Abstract
Smoking is an established risk factor for cardiovascular disease including coronary heart disease and stroke, however, data regarding smoking and sudden cardiac death have not been summarized in a meta-analysis previously. We therefore conducted a systematic review and meta-analysis to clarify this association. We searched the PubMed and Embase databases for studies of smoking and sudden cardiac death up to July 20th 2017. Prospective studies were included if they reported adjusted relative risk (RR) estimates and 95% confidence intervals (CIs) for smoking and sudden cardiac death. Summary RRs were estimated by use of a random effects model. Twelve prospective studies were included. The summary RR was 3.06 (95% CI 2.46–3.82, I2 = 41%, pheterogeneity = 0.12, n = 7) for current smokers and 1.38 (95% CI 1.20–1.60, I2 = 0%, pheterogeneity = 0.55, n = 7) for former smokers compared to never smokers. For four studies using non-current (never + former) smokers as the reference category the summary RR among current smokers was 2.08 (95% CI 1.70–2.53, I2 = 18%, pheterogeneity = 0.30). The results persisted in most of the subgroup analyses. There was no evidence of publication bias. These results confirm that smoking increases the risk of sudden cardiac death. Any further studies should investigate in more detail the effects of duration of smoking, number of cigarettes per day, pack-years, and time since quitting smoking and sudden cardiac death.
Highlights
Smoking is an established risk factor for cardiovascular disease including coronary heart disease and stroke, data regarding smoking and sudden cardiac death have not been summarized in a meta-analysis previously
The summary relative risk (RR) was 3.06 for current smokers and 1.38 for former smokers compared to never smokers
Preventive efforts have focused on using cardioverter-defibrillators in the highest risk groups such as patients with advanced cardiomyopathy and reduced left ventricular ejection fraction [8], these high risk groups only account for 25–30% of all sudden cardiac deaths and the majority occur in the general population and in persons without established coronary heart disease [9, 10]
Summary
Cardiovascular disease is the leading cause of death globally, accounting for 17.9 million deaths worldwide in 2015 [1]. In the US approximately 250 000–310 000 sudden cardiac deaths occur annually [3, 4]. Preventive efforts have focused on using cardioverter-defibrillators in the highest risk groups such as patients with advanced cardiomyopathy and reduced left ventricular ejection fraction [8], these high risk groups only account for 25–30% of all sudden cardiac deaths and the majority occur in the general population and in persons without established coronary heart disease [9, 10]. Population-wide strategies for primary prevention may be a more promising approach to reduce the incidence of sudden cardiac deaths
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