RESUMO
INTRODUCTION: Ischemic preconditioning is a phenomenon in which brief episodes of ischemia and reperfusion increase myocardial tolerance and substantially reduce the infarction size. CASE REPORT: Two patients with acute left anterior descending artery occlusion received fibrinolytic therapy within 6 hours of symptom onset, but nevertheless developed myocardial infarctions of different size. The first patient, without a history of preinfarction angina, developed a large anterior infarction, because there was no time for ischemic preconditioning or development of coronary collateral vessels. The second patient, with a 4-day history of preinfarction angina, had a more favorable outcome - he developed apical necrosis, with greater myocardial viability in the infarct-related area. CONCLUSION: The beneficial effects of angina occurring 24-48h before infarction are resulting from ischemic preconditioning, which reduces cardiac mortality, infarct size and occurrence of life-threatening ventricular arrhythmias.
