(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 Clínic de Barcelona, Spain is quoted
as saying, "in an attempt to detect any hidden heart disease."
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
