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Adults whose resting heart rate follows an atypical pattern as they age may face a greater risk for developing heart failure or dying from any cause than people whose heart rates follow a normal trajectory, new research suggests.

People whose heart rates consistently increased over more than two decades – whether slightly or substantially – were more likely to die or develop heart failure than those whose resting heart rate remained stable or declined slightly, researchers found.

The were presented earlier this month at the 91ÊÓƵ's Scientific Sessions in Chicago. They are considered preliminary until full results are published in a peer-reviewed journal.

The study's senior researcher Dr. Kunihiro Matsushita, a professor at both Johns Hopkins School of Medicine and its Bloomberg School of Public Health in Baltimore, said he was surprised to see nearly 90% of study participants followed a stable or slightly declining heart rate trajectory.

"I expected more variation, to be honest," he said. "The findings tell me that resting heart rate is well controlled in most people. But we found more than 10% of people don't follow that pattern."

The study raises questions about what's causing the atypical patterns and how they may contribute to poor cardiovascular health, said lead researcher Ning Meng, a research associate in the division of rheumatology at Johns Hopkins School of Medicine. "Now we can dig deeper to find the mechanisms."

Heart rate, also referred to as a pulse, refers to the number of times a heart beats each minute. Heart rate rises during exercise or exertion. Resting heart rate refers to the number of heartbeats when a person is at rest. For most adults, a normal resting heart rate falls between 60 and 100 beats per minute. People who are more physically fit tend to have lower resting heart rates than those who are not.

Researchers analyzed health data for 5,794 participants in the Atherosclerosis Risk in Communities, or ARIC, study to identify resting heart rate patterns over 25 years and found four trajectories. More than 88% of participants exhibited a pattern of stable or slightly declining resting heart rates over the study period, with the remainder falling into three atypical patterns.

Roughly 9% experienced a stable then slightly increasing heart rate with age, 2% had heart rates that rose and fell, and about half a percentage point experienced a stable then sharply increasing resting heart rate. Participants were an average 52 years old at their first heart rate measurement and an average 76 years old at their last measurement.

People who smoked, had a history of heart failure, obesity or lower education levels were more likely to experience atypical patterns. After accounting for known cardiovascular risk factors, people whose resting heart rate increased slightly or sharply were 65% more likely to develop heart failure than those whose resting heart rate decreased slightly over the study period, and 69% more likely to die from any cause.

"As a population, humans are measuring heart rate more and more, as this is easily done with wearable devices," said Dr. Meagan Wasfy, a cardiologist at Massachusetts General Hospital and an assistant professor at Harvard Medical School in Boston. "We have humans looking at their heart rate every morning when they wake up. This study tells us what changes in heart rate mean over time.

"Knowing what good versus bad trajectories look like could help us to identify those at risk for poor outcomes, who warrant closer attention or an intervention," said Wasfy, who was not involved in the research.

Matsushita said whether heart rate can or should be targeted for treatment has yet to be established. "The next step is to find what causes these atypical patterns. Why do changes occur and why do they confer an elevated risk of cardiovascular disease?"

In the meantime, Wasfy said, "the take-home message is that if you notice changes in your resting heart rate, especially if you have other symptoms, talk to your doctor."

Find more news from Scientific Sessions.