The impact of circadian variation on outcomes in emergency acute anterior myocardial infarction percutaneous coronary intervention

Objectives: We investigated the impact of primary coronary angioplasty performed during night and compared to the impact of that performed during day-time on outcomes of patients with acute ST elevation anterior wall myocardial infarction (AMI). Methods: We prospectively followed 273 consecutive patients of whom 160 (58.6%) were treated during day time (8:00 a.m. to 6 p.m.) and 113 (41.4%) were treated "off hours"/at night (6 p.m. to 8 a.m.). Baseline demographics, angiographic factors, and clinical outcomes (death, recurrent AMI, and need for repeat revascularization) were compared between the groups. Results: Baseline clinical characteristics were similar between the two groups. Unadjusted mortality at one-month was significantly higher among patients who were treated during night compared with those treated at day-time (9.7% vs. 3.1% P = 0.03), as was adverse cardiac event rate (15.9% vs. 6.9%; P = 0.02). Multiple logistic regression analysis adjusted for the CADILLAC risk score demonstrated that this score, which includes baseline LVEF, renal failure, Killip class, final TIMI flow, age > 65 years, anemia, and the number of coronary vessel diseases, is a significant predictor of one-month mortality, while the effect of time of treatment was borderline (night vs. day; odds ratio 2.7; 95% confidence interval, 0.8-9.4; P = 0.095). Conclusions: The results of this study indicate that patients with anterior myocardial infarction treated during night time have worse unadjusted short-term clinical outcomes despite no delay from onset of symptoms to actual treatment. Larger studies are needed in order to identify potential contributors to this phenomenon. (c) 2006 Wiley-Liss, Inc.