Abstract Body (Do not enter title and authors here): Background: Studies have reported association between obesity and sudden cardiac death (SCD) but presume cardiac cause without autopsy. Elucidating causes of SCD by weight status may refine prevention strategies.
Question: What are the autopsy causes of community sudden death by weight status?
Methods: The POstmortem Systematic InvesTigation of SCD (POST SCD) is an ongoing prospective study using autopsy and clinical records to adjudicate arrhythmic (potentially rescuable with ICD) vs. non-arrhythmic (tamponade, stroke) causes among presumed SCDs (pSCDs) meeting WHO criteria in San Francisco County since 2011. Body mass index (BMI) was categorized as underweight (UW; <18.5), healthy (18.5-24.9), overweight (OW; 25-29.9), or obese (OB; >30).
Results: Of 1,115 total pSCDs from 2/1/2011-1/1/2024, 322 (29%) were healthy by BMI, 51 (5%) UW, 344 (31%) OW, and 398 (36%) OB. Compared to healthy BMI, OB victims were younger (mean 56 vs 60 years, p<.001), less likely Asian (11% vs 25%, p<.001), more likely Black (23% vs 16%, p<.03), and had more co-morbidities, including hypertension (55% vs 38%, p<.001), diabetes (28% vs 14%, p<.001), dyslipidemia (30% vs 16%, p<.001), diagnosed coronary artery disease (CAD; 15% vs 9%, p<.01), and chronic kidney disease (11% vs 4%, p<.01). UW pSCDs had similar demographics and co-morbidities as healthy BMI cases. The proportion of pSCDs attributable to arrhythmic causes increased with higher BMI: 27% (UW) to 49% (Healthy) to 58% (OW) to 60% (OB), p<.001. Compared to healthy, OB had more CAD (37% vs 26%, p<.01), cardiac hypertrophy (11% vs 6%, p<.05), and pulmonary embolism (7% vs 2%, p<.01) causes of pSCD. UW BMI victims had more non-cardiac causes (67% vs 49%, p<.01), including infection (16% vs 5%, p<.01) and respiratory failure (10% vs <1%, p<.001). Among arrhythmic deaths, OB cases had fewer normal heart/primary electrical disease causes vs healthy (3% vs 10%, p<.01), but other causes were similar across BMI classes.
Conclusions: In this 13-year countywide postmortem study, OB and OW sudden deaths had higher likelihood of arrhythmic causes while UW had more non-cardiac causes than pSCDs with healthy BMI. Among arrhythmic deaths, causes were similar by weight status, but OB victims had more cardiac pathology and pre-existing comorbidities. Awareness of non-cardiac causes in UW and redoubled efforts to screen and treat cardiac risk factors in OB individuals may mitigate sudden death risk at each end of the weight spectrum.