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• Posted July 26, 2024

Tough Workouts Won't Trigger Cardiac Arrest in Folks With Long QT Syndrome

People diagnosed with one of the most common inherited heart arrhythmias, called Long QT syndrome (LQTS), can safely engage in vigorous exercise without any added risk for sudden death or cardiac arrest, a new study finds.

"Arrhythmic events were low in these appropriately treated individuals with LQTS in both those exercising vigorously and those exercising moderately or who were sedentary," concluded a team led by Dr. Rachel Lampert, a professor of cardiology at Yale University School of Medicine.

According to the Cleveland Clinic, LQTS involves delays in "recharging" the heart's electrical system, which in turn can lead to a potentially dangerous irregular heartbeat.

Medications, implanted devices and surgery are used to help control the condition, which is often inherited.

According to one European study, LQTS occurs in about 1 in every 2,500 people, making it "the most commonly detected genetic electrical abnormality" of the heart, Lampert's team said.

Prior studies had suggested that vigorous exercise might help trigger cardiac arrest in people with LQTS, but as the researchers pointed out, those studies largely involved patients whose LQTS was only diagnosed after such a heart event.

What about people who already know they have LQTS and are being appropriately treated?

To find out, her team tracked outcomes over three years for 1,413 people diagnosed with LQTS at 37 medical sites in five countries.

These people ranged in age from 8 to 60 and had found out they carried the gene that causes LQTS, or they had had their condition spotted on an EKG.

At the time of the study, everyone was getting either medications and/or an implanted device (such as a defibrillator) to help treat the condition.

More than half (52%) of the study participants were vigorous exercisers -- for example, runners. The others either exercised either moderately (this included activities such as walking or yard work) or they were largely sedentary.

The bottom line: Over the three years of the study, there was no statistically significant difference between the groups in the occurrence of four cardiac issues: Sudden death, nonfatal sudden cardiac arrest, fainting caused by irregular heartbeat or arrhythmias deemed so difficult they needed treatment with an implanted defibrillator.

The overall rate of cardiac events was low -- 2.6% among those who engaged in vigorous exercise, and 2.7% for those who exercised less vigorously, the team said.

In fact, over the whole of the study only one participant experienced sudden cardiac death.

According to the researchers, this 31-year-old woman was later found to have had a second serious heart syndrome and she had also "purposefully deactivated" her treatment around the time of her death.

A total of 116 of the people in the study were "competitive athletes," and their level of cardiac events was also very low, the study authors noted.

They believe that, properly treated, LQTS should be no barrier to exercise, even when workouts become intense.

Decisions around whether these patients should engage in sports or tough workouts should perhaps no longer be made by doctors alone, Lampert's team added, but through "shared decision-making" between patient and doctor as to whether these activities are warranted.

The findings were published July 25 in the journal Circulation.

More information

Find out more about how Long QT syndrome is diagnosed and treated at the Mayo Clinic.

SOURCE: Circulation, July 25, 2024