High BMI in male teens tied to early AF with worse outcomes

Adolescent boys with high body mass index (BMI) are highly likely to develop early-onset atrial fibrillation (AF) with subsequently worse clinical outcomes, including all-cause mortality, heart failure, and stroke, according to a study.

The register‐based cohort study involved 1,704,467 men (mean age 18.3 years) who were enrolled in compulsory military service in Sweden. Baseline measurements included height and weight, blood pressure, fitness, muscle strength, intelligence quotient, and medical disorders.

Researchers determined the incidence and clinical outcomes of AF using records obtained from the National Inpatient Registry and the Cause of Death Register.

Of the men, 8.1 percent were underweight (BMI <18.5 kg/m²), 79.5 percent were normal weight (BMI 18.5 to <25 kg/m²), 10.0 percent were overweight (BMI 25 to <30 kg/m²), 1.8 percent were obese, 0.4 percent were severely obese, and 0.1 percent were morbidly obese.

Over a median follow‐up of 32 years, 36,693 men developed AF. The number of AF cases in the total cohort was 68 per 100,000 observed person‐years, increasing from 61 per 100,000 person‐years among those with BMI of 18.5 to <20 kg/m² to 131 per 100,000 person‐years among those with BMI of 40–50 kg/m². The median age of AF diagnosis in the total cohort was 52.4 years, decreasing from a median of 54 years among those with BMI of 18.5 kg/m² to 43.4 years among those with BMI of 40–50 kg/m².

Compared with men with BMI of 18.5 to <20.0 kg/m², those with BMI of 40.0 to 50.0 kg/m² had the highest risk of AF (hazard ratio [HR], 3.72, 95 percent confidence interval [CI], 2.44–5.66) followed by those with BMI of 20.0 to <22.5 kg/m² (HR, 1.06, 95 percent CI, 1.03–1.10).

In the group of men who developed AF, a total of 3,767 deaths, 3,251 cases of incident heart failure, and 921 cases of ischaemic stroke occurred during a median follow‐up of ≈6 years. The multivariable‐adjusted HRs for all‐cause mortality, incident heart failure, and ischemic stroke in AF‐diagnosed men with baseline BMI >30 kg/m² vs those with BMI <20 kg/m² were 2.86 (95 percent CI, 2.30–3.56), 3.42 (95 percent CI, 2.50–4.68), and 2.34 (95 percent CI, 1.52–3.61), respectively.