Unexplained Drop in Resting Heart Rate in Youth 'Not a Good Thing'

MONDAY, April 19, 2021 (HealthDay News) -- Children who have a sudden lowering of their resting heart rate as they move into young adulthood may be at increased risk for heart disease later in life, researchers report.

For their new study, they assessed data from 759 Black and white participants in the Augusta Heart Study, which was designed to evaluate the development of risk factors for heart disease. It followed young participants in the Augusta, Ga. area, who were healthy and aged 5-16 at the time of enrollment, as they grew into adulthood.

Over 21 years, the resting heart rate of the participants was checked a minimum of three times. More than half had their heart rate checked eight times or more, up to a maximum of 15 times.

The researchers found that 30% of the participants started with a low resting heart rate, which decreased relatively rapidly as they moved into young adulthood; 45.6% started with a moderate resting heart rate and had a moderate decrease; and just over 24% started with a high resting heart rate and had a low decrease.

Heart rate decreases were 24.1, 19.1 and 17.4 beats per minute, respectively.

Further investigation revealed a significant association between a faster decrease in resting heart rate from childhood to adulthood and a larger left ventricle, the heart's major pumping chamber.

A faster decrease in heart rate also was associated with a higher level of pressure inside the blood vessels of the body, which the heart has to pump against to distribute blood and oxygen throughout the body.

These associations were generally stronger in Black participants, according to the Medical College of Georgia at Augusta University study, published recently in the journal Acta Cardiologica.

"An unexplained drop over time is not a good thing," study author Dr. Gaston Kapuku, a cardiovascular researcher at MCG's Georgia Prevention Institute, said in a college news release.

In response to continually pumping against higher blood pressure, the left ventricle gets larger but grows weaker, which can eventually lead to heart failure, the researchers explained.

So, unless a significant decrease in heart rate is due to intense aerobic activity, it likely indicates that person is at increased risk for heart disease and may benefit from medications, a pacemaker or exercise to normalize the rate, according to the study authors.

More information

The Heart Rhythm Society has more on a slow heartbeat.

SOURCE: Medical College of Georgia, news release, April 14, 2021