[Evaluation of ischemic preconditioning on collateral circulation, ventricular function and clinical outcome in acute myocardial infarction]. / Valor do precondicionamento isquêmico na circulação colateral, função ventricular e evolução clínica no infarto agudo do miocárdio.

PURPOSE: To evaluate the influence of ischemic preconditioning (IP) in collateral circulation (CC), early ventricular function and in hospital outcomes after myocardial infarction (MI). METHODS: We studied 97 patients with a 1st anterior MI within 6h of pain and isolated total proximal occlusion of the left anterior descending artery, divided in 2 groups: with (GA) or without (GB) angina before MI. Coronariography and ventriculography were performed prior to reperfusion. The left ventricular (LV) ejection fraction was measured by the area length method and anterior wall motion by the centerline method. RESULTS: There was no difference between the two groups in sex, age, CKMB level, treatment, reperfusion rate. Global LV ejection fraction and anterior wall motion were similar, respectively, 39 +/- 9% and -2.55 +/- 1.17 SD/chord for GA and 37 +/- 8% and -2.75 +/- 0.79 and -2.75 +/- 0.79 SD/chord for GB (p = ns). The incidence of visible CC to the infarct area was also similar (present in 6 GA vs 8 GB patients). However, GA patients fared significantly better during hospitalization: No GA patient presented Killip class > or = 2 compared to 8 GB patients (p = 0.007). CONCLUSION: Although collateral coronary circulation grades, global and regional LV function were similar between the two groups, the presence of angina pectoris preceding an acute myocardial infarction was associated with a better in hospital evolution, what could be partially explained by preconditioning phoenomena.