Purpose: To examine the effect of age, body mass index (BMI) and blood pressure on cardiomegaly-related cardiac deaths in US firefighters.
Methods: In this retrospective case-control study, 98 on-duty SCD cases with cardiomegaly (at autopsy) and with medical information available from the US National Institute for Occupational Safety and Health Fire Fighter Fatality Investigation and Prevention Program were compared with 305 occupationally active firefighter controls who were free of left ventricular hypertrophy (LVH). Cardiomegaly was defined as heart weight greater than 450 grams in cases and LVH was defined as LV mass index greater than 81 g/m1.7 based on echocardiographic imaging in controls. BMI and blood pressure from medical records were used to define obesity and hypertension. Chi-square analyses were used for the comparison of categorical variables. Binary logistic regression was performed to calculate the odds ratios of cardiomegaly–related SCD for age, BMI and systolic blood pressure. A 0.05 level of significance was used for all tests.
Results: Of the cardiomegaly-associated SCD cases, 72% were obeseand 62% were hypertensive versus 53% and 11% of controls (p=0.001 and p<0.001, respectively). In multivariate analysis, increasing body mass index conveyed a 1.11 fold (95% confidence interval (CI) 1.05-1.17, p<0.001) and systolic blood pressure conveyed a 1.05 fold (95% CI 1.03-1.07, p<0.001) increased risk of cardiomegaly-related SCD when treated as continuous variables.
Conclusion(s): Using autopsy data and medical records,we found that BMI and systolic blood pressure were independent predictors of on-duty cardiomegaly-associated SCD in US firefighters. Each unit increase in BMI was associated with an 11% increased risk and each millimeter increase in systolic blood pressure was associated with a 5% increased risk. Our results indicate that cardiomegaly-related SCD is associated with modifiable cardiovascular disease risk factors. Taken together with the high prevalence of cardiomegaly in the US fire service, our results indicate that screening for cardiomegaly and targeted interventions for reducing obesity and aggressively managing blood pressure could reduce the risk of on-duty SCD among US firefighters.