PREVIOUS ANGINA ALTERS IN-HOSPITAL OUTCOME IN TIMI-4 - A CLINICAL CORRELATE TO PRECONDITIONING

Background Ischemic preconditioning has been shown to reduce myocardia l infarct size in experimental models, but its role in patients remain s unclear. Angina before myocardial infarction reflects brief episodes of ischemia and may be a marker of preconditioning. As part of the Th rombolysis in Myocardial Infarction (TIMI) 4 study, we performed an an alysis on the effect of a history of previous angina on in-hospital ou tcomes for patients with acute myocardial infarction. Methods and Resu lts Patients eligible for thrombolytic therapy were enrolled into the study. Data were collected from case report forms regarding previous h istory of angina, in-hospital outcome and 6-week follow-up. Two hundre d eighteen patients had a history of previous angina at any time befor e acute myocardial infarction, and 198 patients did not have previous angina. Patients with any previous history of angina were less likely than with those without angina to experience in-hospital death (3% ver sus 8%) (P = .03), severe congestive heart failure (CHF) or shock (1% versus 7%, P = .006), or the combined en d point of in-hospital death, severe CHF, or shock (4% versus 12%, P = .004). Moreover, patients wi th any history of angina were more likely to have a smaller creatine k inase (CK)-determined infarct size (119 versus 154 CK integrated units ; P = .01) and were less likely to have Q waves on their ECG (57% vers us 69%; P = .01). In the subset of patients who experienced angina wit hin the 48 hours before infarction (compared with those who did not), there was a trend toward less likely in-hospital death (3% versus 6%; P = .09), a lower incidence of severe CHF or shock (1% versus 6% P = . 008), a lower combined end point of death, CHF, or shock (3% versus 10 %; P = .006), smaller infarct size assessed by CK (115 versus 151 CK u nits; P = .03), and a trend toward fewer Q-wave infarcts. However, pat ients with a history of previous angina did have a trend toward mole r ecurrent ischemic pain. Of importance is that the beneficial in-hospit al effects of previous angina were not dependent on angiographically v isible coronary collaterals. Conclusions Previous angina confers a ben eficial effect on in-hospital outcome after acute myocardial infarctio n. The reasons for this benefit are uncertain, but one potential mecha nism for this observation may be ischemic preconditioning.