Study reveals why women tend to have faster heartbeats, men more irregular rhythms

The research shows that the sinoatrial node (SAN) -- a small but powerful structure in the human heart that serves as its natural pacemaker and initiates every normal heartbeat -- runs on different gene blueprints in men and women. The study found that women have genes that help their hearts beat faster while men have gene networks that may lead to heart problems like AFib. The research was recently published in the American Heart Association's Circulation: Arrythmia and Electrophysiology.

"We found for the first time that the genes controlling how the SAN works are influenced by sex," said Vadim Fedorov, PhD, professor of physiology and cell biology, Corrine Frick Research Chair in Heart Failure and Arrhythmia at the Ohio State University College of Medicine and senior author of the study. "That helps explain why women generally have faster heart rates and are more likely to experience inappropriate sinus tachycardia, while men face a greater risk of heart rate disorders like conduction block and atrial fibrillation."

Researchers at Ohio State University's Dorothy M. Davis Heart and Lung Research Institute and Bob and Corrine Frick Center for Heart Failure and Arrhythmia examined donated human hearts to unmask unique gene sets in the SAN pacemaker cells responsible for the generation and maintenance of heart rates. They analyzed genes and pathways involved in pacing, metabolism, inflammation and fibrotic remodeling and discovered distinct patterns tied to biological sex. The hearts were donated for research by organ donor families through Lifeline of Ohio.

"Women showed higher levels of TBX3 and HCN1, which are two key genes that help drive faster heart rhythms," said Ning Li, MD, PhD, Ohio State research assistant professor and co-author of the study. "In contrast, male hearts had more activity in gene networks related to inflammation and collagen production, which can interfere with electrical signaling and increase the risk of arrhythmias."

The findings could help lay the groundwork for more personalized, patient-specific approaches to treating heart rhythm disorders, Fedorov said. The study builds on Ohio State's broader efforts to understand and prevent the most common cardiac arrhythmias that can lead to dangerously slow or fast heart rates and often require interventions such as medication or pacemaker implantation. According to the American Heart Association, more than 6 million Americans are currently living with heart failure and many also suffer from rhythm disturbances originating in the SAN.

This research was supported by the National Institutes of Health, the Leducq Foundation and the Bob and Corrine Frick Center for Heart Failure and Arrhythmia, the nation's first center dedicated to treating patients with both heart failure and arrhythmia.