First study about the influence of physical deconditioning on ventricular tachyarrhythmias

When athletes with irregular heartbeats are advised to stop intensive training, the arrhythmias often subside, and this response may help physicians decide which athletes may reenter competition, according to a new study in the Sept. 1, 2004 issue of the Journal of the American College of Cardiology.

“This is the first study about the influence of physical deconditioning on ventricular tachyarrhythmias. We demonstrated that after a brief period of physical deconditioning the ventricular tachyarrhythmias are markedly reduced; that’s the most important point of this study,” said Alessandro Biffi, M.D. with the National Institute of Sports Medicine and Italian Olympic Committee in Rome, Italy.

Dr. Biffi said that in athletes who do not have signs of heart disease or cardiac abnormalities, the response they saw may be part of “athlete’s heart,” the enlarged heart commonly seen in athletes who undergo intense endurance training.

“The clinical significance is that if ventricular arrhythmia is reduced after deconditioning, then it is probably a benign condition,” Dr. Biffi said.

The researchers studied 70 athletes in Italy who had been advised to stop competing after routine screening tests discovered frequent and complex irregular, fast heart rhythms known as ventricular tachyarrhythmias. These arrhythmias are linked to an increased risk for sudden death. One athlete who died during a field hockey game was excluded from the analysis. The researchers also studied heart rhythms in a control group of 148 athletes who had rhythms within normal ranges and who continued training.

The researchers found a significant decrease in the frequency and complexity of ventricular arrhythmias after deconditioning. In 50 of the 70 athletes (71 percent), ventricular arrhythmias decreased substantially after they stopped training. Most of these athletes with reduced arrhythmias did not have structural cardiovascular abnormalities (37 of 50; 74 percent). These athletes resumed competitive sports. During a follow-up period that averaged eight years, each of the 70 athletes survived without cardiac symptoms.

“In this study we usually did three months of deconditioning, which is probably enough to see whether the arrhythmia is reduced or not after deconditioning,” Dr. Biffi said.

The researchers wrote that “resolution of ventricular tachyarrhythmias with deconditioning may justify resumption of competition without risk in these athletes without heart disease.”

In an editorial in the journal, Kyoko Soejima, M.D. and William G. Stevenson, M.D., F.A.C.C. at Brigham and Women’s Hospital, Harvard Medical School in Boston noted that the researchers obtained only two heart rhythm measurements for each patient and that there is substantial natural variability in arrhythmias, so they can’t be absolutely certain that the changes in arrhythmias seen in the study were specifically related to a training effect. Nevertheless, they agreed that the risk of sudden death is quite low in these athletes.

“A decrease in ventricular arrhythmias produced by detraining may further support the safety of allowing a return to athletics, but does not exclude the possibility of underlying heart disease. A careful cardiac evaluation and case-by-case assessment is required,” Dr. Stevenson said.

The evaluations would include reviewing the athlete’s family history, recording an electrocardiogram, ultrasound examination and exercise stress testing.

The American College of Cardiology, a 31,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy.