BOSTON – Athletes with implantable cardioverter defibrillators may not need to be sidelined when the action gets fast and furious, say investigators in a multicenter study presented at the annual meeting of the Heart Rhythm Society.

Although international consensus statements caution against anything more vigorous than golf, bowling, or billiards for people with ICDs, an analysis of data from a prospective, multinational registry shows that although 10%* of athletes with ICDs received a shock from their devices during competition or practice, there were no serious adverse events, reported Dr. Rachel Lampert of the division of cardiology at Yale University, New Haven, Conn.

"Shocks were not rare during sports. However, no serious health consequences occurred. Most patients returned to sports having received shocks while playing, implying that the negative impact on quality of life of the shocks was offset for them on the quality of life from sports participation," Dr. Lampert said.

The findings suggest that the decision to return to a sport or quit it after an ICD implantation should be individualized, she added.

Dr. Hugh Calkins, professor of cardiology at the Johns Hopkins Heart and Vascular Institute, Baltimore, and vice president of the Heart Rhythm Society, said in an interview that he is comfortable with allowing many but not all patients with ICDs to return to an active sport.

"The one exception is arrhythmogenic right ventricular dysplasia, where exercise actually causes the disease to progress. That’s very different from the long QT or the Brugada syndrome, where exercise doesn’t have any impact on the underlying disease or disease progression," said Dr. Calkins, who was not involved in the study.

Dr. Lampert and her colleagues recruited 372* athletes aged 10-60 years (median, 33 years) with ICDs who participated in either competitive or dangerous sports (defined as any sport where sudden loss of control could cause injury).

The athletes were self-enrolled and volunteered to participate after learning of the study from patient-advocacy groups, mailing lists, or word of mouth. The investigators interviewed the athletes by telephone and obtained their medical records for capturing sports-related and clinical data, then followed up with phone calls every 6 months.

In all, 67% were male and 94% were white, with a mean time since initial ICD implantation of 27 months. The mean left ventricular ejection fraction was 60%. Nearly two-thirds (62%) were taking beta-blockers. The primary cardiac diagnoses included long QT syndrome, hypertrophic cardiomyopathy, arrhythmogenic right ventricular cardiomyopathy, and coronary artery disease.

Competition was at the elite amateur level, which the authors defined as interscholastic varsity or junior varsity, or regional or national competitions.

During the median 31 months of follow-up, two patients died: a 52 year-old cyclist with coronary artery disease died at his desk at work after receiving multiple shocks; and a 34-year-old volleyball/basketball player with familial cardiomyopathy who died during a hospitalization for heart failure. Additionally, 9 patients were lost to follow-up (all were confirmed still alive), 6 withdrew, and 4 developed worsening cardiac or medical conditions precluding sports, leaving 351* patients for the analysis.

There were no cases of the primary end point: either tachyarrhythmic death or externally resuscitated tachyarrhythmia during or after sports, or of injury due to arrhythmia or shock during sports.

Overall, 77 patients received at least one shock during the study, 37 during sports. Of this group, four stopped sports completely, and seven stopped one or more sports. Five patients stopped participating in at least one sport because of shocks they received at rest or at other times when playing a sport.

Seven patients had eight ventricular arrhythmias requiring multiple shocks to (two to six) to terminate the event, occurring in patients with catecholaminergic polymorphic ventricular tachycardia, idiopathic ventricular fibrillation, or coronary artery disease.

There were 13 definite lead malfunctions, defined as noise on a lead or change in pacing parameters with a visualized lead abnormality, and 14 probable lead malfunctions (change in pacing function only).

Freedom from lead malfunction at 5 years from the time of implant was 93%, and at 10 years was 84%.

Dr. Lampert acknowledged that the study was limited by lack of a control group; patient self-selection, which may have led to underrepresentation of athletes who have received ICDS; and limited follow-up.

Nonetheless, "these data do not support blanket restriction of athletes with ICDs from participating in sports," she concluded.

The investigator-initiated study was supported by Medtronic, St. Jude Medical, and Boston Scientific. Dr. Lampert disclosed receiving honoraria from two of the companies (not specified). Dr. Calkins has previously consulted for and received research support from Medtronic.

*Correction, 5/14/12: An earlier version of this article misstated the number of patients and thus the percentage of patients receiving shocks.

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