London, June 3 (IANS): The best way to save endurance athletes from a fatal heart condition is to test them during exercise and not when the heart is resting, new research says.

Some athletes, who take part in endurance exercise such as marathon running can develop irregularities in their heartbeats that can, occasionally, lead to sudden death.

New evidence has shown that doctors try to detect heartbeat irregularities (known as arrhythmias) while an athlete is resting. They miss important signs of right ventricular dysfunction that can only be detected during exercise and that could be fatal.

The findings have important clinical implications because, at present, routine assessments of athletes with suspected arrhythmias often involve looking at the heart while it is resting, with a focus on the left ventricle.

Previous research by professors Hein Heidbuchel and Andre La Gerche had already demonstrated that the thin-walled right ventricle of the heart, which pumps blood through the lungs, is subjected to much greater stresses during exertion than the left ventricle.

Prolonged exercise is associated with temporary damage to the right ventricle. In this new study, professor Andre La Gerche from Baker IDI Heart and Diabetes Institute, Melbourne and his colleagues found that problems in the way the right ventricle works become apparent only during exercise and cannot be detected when an athlete is resting.

"You do not test a racing car while it is sitting in the garage. Similarly, you cannot assess an athlete's heart until you assess it under the stress of exercise," La Gerche said.

The researchers tested the performance of the hearts in 17 athletes with right ventricular arrhythmias, 10 healthy endurance athletes and seven non-athletes.

They used several different imaging techniques to see the heart at rest and during exercise. They found that measurements of how well the heart was functioning when the athletes were resting were similar in all three groups, as was left ventricular function during exercise.

However, measurements taken while the participants were exercising showed changes in the functioning of the right ventricle in the athletes who were known to have arrhythmias when compared with the other two groups.

The dysfunction of the right ventricle during exercise suggests that there is damage to the heart muscle.

"This damage is causing both weakness and heart rhythm problems. While the weakness is mild, the heart rhythm problems are potentially life threatening," the authors said.

"It will be important to validate this study in a larger group of athletes and in athletes who are presenting for the first time in whom it is not yet clear whether or not their problem is serious," the authors added.

The paper was published in the European Heart Journal.