Both general and central obesity are associated with an increased risk of sudden cardiac death in middle-aged men and women, a prospective cohort study has found.

Data from 14,941 men and women aged 45-64 (mean 54) years, taking part in the Atherosclerosis Risk in Communities (ARIC) study were analysed. The participants who were African American or white were recruited from four centres in the US. Body mass index (BMI), waist circumference and waist:hip ratio were measured at baseline. Mean follow-up was 12.6 years.

There were 253 sudden cardiac deaths, incidence rate 1.34/1,000 person-years. After adjusting for age, sex, race, study centre and education level, sudden cardiac death risk was continuously and positively associated (P < 0.001) with BMI, waist circumference and waist:hip ratio in nonsmokers, but not in smokers. Waist:hip ratio was more strongly associated with sudden cardiac death in nonsmokers than BMI or waist circumference.

After adjustment for hypertension, diabetes, lipid profile, prevalent coronary heart disease, heart failure, and LV hypertrophy, nonsmokers in the highest waist:hip ratio category had double the risk of sudden cardiac death HR 2.03 (95% CI:1.19-3.46); incidence rate 1.43/1,000 person-years compared with those with normal waist:hip ratio.

Obesity is a major health problem and a recognised risk factor for a broad range of cardiovascular, metabolic, neoplastic and musculoskeletal disorders. It is thought to reduce life expectancy by ten years in people with a BMI > 40 kg/m2 i.e. those with  morbid obesity.

Obesity has adverse structural and electrical effects on the heart and as such potentially creates a substrate for sudden cardiac death.

The authors concluded that general obesity is associated with increased risk of sudden cardiac death in

middle-aged, nonsmoking individuals, mediated by traditional cardiovascular risk factors such as high blood pressure, lipid profile, diabetes and CHD. Central obesity, however, is independently associated with sudden cardiac death by pathways that are at present unknown.

Dr Peter Savill

• Adabag S, Huxley RR, Lopez FL et al. Obesity related risk of sudden cardiac death in the atherosclerosis risk in communities study. Heart 2015;101:215-221 doi:10.1136/heartjnl-2014-306238