Impact of smoking on acute phase outcomes of myocardial infarction

Objectives Previous studies have found an apparent paradox in smokers: acute phase outcomes after an acute myocardial infarction are superior to those of nonsmokers. Furthermore, it is reported that smoking has an impact on the metabolism of clopidogrel. This study aimed to examine whether this paradoxical finding exists in patients who undergo drug-eluting stent implantation and are treated with clopidogrel. Methods From April 2003 to June 2010, 1424 consecutive patients with acute myocardial infarction who underwent primary or rescue percutaneous coronary intervention with drug-eluting stent and clopidogrel were enrolled. They were divided into three groups: current smokers (n=486); previous smokers (n=349); and nonsmokers (n=589). The primary end point was a composite of 30-day, all-cause death, nonfatal myocardial infarction, or definite stent thrombosis. Results Compared with nonsmokers, current smokers were younger (P<0.001) and more often men (P<0.001). They had larger myocardial infarctions than did nonsmokers [maximum troponin I, 8.9 (2.4, 38.4) vs. 6.8 (1.4, 30.1) ng/ml, P=0.01]. Current smokers less frequently met the primary end point than did nonsmokers (2.9 vs. 6.1%, P=0.01). However, after adjustment for baseline and angiographic characteristics, the beneficial effect of smoking was no longer seen (odds ratio 1.35, confidence interval: 0.53–3.44, P=0.5). Conclusion A beneficial effect of smoking (‘smoker's paradox’) in the unadjusted primary end point continues to be present; however, after adjustment for differences in baseline characteristics, no benefit was detectable.