Metabolic syndrome and the risk of sudden cardiac death in middle-aged men

Background Little is known about the relationship between metabolic syndrome and sudden cardiac death (SCD). We examined the association of metabolic syndrome, as defined by World Health Organization (WHO), International Diabetes Federation (IDF), National Cholesterol Education Program (NCEP) and American Heart Association (AHA) - IDF interim criteria, with incident SCD. We also assessed the association of a continuous metabolic risk score with SCD. Methods A total of 1466 middle-aged men participating in a prospective population-based cohort study from eastern Finland with no history of coronary heart disease or diabetes at baseline were included. Results During the average follow-up of 21 years 85 SCDs occurred. Men with the metabolic syndrome as defined by the WHO, NCEP, IDF and interim criteria had a 2.2-2.6 fold, increased risk for SCD, after adjusting for lifestyle and traditional cardiovascular risk factors not included in the metabolic syndrome definition (P < 0.001-0.011). A one-standard deviation increase in the metabolic risk score (composed of the sum of Z-scores for waist circumference, insulin, glucose, high-density lipoprotein (HDL) cholesterol, triglycerides, and blood pressure) was associated with a 1.68-fold higher (95% CI 1.33-2.11) risk of SCD. Even when adjusting further for systolic blood pressure, HDL cholesterol and body mass index, the association remained significant for the interim criteria and the metabolic risk score, but not for WHO, NCEP, or IDF definitions. Conclusions Men with metabolic syndrome are at increased risk for SCD. Incident SCD associated with the IDF/AHA interim criteria and metabolic risk clustering estimated by a score is not explained by obesity or traditional cardiovascular risk factors. Key messages Men with metabolic syndrome are at increased risk for sudden cardiac death. Incident sudden cardiac death associated with metabolic risk clustering estimated by a score in not explained by obesity or traditional cardiovascular risk factors. Prevention of the metabolic syndrome may help reduce the health burden of SCD.