Incidence and prognosis of non-Q-wave vs. Q-wave myocardial infarction following catheter-based reperfusion therapy

Abstract

The clinical importance of classifying myocardial infarction (MI) into non-Q-wave (NQWMI) vs. Q-wave (QWMI) subsets is controversial and might depend on the therapeutic reperfusion strategy employed. The prognostic implications of NQWMI development following primary percutaneous coronary intervention (PCI) have not been reported. To examine the incidence, determinants and prognostic implications of NQWMI vs. QWMI development following primary PCI. The ACSIS Registry, a 2-month nationwide survey conducted biennially, prospectively collects data from all MI admissions in Israel. Outcomes were compared among patients managed by primary PCI who subsequently developed NQWMI vs. QWMI. Independent predictors of Q-wave development and 1-year mortality were determined by multivariate stepwise logistic regression analysis and Cox proportional hazard model, respectively. Of 4537 MI patients with ST-segment elevation on admission, 1230 (27%) were treated with primary PCI. A discharge diagnosis of NQWMI was made in 259 (21.1%) patients. The baseline features and PCI strategies employed were similar among NQWMI vs. QWMI patients, though peak creatine kinase levels were higher (median 795 U/l vs. 1681 U/l, P = 0.0001) and severe left ventricular ejection fraction (LVEF) impairment (<40%) more frequent (22.6% vs. 43.9%, P < 0.0001), in the latter group. Mortality at 1-year was significantly lower in NQWMI vs. QWMI patients (3.9% vs. 10.8%, P log-rank = 0.001). By Cox proportional hazard analysis, NQWMI vs. QWMI was an independent predictor of freedom from 1-year mortality [HR = 0.34 (95% CI: 0.15-0.79), P = 0.01]. The diagnosis of NQWMI after primary PCI is associated with an excellent prognosis independent of established prognosticators, including LVEF.