a new case-control study suggests.
Researchers who analyzed hearts taken at autopsy from people who had died from sudden cardiac death found that a number of the hearts obtained from obese decedents were heavier than those from normal-weight decedents and that the hazard ratio of unexplained cardiomegaly in this cohort was 5.3, compared with normal-weight individuals.
“Even when we ruled out any conditions that could potentially cause enlargement of the heart, including hypertension, heart valve problems, diabetes, and other cardiovascular risk factors, the association with obesity cardiomyopathy, or OCM, and sudden cardiac death remained,” lead author Joseph Westaby, PhD, from the Cardiac Risk in the Young (CRY) Cardiovascular Pathology Laboratories at St George’s University of London, said in an interview.
The study was published online in JACC: Advances.
Intrigued by this finding, Dr. Westaby and associates sought to characterize the clinical and pathological features of OCM associated with sudden cardiac death by comparing this population to two control groups: sudden cardiac death patients who were either obese or of normal weight, and had morphologically normal hearts.
Their group is uniquely positioned to do such research, Dr. Westaby explained.
“Here at St George’s University of London, we have a specialized cardiovascular pathology service. ... All hearts obtained at autopsy from individuals who have died from sudden cardiac death, or who were suspected to have had a cardiovascular cause of death, anywhere in the U.K., are referred to the CRY Centre for further analysis,” he said.
Patients were divided into two groups according to body mass index: an obesity group (BMI > 30 kg/m2) and a normal-weight group (BMI, 18.5-24.9).
An increased heart weight above 550 g in men and 450 g in women in the absence of coronary artery disease, hypertension, diabetes, or valvular disease was classified as unexplained cardiomegaly, and individuals with obesity and cardiomegaly were defined as obesity cardiomyopathy.
Age- and sex-matched controls with obesity (n = 106) were selected based on a BMI greater than 30, with a morphologically normal heart weighing less than 550 g in men and than 450 g in women.
Age- and sex-matched normal weight controls (n = 106) were selected based on a BMI of 18.5-24.9 and a morphologically normal heart weighing less than 550 g in men and less than 450 g in women.
The researchers identified 53 OCM cases from a cohort of more than 4,500 sudden cardiac death cases that had BMI measurements. In normal-weight patients, there were 14 cases of unexplained cardiomegaly.
The mean age at death of individuals with OCM was 42 years (range, 30-54 years). Most of the deaths occurred in men (n = 34; 64%), who also died younger than women (40 ± 13 years vs. 45 ± 10 years; P = .036).
The average heart weight in OCM patients was 598 ± 93 g. Risk of sudden cardiac death increased when BMI reached 35.
Compared with matched controls, there were increases in right and left ventricular wall thickness (all P < .05) in OCM cases. Right ventricular epicardial fat was increased in OCM cases, compared with normal-weight controls only.
Left ventricular fibrosis was identified in seven (13%) OCM cases.