The way endurance athletes are commonly tested for potentially deadly heart arrhythmias doesn't actually work, finds new research. Doctors routinely check athletes for abnormal heart rhythms by assessing their left ventricle while they are at rest. But dangerous arrhythmias can occur in the right ventricle, and these findings prove that they can only be detected during intense exercise.
Arrhythmias, which are any irregularity in the heart's electrical system, are actually fairly common among athletes. A vast majority of the time they're not life-threatening, says Dr. Aaron Baggish, associate director of the Cardiovascular Performance Program at Massachusetts General Hospital. However, for a small percentage of marathoners, triathletes, cyclists, and other endurance athletes, an arrhythmia can cause their heartbeat to suddenly speed up or slow down, and they can die on the spot.
For this study, a team of Australian and Belgian researchers recruited 17 endurance athletes with right-ventricle arrhythmias, 10 athletes with normal hearts, and seven non-athletes. They tested all of the participants' heart function while resting and their left ventricles during exercise. Everyone's hearts — even those with known arrhythmias — appeared normal. Only while the participants were working out could the researchers spot the arrhythmias in those athletes' right ventricles.
This makes perfect sense, says Baggish. "You can't tell as much about an athlete's physiology when he is at rest," he explains. "It's just like how you don't evaluate a racecar while it's sitting in the garage — you test it out on the track when it's moving. In order to detect these serious arrhythmias, you have to put athletes through very rigorous sport-specific paces to really evaluate their hearts." Baggish says some doctors are already testing athletes for arrhythmias the proper way, and he hopes this study will make right-side testing while exercising the norm.
Regardless, Baggish insists that runners — whether casual joggers or hardcore marathoners — shouldn't lose sleep over a possible problematic arrhythmia unless you're having symptoms like fainting, unusual shortness of breath, or performance declines. "Healthy athletes who feel healthy typically are," he says. "Even most asymptomatic arrhythmias detected by a doctor doing routine testing are usually benign." But if you start to develop symptoms of arrhythmia at any point, however, you should definitely see your doctor immediately.