Impact of previous angina before acute myocardial infarction on peak cardiac enzyme levels and clinical outcomes

Purpose: The association between previous angina before acute myocardial infarction (AMI) and clinical outcomes has not been well characterized. Methods: Between January 2005 and September 2008, a total of 13,554 AMI patients enrolled in the Korea Acute Myocardial Infarction Registry were grouped according to previous angina: Group I (no previous angina, n=7,716) and Group II (previous angina, n=5,838). The primary endpoint was the peak level of cardiac enzymes. The secondary endpoint was major adverse cardiac events (MACE), including death, MI, and target lesion revascularization at 12 months. Results: Patients in Group I were younger (62.9±13.0 vs. 64.2±12.4 years, p<0.001); had lower prevalence of diabetes (25.9 vs. 29.9%, p<0.001), hypertension (45.9 vs. 52.9%, p<0.001), a higher Killip class≥II (29.1 vs. 25.6%, p<0.001), stenotic lesions in the right coronary artery, and higher prevalence of 1-vessel coronary artery disease. Group II were more likely to have a lower level of peak creatine kinase (CK) (1494.7±2093.7 vs. 1256.9±1946.6 U/L, p<0.001), CK-MB (154.8±279.3 vs. 120.9±284.3 ng/mL, p<0.001), troponin-I (48.1±112.2 vs. 42.2±156.4 ng/mL, p=0.132). In Group II, there was a trend toward less likely in-hospital death (5.5 vs. 4.9%, p=0.06). During follow-up, however, the rates of composite of MACE at 1, 6, 12 months were not statistically different between the two groups. Conclusion: Patients who experienced previous angina before AMI were more likely to have a smaller cardiac enzyme-determined infarct size. Previous angina confers a beneficial effect on in-hospital outcome after AMI.