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(Ivanhoe Newswire) -- There are a few endurance athletes for whom regular athletic training will increase the risk of cardiac arrhythmias and even sudden death, especially among those in middle-age or who have a pre-existing cardiac disease.
"It's for this reason that sports medicine has focused on pre-participation screening," Dr. Luis Mont from the Hospital Clnic de Barcelona, Spain is quoted as saying, "in an attempt to detect any hidden heart disease."
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Disturbances in heart rhythm, particularly atrial fibrillation, which represents one of the major cardiovascular reasons for hospital admission, are more common among cyclists, marathon runners and other athletes with a long history of endurance training.
Dr. Mont reports that atrial fibrillation is more frequent in middle-aged individuals involved in regular endurance training. This includes individuals who formerly engaged in competitive sports and who continue to be active, as well as those who are active but who never actually participated in competitive sports. "So we have to look at the effects of endurance or athletic training with a more open view," Dr Mont was quoted as saying.
What does seem clear is that long-term endurance sport participation may well increase the incidence of cardiac arrhythmias, particularly atrial fibrillation, atrial flutter, sinus node dysfunction, and right ventricular premature beats. "Given the fact that an increasing number of individuals engage in regular endurance sports," says Dr Mont, "it is certainly of great interest to define which recommendations for sport should be implemented in an individual patient, and how best to manage arrhythmias in participants." Atrial fibrillation is the most common arrhythmic condition and carries the risk of sudden cardiac death.
Three papers presented by Dr Mont's group reflect the research effort now being directed toward sports cardiology and the prevention and treatment of rhythm disorders.
1. Efficacy of the circumferential pulmonary vein ablation (CPVA) of atrial fibrillation in endurance athletes. CPVA is a recently introduced technique, which identifies the signals causing the atrial fibrillation, and isolates their source in the pulmonary veins from the left ventricle of the heart. A series of 182 patients in Dr Mont's Barcelona clinic found that freedom of arrhythmias following CPVA was similar in the sports participants as in the regular patients. Left atrial size and long-standing atrial fibrillation were the only independent predictors for arrhythmia recurrence after the treatment, not sports participation.
2. A more basic science study from Dr Mont's group in Barcelona also suggests those with a history of arrhythmias following endurance training may benefit from a period of "deconditioning" following their efforts. The suggestion follows a study in animal models that found that markers of cardiac fibrosis in rats whose treadmill exercise was followed by a period of inactivity returned to control levels. Endurance exercise causes cardiac structural changes, including atrial and right ventricular fibrosis and this fibrosis may play a role in the development of arrhythmias.
3. Just as inactivity after training may inhibit cardiac fibrosis in animal models, a similar study suggests that the anti-hypertensive drug, losartan, prevents the heart fibrosis induced by endurance exercise. Markers of fibrosis were reduced by administration of losartan.
SOURCE: Papers presented to the European Society of Cardiology, June 21, 2009
This article was reported by Ivanhoe.com, who offers Medical Alerts by e-mail every day of the week. To subscribe, go to: http://www.ivanhoe.com/newsalert/.
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