Smoking and sudden cardiac death in patients with previous coronary artery disease.

Background: Smoking is a known risk for sudden cardiac death (SCD) in the general population. However, its significance in patients with acute coronary syndrome (ACS), a condition that also elevates the risk of SCD, is disputable.

Methods: A total of 9704 consecutive ACS patients with available smoking data were included in the analysis. Comprehensive patient data were obtained from the Mass Data in Detection and Prevention of Serious Adverse Events in Cardiovascular Disease research database. A composite endpoint of SCD, SCD aborted by successful resuscitation and accurate implantable cardioverter defibrillator therapy to otherwise potentially fatal ventricular fibrillation/ventricular tachycardia was used. Univariate, age- and sex-adjusted, and a multivariate fine-gray competing risk regression with adjustment to traditional risk factors was conducted.

Results: Median follow-up time was 6.8 years (IQR, 4.1-10.2), and 454 (4.7%) SCD cases were identified. At the baseline, 23.7% (N = 2444) were active smokers, and 20.8% (N = 2146) were ex-smokers. In the multivariate model, active smokers had an elevated risk of 1.79 (95% CI, 1.41-2.27; P < 0.001) for future SCD. Ex-smokers had no elevated risk for SCD in fine-gray subdistribution hazard. Also, active smokers were notably younger (mean age 58.7 years) than non- or ex-smokers (71.1 years and 68.9 years, respectively, P < 0.001 for both comparisons).

Conclusion: Active smokers had a 79% higher risk of SCD when compared with nonsmokers. Smoking cessation should be heavily encouraged after ACS. Also, a person's smoking status should be considered in further studies developing SCD and implantable cardioverter defibrillator-benefit risk scores.