IJCS | Volume 32, Nº4, July/August 2019

393 Lampert Sports participation for athletes with ICDs Int J Cardiovasc Sci. 2019;32(4):391-395 Review Article all sports for a period of time, most returned to sports later on, suggesting that the beneficial impacts of sports participation on quality of life outweighed the negative impact of shocks for most athletes. Programming the ICD in the athlete A recent subanalysis 19 has focused on the appropriate programming tominimize the likelihoodof inappropriate shocks in this population. In the ICD Sports Study, those athletes whose ICDs were programmed with higher rate-cut-offs for the first therapy zone (greater than 200bpm), and those programmed with detection- duration greater than the nominal settings, were less likely to receive inappropriate shocks, and those with both these settings, the least likely. 19 Programming was not prescribed in this study, but findings were similar to large randomized controlled studies in the general ICD population. 20 There was no increase in syncope prior to shock in those athletes with higher rate-cut-off/longer duration. While two athletes had ventricular tachycardia below the rate cut-off and thus not treated, the arrhythmias were minimally symptomatic, presenting as palpitations. There was no difference in shock-rates based on dual-versus-single chamber device, or number of therapy zones. Based on data from the ICD Sports Registry, in the updated “Eligibility and Disqualification Recommendations for Competitive Athletes With Cardiovascular Abnormalities: Task Force 9: Arrhythmias and Conduction Defects: A Scientific Statement From the American Heart Association and American College of Cardiology”, 21 competitive sports participation for patients with an ICD no longer carries a blanket restriction, but rather, a “IIB” recommendation, i.e., “may be considered”. Factors in the decision-making process around return to play: importance of the underlying disease What factors need to be considered in the decision- making process around return to play for an athlete with an ICD? The most important one is the underlying disease. The ICD Sports Registry has not evaluated if or to what degree vigorous exercise may exacerbate the progression of cardiomyopathies. While in that study the ICDwas always successful at converting ventricular arrhythmias in patients with arrhythmogenic right ventricular cardiomyopathy (ARVC,) these were the patients most likely to experience both single and storms of ventricular arrhythmias during sports. Furthermore, there are increasing data in both animals 22,23 and human patients 24,25 that high-level exercise may accelerate cardiomyopathy progression in this disorder. For patients with ARVC, the disease process, rather than the ICD itself, should guide the risk-evaluation of sports participation. How exercise may impact the myopathic process in HCM is yet to be clarified. In a murine model of HCM, exercise was actually beneficial. In animals who had not yet developed the HCM phenotype, exercise prevented fibrosis and myocyte disarray, and in animals who had already developed HCM, exercise led to disarray regression and to improvements in the apoptotic signaling pathway components. 26 In a recent study of controlled increases in moderate exercise in sedentary HCM patients, 27 physical conditioning improved, there were no arrhythmias, and no changes in echo parameters, although this was a short intervention, and did not include maximal vigorous exercise. Catecholaminergic polymorphic VT (CPVT) is unique in that an ICD is not nearly as successful at converting an arrhythmia as it is in other arrhythmogenic conditions. 28 ICD shocks increase catecholamines, even in a sedated patient 17 and this can create a vicious cycle of arrhythmia recurrence for a patient with CPVT. One small series has described appropriately-treated CPVT patients, mostly without ICDs, participating in sports. 29 In one series of 15 CPVT patients with ICDs, 6 were treated for ventricular arrhythmias. Two died of VT refractory to ICD treatment, including one whose VT was triggered by an inappropriate shock for AF. 28 In the ICD Sports Registry, another subset of patients with ventricular arrhythmias requiring multiple shocks for termination were those with “idiopathic VF”. As CPVT is electrically silent at rest, it is highly possible that some “idiopathic VF”may represent undiagnosed CPVT. Treadmill testing is imperative to evaluate CPVT, and genetic testing should be considered. Factors in decision-making: sports The type of sports should also be taken into consideration. In the ICD Sports Registry, there were few athletes engaged in high-level contact sports. Basketball and soccer, which are considered “contact sports” by the American Academy of Pediatrics, 30 comprised a significant proportion of the sports practiced by the athletes, but there were very few engaged in sports in