A high resting heart rate (generally thought to be over 100 beats per minute) is associated with an increased risk of serious cardiovascular disease, such as coronary heart disease and stroke. While the causes of an excessively high resting heart rate (RHR) can fluctuate due to factors such as stress, anxiety, hormonal changes, and medications, for those with genetic variants that cause elevated readings, it may be more difficult to implement lifestyle interventions to keep them within a "normal" range.
Researchers at the Northwestern Medicine Institute studied 835,365 people in the UK Biobank and International Resting Heart Rate Consortium (IC-RHR) study dataset and conducted a genome-wide meta-analysis of 99 studies to identify 68 previously unknown genetic variants that contribute to naturally elevated RHR.
"This is the largest study of its kind to date," said study co-author Marilyn Cornelis, associate professor of preventive medicine at Northwestern University. "In addition to adding to the list of genes with variants associated with heart rate, this study provides a strong causal link between heart rate and cardiovascular health."
Dr. Marilyn Cornelis, associate professor of preventive medicine in the Division of Nutrition, is one of the co-authors of the study published in Nature Communications.
In total, the scientists found 493 genetic variants at 352 genetic sites, with cardiovascular tissue being the primary site of how the variants alter gene expression. The RHR gene is most highly expressed in ventricular and atrial cardiomyocytes, the striated muscle branch cells in the heart responsible for cardiac contraction.
Meta-analyses link genetically high RHR to a higher risk of dilated cardiomyopathy, in which enlarged heart chambers lose their ability to contract. It can cause blood clots, arrhythmias, and chronic heart failure.
However, studies have also shown an inverse relationship between high RHR and other cardiovascular diseases such as atrial fibrillation, ischemic stroke and myoembolic stroke.
The researchers also found no link between genetic variants and increased mortality. According to the American Heart Association, a "normal" RHR is 60-100 bpm, and anything above this increases the risk of cardiovascular disease.
The researchers added that understanding how genetic variants lead to elevated RHR and its impact will lead to more informed and more personalized medical intervention for patients. Developing therapies to counteract the effects of genetic variants remains an emerging field of medicine.
A paper on this research was published in the journal Nature Communications.