Smoker's Paradox in Patients With ST‐Segment Elevation Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention

Abstract

BackgroundPrior studies have found that smokers undergoing thrombolytic therapy for ST‐segment elevation myocardial infarction have lower in‐hospital mortality than nonsmokers, a phenomenon called the “smoker's paradox.” Evidence, however, has been conflicting regarding whether this paradoxical association persists in the era of primary percutaneous coronary intervention.Methods and ResultsWe used the 2003–2012 National Inpatient Sample databases to identify all patients aged ≥18 years who underwent primary percutaneous coronary intervention for ST‐segment elevation myocardial infarction. Multivariable logistic regression was used to compare in‐hospital mortality between smokers (current and former) and nonsmokers. Of the 985 174 patients with ST‐segment elevation myocardial infarction undergoing primary percutaneous coronary intervention, 438 954 (44.6%) were smokers. Smokers were younger, were more often men, and were less likely to have traditional vascular risk factors than nonsmokers. Smokers had lower observed in‐hospital mortality compared with nonsmokers (2.0% versus 5.9%; unadjusted odds ratio 0.32, 95% CI 0.31–0.33, P<0.001). Although the association between smoking and lower in‐hospital mortality was partly attenuated after baseline risk adjustment, a significant residual association remained (adjusted odds ratio 0.60, 95% CI 0.58–0.62, P<0.001). This association largely persisted in age‐stratified analyses. Smoking status was also associated with shorter average length of stay (3.5 versus 4.5 days, P<0.001) and lower incidence of postprocedure hemorrhage (4.2% versus 6.1%; adjusted odds ratio 0.81, 95% CI 0.80–0.83, P<0.001) and in‐hospital cardiac arrest (1.3% versus 2.1%; adjusted OR 0.78, 95% CI 0.76–0.81, P<0.001).ConclusionsIn this nationwide cohort of patients undergoing primary percutaneous coronary intervention for ST‐segment elevation myocardial infarction, we observed significantly lower risk‐adjusted in‐hospital mortality in smokers, suggesting that the smoker's paradox also applies to ST‐segment elevation myocardial infarction patients undergoing primary percutaneous coronary intervention.

Incidence and Prognostic Impact of Respiratory Support in Patients With ST-Segment Elevation Myocardial Infarction

“…Of note, our findings of decreased likelihood of mortality associated with obesity and smoking are consistent with some other studies of the “obesity paradox” 15 and “smoker’s paradox” 16 , felt to represent asymmetry of baseline risk factors rather than protective effect. This paradox has been observed in other studies of STEMI in the NIS 17 . Our finding that weekend admission was associated with increased rates of respiratory failure may be related to the fact that multiple studies and a systematic review have suggested that STEMI patients admitted during weekends and off-hours have worse outcomes related in part to delays in presentation and longer door-to-reperfusion times 18 .…”

Prognostic Factors in Patients With Stemi Undergoing Primary PCI in the Clopidogrel Era: Role of Dual Antiplatelet Therapy at Admission and the Smoking Paradox on Long‐Term Outcome

“…This effect was even more pronounced in high‐risk patients, especially those with ACS; this has been defined as “the smoking paradox.” The reasons for this paradoxical effect of smoking are not completely known, but could be related to an induction of CYP1A2 by cigarette smoking, which would lead to an increased production of the active metabolite of clopidogrel . However, the interaction of smoking in patients with ACS remains controversial, with recent studies having questioned the role of smoking as a positive prognostic factor in ACS patients, while others have shown that smokers on clopidogrel have a better outcome than non smokers on clopidogrel …”

Double‐Dose Versus Standard‐Dose Clopidogrel According to Smoking Status Among Patients With Acute Coronary Syndromes Undergoing Percutaneous Coronary Intervention

“…Earlier studies have suggested better short-term outcomes among smokers with myocardial infarction (MI), a phenomenon known as the "smoker's paradox." [2][3][4][5][6] This may be because of the lower age and baseline risk profile in smokers compared with nonsmokers. However, recent studies have highlighted the detrimental influence of smoking on short-and longterm outcome in ACS patients, with a substantially higher risk for re-infarction, stent thrombosis, and death in smokers, irrespective of age.…”