A high resting heart rate, which is generally considered anything above 100 beats per minute (bpm), has been linked to an elevated risk of serious cardiovascular conditions such coronary artery disease and stroke. And while the cause of a high resting heart rate (RHR) can fluctuate, due to factors such as stress, anxiety, hormonal changes and medication, lifestyle interventions to get it within a 'normal' range can be more difficult for those with genetic variants contributing to the elevated readings.
Looking at a genome-wide meta-analysis of 99 studies, covering 835,365 individuals from the UK Biobank and the International Consortium of Resting Heart Rate (IC-RHR) study datasets, Northwestern Medicine researchers have identified 68 previously unknown genetic variants that contribute to naturally higher RHR.
“This is the largest study of its kind to-date," said study co-author Marilyn Cornelis, associate professor of Preventive Medicine at Northwestern. "Besides adding to the list of variants linked to heart rate, the research provides robust causal relationships between heart rate and cardiovascular health."
Overall, the scientists found 493 genetic variants in 352 loci, with cardiovascular tissues being the main site for how variants altered gene expression. RHR gene expression was highest in ventricular and atrial cardiomyocytes, the striated branched muscle cells in the heart that are responsible for the contractions of the heart.
The meta-analysis linked genetic high RHR with a higher risk of dilated cardiomyopathy, in which enlarged heart chambers lose the ability to contract. It can lead to blood clots, arrhythmia and chronic heart failure.
However, the study also showed an inverse relationship between high RHR and other cardiovascular conditions such as atrial fibrillation, ischemic stroke and cardio-embolic stroke.
The researchers also found no link between the genetic variants and increased mortality.
According to the American Heart Association, a ‘normal’ RHR is 60-100 bpm, with anything above this increasing risk of cardiovascular disease.
Understanding how genetic variants contribute to elevated RHR and their implications will help patients receive more informed and personalized healthcare interventions, the researchers added. Developing therapeutics to combat the influence of genetic variations is still an emerging field of medicine.
The study was published in the journal Nature Communications.
Source: Northwestern Medicine