Update on Sports Participation for Athletes with Implantable Cardioverter Defibrillators

Prior statements have recommended restriction from competitive sports participation for all athletes with ICDs. Recent data, however, suggests that many athletes can participate in sports without adverse events. In the ICD Sports Registry, 440 athletes, aged 8-60 years, 77 of which were high-level interscholastic athletes, who had continued to practice sports, were prospectively followed for 4 years, with no deaths or failures to defibrillate during practice, and no injuries related to arrhythmia or shock during sports. Shocks did occur, for ventricular and supraventricular arrhythmias. While more athletes received shocks during physical activity than at rest, there were no differences between competition or practice, versus other physical activity. Programming with higher rate cut-offs and longer durations was associated with fewer inappropriate shocks, with no increase in syncope. Based on this study, current recommendations now state that returning to competition may be considered for an athlete with an ICD. In considering this decision, the underlying disease and type of sport should be discussed, and shared decision-making between doctor, patient, and often family, is critical

Slow QT interval adaptation to heart rate changes in normal ambulatory subjects.

BACKGROUND: Clinical formulas for QT correction utilize instantaneous HR. We showed previously that longer-term HR affects QT duration. We extend these findings, identifying more accurate models of QT behavior. METHOD: Multiple models of QT dependence on HR were tested in 2 independent populations. Holter recordings were analyzed in population A (healthy volunteers, n = 14, 6 males, age 26.9 ± 12.3 yr). The hypotheses generated in population A were tested in an independent group population B, healthy volunteers, n = 15, 9 males, age 52.9 ± 15.6 yr). Linear models of QT interval dependence on a weighted average of RR intervals in the preceding 3 minutes were compared to models based on the immediately preceding RR interval (instantaneous HR). RESULTS: In population A, linear models based on RR intervals over the preceding minute performed better than the best nonlinear model based on the single RR interval immediately preceding the QT interval. Linear models including HR values preceding the QT interval by more than 60 s further improved model fit. This model hierarchy was confirmed in population B. Linear formula for QT correction based on exponential decay of HR effect with 60 s time constant outperformed Bazett and Fridericia formulas in both populations. CONCLUSIONS: QT duration in normal ambulatory subjects is affected by noninstantaneous HR, including HR history dating back more than 60 s. Exponential decay of this "memory effect" with time constant of 1 minute provides an accurate description of QT adaptation. This may be of clinical importance when HR is not steady.