Evidence of ischemic preconditioning in patients experiencing first non-ST-segment elevation myocardial infarction...

Several studies have demonstrated the protective effects of preinfarction angina in Q wave myocardial infarction, implicating the role of ischemic preconditioning but this role remains uncertain in patients with a NSTEMI. Subendocardial viability in NSTEMI patients, is thought to be less dependent on collateral circulation and thus more likely to be protected by other mechanisms such as preconditioning.

We have studied prospectively 40 patients with first NSTEMI and with angiographically proven poor or no collateral development and compared two groups; those with versus those without preinfarction angina. All in-hospital events, such as recurrent angina, congestive heart failure, arrhythmias and reinfarction were recorded. Serum markers of myocardial necrosis (CPK, CPK-MB, AST) and discharge QTc values were estimated.

Preconditioned patients suffered less recurrent angina (18 vs. 55% P=0.014), congestive heart failure (0 vs. 22%, P=0.02), arrhythmic events (0 vs. 27%, P=0.008) and had significant smaller values of mean peak CPK (381 +/- 152 vs. 859 +/- 496 I.U./l, P=0.0008), mean peak CPK-MB (45.5 +/- 24.6 vs. 105.2 +/- 87 I.U./l, P=0.01), mean peak AST (59.8 +/- 23.1 vs. 112.4 +/- 64.3 I.U./l, P=0.003) and QTc value at discharge (0.42 +/- 0.03 vs. 0.46 +/- 0.05 s, P=0.005) than patients without preconditioning. Multiple logistic regression analysis confirmed that the absence of preinfarction angina (relative risk 9.10, 95% CI 2.08-40.00, P=0.003) was a significant predictor of in-hospital complications.

Preinfarction angina constitutes a strong clinical correlate to ischemic preconditioning in patients with first NSTEMI, offering serious protection, by improving in-hospital outcome and reducing infarct size.