Diabetes mellitus prevents ischemic preconditioning in patients with a first acute anterior wall myocardial infarction

OBJECTIVES This study was undertaken to assess whether prodromal angina could have beneficial effects in diabetic patients with acute myocardial infarction (AMI). BACKGROUND Prodromal angina occurring shortly before the onset of AMI is associated with favorable outcomes by the mechanism of ischemic preconditioning. However, little is known about the impact of diabetes on ischemic preconditioning. METHODS We studied 611 patients with a first anterior wall AMI who underwent emergency catheterization within 12 h after the onset of chest pain: 490 patients without diabetes and 121 patients with non–insulin treated diabetes. Prodromal angina was defined as angina episode(s) occurring within 24 h before the onset of AMI. Serial contrast left ventriculograms were obtained in 424 patients at the time of acute and predischarge catheterization. RESULTS In non-diabetic patients, prodromal angina was associated with lower peak creatine kinase (CK) value (3,068 ± 2,647 IU/l vs. 3,601 ± 2,462 IU/l, P = 0.037), larger increase in left ventricular ejection fraction (LVEF) (10.1 ± 13.0% vs. 5.8 ± 13.4%, P = 0.004) and lower in-hospital mortality (3.4% vs. 9.3%, P = 0.015). On the contrary, in diabetic patients, there was no significant difference in peak CK value (3,382 ± 2,520 IU/l vs. 3,233 ± 2,412 IU/l, P = NS), the change in LVEF (6.7 ± 13.8% vs. 7.1 ± 12.4%, P = NS) and in-hospital mortality (8.8% vs. 11.0%, P = NS) between patients with and patients without prodromal angina. CONCLUSIONS Prodromal angina limited infarct size, enhanced recovery of LV function and improved survival in non-diabetic patients with AMI. However, such beneficial effects of prodromal angina were not observed in diabetic patients, suggesting that diabetes might prevent ischemic preconditioning.