Sudden cardiac death (SCD) in obesity is the focus of a JACC: State-of-the-Art review of the mechanisms as well as current evidence for its management, gaps in knowledge and future research, published in JACC.

Lauri Holmstrom, MD, PhD, et al., write that obesity-related SCD is “an increasingly important public health problem and warrants a specific investigative focus on improved risk stratification and prevention.”

Specifically, the authors summarize epidemiological evidence linking obesity to SCD, noting that increased body mass index (BMI) and particularly visceral obesity increase the risk of SCD. One meta-analysis showed a 16% increase in SCD risk with every 5-unit increment in BMI.

In looking at clinical antecedents of obesity-related SCD, they review research suggesting obesity is a risk factor for SCD independent of conventional risk factors and that accelerated development of coronary artery disease and myocardial infarction do not fully explain the risk.

Clinical characteristics of SCD in obesity from autopsy are also summarized, including prevalence, diurnal variation and presenting rhythm as well as electrocardiographic abnormalities. “Current evidence indicates that the most common autopsy findings among obese SCD cases are cardiac hypertrophy and coronary artery disease when all age groups are included,” the authors note.

Regarding potential mechanisms of lethal arrhythmias, the authors review research on the impact of electrical remodeling and structural remodeling of the heart associated with obesity in leading to SCD, as well as a fatty heart.

In terms of risk stratification and prevention, while this is currently based on assessment of left ventricular ejection fraction and implanting an ICD for high-risk patients, they write this should be revisited. For example, they note that advanced in heart failure (HF) management has led to about a 44% decline in the rate of SCD in HF with a concomitant reduction in ICD therapy events. “Accurate SCD risk stratification in obesity is likely to require a combination of various biomarkers,” they write, including, for example, metabolic alterations, -omics, data, cardiovascular imaging, and ECG, along with more sophisticated measurement of body composition and fat distribution.

Among areas for future research to address knowledge gaps are mediators for SCD risk in obesity to improve long-term prediction and prevention as well as identify potential therapeutic targets; emerging metrics of body composition; and the effect of novel obesity therapies, such as GLP-1 RAs, on SCD burden, along with bariatric surgery.

Looking ahead, the impact of obesity on SCD across socioeconomic status and racial/ethnic groups also require further investigation. ”Socioeconomic disadvantages and variable access to preventive health care may have an important effect on the risk of obesity and SCD,” write the authors. Targeted community-specific education and preventive health care have the potential to improve early diagnosis and SCD prevention.

Clinical Topics: Arrhythmias and Clinical EP, Diabetes and Cardiometabolic Disease, Heart Failure and Cardiomyopathies, SCD/Ventricular Arrhythmias, Acute Heart Failure

Keywords: Body Mass Index, Obesity, Abdominal, Death, Sudden, Cardiac, Heart Failure, Bariatric Surgery