Exercise capacity after PVI
MILAN, ITALY. According to the Italian National Eligibility Guidelines for Continuing Sport Participation, patients with symptomatic atrial fibrillation and those on anticoagulation are prohibited from participating in competitive sports. Thus, it is of considerable interest to establish whether competitive athletes with afib can meet eligibility requirements after a successful pulmonary vein ablation (PVI). Researchers at the University of Milan now report on a clinical trial to determine this.

The trial involved 20 male athletes (average age of 44 years) who, after participating in competitive sports (cycling, long-distance running, soccer, and skiing) for an average of 25 years, had been disqualified because of symptomatic lone AF. Fourteen (70%) of the athletes experienced paroxysmal LAF, while the remaining 6 had the persistent variety. The study participants had suffered from afib for an average of 3 years and had failed 3 or 4 antiarrhythmic drugs (quinidine, flecainide, propafenone, and sotalol). They often experienced episodes during training. The impact of afib on the physical performance of the athletes was assessed by comparing pre-ablation maximal exercise performance (MEP) with post-ablation MEP, as well as with the average MEP measured in a group of matched athletes without AF.

All study participants underwent a segmental PVI accompanied by a flutter ablation, if indicated. At least 3 months after the first procedure, all participants underwent a planned second electrophysiology study and re-isolation of veins that had regained conductivity. The researchers noted that 81% of 77 veins isolated during the first procedure had regained some conductivity. Five patients (25%) needed a third procedure to achieve complete isolation. During a 3-year follow-up, 90% of the group were free of afib without the use of antiarrhythmics, and the remaining 2 patients were still experiencing infrequent, short episodes. All study participants were able to resume full training and met eligibility requirements 6 months after their final procedure.

The athletes underwent stress testing pre- and post-ablation. Prior to the first ablation the average MEP was 183 W with athletes experiencing afib during the stress test having a lower MEP (176 W) than those remaining in normal sinus rhythm (207 W). After the final ablation the average MEP in the group was 218 W, still somewhat lower than the average 231 W recorded among matched athletes who had never experienced AF. It is of interest to note that 65% of study participants went into afib during training indicating adrenergic dominance, while at the same time 78% experienced episodes at night indicating vagal dominance.

In an accompanying editorial, Dr. Rachel Lampert of the Yale University School of Medicine gives an elegant explanation for this seeming paradox. Says Dr. Lampert,

  • "Data have also shown that sympathetic stimulation decreases atrial effective refractory period. Most relevant to the situation of the trained athlete are studies demonstrating that sympathetic activation acts synergistically with vagal stimulation to shorten the atrial refractory period further than either branch of the autonomic nervous system acting alone."
  • "These findings imply that while both adrenergic and vagal activity can induce AF, the interaction between high levels of sympathetic and parasympathetic activity is particularly arrhythmogenic, a situation analogous to intense exercise in the trained athlete."
Furlanello, F, et al. Radiofrequency catheter ablation of atrial fibrillation in athletes referred for disabling symptoms preventing usual training schedule and sport competition. Journal of Cardiovascular Electrophysiology, published online, February 8, 2008
Lampert, R. Atrial fibrillation in athletes: toward more effective therapy and better understanding. Journal of Cardiovascular Electrophysiology, published online, March 21, 2008

Editor's comment: It is clearly of great comfort to competitive athletes that it is possible to restore their ability to compete through extensive pulmonary vein isolation. Whether they will achieve their full pre-afib capacity is open to question since the average MEP after ablation was still only 218 W as compared to the 231 W measured in a group of matched non-afib athletes. The observation that intense exercise increases activation of both the sympathetic (adrenergic) and parasympathetic (vagal) nervous system resulting in a shortened atrial refractory period is of particular interest in explaining why competing athletes are more prone to developing lone afib than are less intense exercisers. Finally, the finding that 81% of ablated veins had regained some conductivity after the initial ablation goes a long way toward explaining the now quite common need for a "touch-up" ablation.