ANGINA-INDUCED PROTECTION AGAINST MYOCARDIAL-INFARCTION IN ADULT AND ELDERLY PATIENTS - A LOSS OF PRECONDITIONING MECHANISM IN THE AGING HEART

Objectives. The present study examined whether angina 48 h before myoc ardial infarction provides protection in adult and elderly patients. B ackground. The mortality rate for coronary artery disease is greater i n elderly than in young patients. In experimental studies, ischemic pr econditioning affords an endogenous form of protection against ischemi a-reperfusion injury in adult but not in senescent hearts. Angina befo re myocardial infarction, a clinical equivalent of experimental ischem ic preconditioning, has a protective effect in adult patients. It is n ot known whether angina before myocardial infarction is also protectiv e in aged patients. Methods. We retrospectively verified whether antec edent angina within 48 h of myocardial infarction exerts a beneficial effect on in-hospital outcomes in adult (<65 years old, n = 293) and e lderly (greater than or equal to 65 years old, n = 210) patients. Resu lts. In-hospital death was more frequent in adult patients without tha n in those with previous angina (10% vs. 2.6%, p < 0.01), as were cong estive heart failure or shock (10.7% vs. 33%, p < 0.02) and the combin ed end points (in-hospital death and congestive heart failure or shock ) (20.7% vs. 5.9%, p < 0.0003). In contrast, the presence or absence o f previous angina before acute myocardial infarction in elderly patien ts seems not to influence the incidence of in-hospital death (14.4% vs . 15.2%, p = 0.97), congestive heart failure or shock (11.0% vs. 11.9% , p = 0.99) and the combined end points (25.4% vs. 27.1%, p = 0.89). L ogistic regression analysis models for in-hospital end points show tha t previous angina is a positive predictor in adult but not in elderly patients. Conclusions. The presence of angina before acute myocardial infarction seems to confer protection against in-hospital outcomes in adults; this effect seemed to be less obvious in elderly patients. Thi s study suggests that the protection afforded by angina in adult patie nts may involve the occurrence of ischemic preconditioning, which seem s to be lost in senescent patients. (C) 1997 by the American College o f Cardiology.