantified as a severity index by a polar map. Regional function was quantified by ventriculography and followed up. RESULTS Despite no significant difference in coronary risk factors, cardiac function and angiographic findings, the thallium severity index was significantly lower than that of BMIPP (62+/-45 versus 96+/-59) in Group A but not in Group B (104+/-65 versus 115+/-68); the thallium severity index in Group A was significantly lower than that in Group B, but there was no significant difference in BMIPP abnormality between them. The BMIPP severity index correlated significantly with that of thallium in both groups. However, the regression line in Group A shifted downward and was statistically different compared with that in Group B. Regional function at an acute stage was significantly improved from 107+/-31 to 70+/-31 s.d./chord during follow-up in Group A but not in Group B (109+/-62 versus 106+/-52). The ratio of the thallium severity index to that of BMIPP at an acute stage was significantly related to improved regional wall motion during follow-up in the reperfused patients (y=-53x + 65, r=0.667). CONCLUSIONS Preinfarction angina preserves myocyte viability relative to fatty acid metabolism, resulting in augmented perfusion-metabolism mismatch and functional improvement in patients undergoing successful reperfusion, indicating cardioprotective effects of preinfarction angina.