Former world-class rowers have an elevated risk for atrial fibrillation (AF) in the years after retirement, according to an observational case-control study.
Researchers found 1 in 5 former Olympic, world, or national-level Australian rowers aged 45-80 years had the heart rhythm anomaly. The ex-rowers, who had competed for at least 10 years, were nearly seven times more likely to have been diagnosed with AF compared to a control group. During a follow-up period of around 4 years, new cases of AF were also higher among the ex-rowers (6.3% vs 2.3%), according to the researchers, who published their findings last month in the European Heart Journal.
“As a clinician, I was not surprised that rowers experienced more AF,” said André La Gerche, PhD, MD, a cardiologist and head of the Heart Exercise And Research Trials Lab at the Victor Chang Cardiac Research Institute and St Vincent’s Hospital in Melbourne, Australia, and senior author of the study. “However, I was very surprised by the magnitude of the difference. Furthermore, I learnt that the risk persists years after retirement and is not just due to genetic factors.”
The findings are “consistent with prior research demonstrating that endurance athletes — especially highly trained endurance athletes — seem to have this higher risk of AF,” said Gregory Marcus, MD, MAS, a cardiac electrophysiologist and the inaugural Endowed Professor of Atrial Fibrillation Research at the University of California, San Francisco.
“These numbers nudge me in the direction of more aggressively screening for AF specifically in masters-aged rowers, such as with the use of Holter monitors or wearable devices approved to detect AF,” said Jeffrey Hsu, MD, an assistant professor of medicine in the Division of Cardiology at the David Geffen School of Medicine at the University of California, Los Angeles.
La Gerche and his team captured data from 121 former rowers — 75% men, all White, with a median age of 62 years — who were matched with more than 11,000 control individuals from the UK Biobank who had never rowed and had varying fitness levels. The ex-rowers had similar rates of ischemic heart disease and diabetes as did the control individuals, but lower blood pressure. They also were less likely to have ever smoked.
The athletes showed persistent changes in cardiac function after retirement. Ex-rowers had larger left ventricles, lower heart rates, longer PQ intervals, and longer QT intervals compared to control individuals.
The research, “raises the question of whether certain types of intensive exercise — like elite-level competitive rowing — leads to long-lasting, perhaps even irreversible, enlargement of the cardiac chambers,” Hsu said.
Genetics factored into the risk for AF among both groups. While the prevalence of rare variants in genes associated with cardiomyopathy was low across the study, the combined risk for individual genes associated with AF was a strong predictor of the disease in both athletes (odds ratio [OR], 3.7) and nonathletes (OR, 2.0). The proportions were similar between them (P = .37), indicating genetics did not fully account for the increased risk in the ex-rowers, La Gerche said.
Marcus flagged a few factors that may have skewed the results. The former athletes tended to be tall, White, and in many cases, drank more alcohol than control individuals — all of these factors increase the risk for AF.
Because the ex-rowers volunteered for a cardiovascular study, selection bias could have skewed prevalence higher, Marcus said. After a sensitivity analysis, ex-rowers still had a 2.5-fold higher risk for AF in the case of a 100% selection bias.
La Gerche emphasized the findings shouldn’t dissuade clinicians from encouraging regular exercise or high-level sports training.
“The overall health outcomes of these rowers are generally superb,” La Gerche said. “Rather, this highlights an important ‘Achilles heel’ that requires attention and, ideally, effective prevention strategies so that sports can be enjoyed by more people, more often.”
The study was funded by the National Health and Medical Research Council. La Gerche, Hsu, and Marcus reported having no relevant financial conflicts of interest.
Brittany Vargas is a journalist covering medicine, mental health, and wellness.