Men and women have different heart rhythms, and now we know why

The human heart, a powerful organ, functions as the body’s engine, tirelessly pumping blood to sustain life. However, the way it beats differs between men and women.

For decades, scientists have observed that women tend to have faster heartbeats, while men are more susceptible to irregular rhythms like atrial fibrillation (AFib). Despite the evident differences, the underlying reasons remained elusive – until now.

A new study from The Ohio State University Wexner Medical Center dives into this mystery. Researchers found that the sinoatrial node (SAN), the heart’s natural pacemaker, operates differently in men and women. It’s not just about hormones or body size. The difference is in the genes.

The heart’s pacemaker in women

Think of the SAN as the heart’s rhythm section. It sets the beat, making sure the heart pumps blood steadily. But the way it does that isn’t the same for everyone.

Ohio State researchers examined donated human hearts. They focused on the SAN cells, digging deep into their genetic blueprints. What they found surprised them. The genes running the SAN look different in men and women.

“We found for the first time that the genes controlling how the SAN works are influenced by sex,” said Dr. Vadim Fedorov, lead author and Corrine Frick Research Chair in Heart Failure and Arrhythmia.

“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.”

Genetic differences in heart rhythms

Researchers zoomed in on the genetic networks that keep the heart beating. In women, they spotted genes that push the heart to beat faster. TBX3 and HCN1 stood out. They’re the genes responsible for faster rhythms.

Meanwhile, men’s hearts told a different story. Genes linked to inflammation and collagen production dominated. These genes can mess with the heart’s electrical signals, increasing the risk of arrhythmias.

“Women showed higher levels of TBX3 and HCN1, which are two key genes that help drive faster heart rhythms,” said Dr. Ning Li, co-author and research assistant professor at Ohio State.

“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.”

Examining real human hearts

The researchers didn’t just rely on lab models. They examined actual human hearts, donated through Lifeline of Ohio. Each heart revealed a unique genetic signature, offering clues to how sex influences heart rhythm.

In the lab, the team analyzed genes involved in pacing, metabolism, inflammation, and fibrotic remodeling. They wanted to know how these genes affected SAN cells – the heart’s metronome.

Heart rhythm genes in women

Why do these genetic differences matter? Because they could explain why men and women often experience different heart rhythm problems.

Women’s hearts beat faster, making them more prone to inappropriate sinus tachycardia. Meanwhile, men face a higher risk of AFib, a condition where the heart’s rhythm goes haywire. The genes that drive these conditions may also hold the key to better, more targeted treatments.

Can genes guide heart treatments?

This study is part of Ohio State’s broader mission to prevent and treat heart rhythm disorders. Millions of Americans live with AFib or other arrhythmias. Most rely on medications or pacemakers to keep their hearts in sync.

But what if doctors could target those genetic networks instead? By understanding the gene patterns that influence SAN function, they might develop more effective treatments.

The findings open the door to personalized medicine – treatments based on genetic makeup rather than just symptoms. Imagine a world where doctors don’t just treat the heart. They treat the genes behind its rhythm.

Next steps in heart research

The study’s authors aren’t stopping here. Next, they plan to look at how age and lifestyle might influence those genetic networks. Will those genes shift over time? Will they react to diet, exercise, or stress?

Researchers hope to answer these questions in future studies. For now, they’ve taken a big step forward in understanding why men and women’s hearts beat to different tunes – and how that rhythm could one day save lives.

The National Institutes of Health, the Leducq Foundation, and the Bob and Corrine Frick Center for Heart Failure and Arrhythmia funded the study.

The Frick Center is the first in the nation to focus on treating both heart failure and arrhythmias, making it a fitting partner for this groundbreaking research.

The study is published in the journal Circulation Arrhythmia and Electrophysiology.

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