Preserving active lifestyle: subcutaneous defibrillators in young patients engaged in recreational sports. Insights from a multicenter study

Background Leading an active lifestyle and participating in recreational sports are crucial for overall well-being and cardiovascular health. Many young patients with implantable defibrillators engage in these activities, but the safety for subcutaneous defibrillator (S-ICD) recipients is unknown. Purpose Evaluate how lifestyle and recreational sports affect the risk of appropriate (AS) and inappropriate shocks (IAS) in S-ICD recipients. Methods We enrolled consecutive young S-ICD recipients (14-65 years) from 19 Italian centers and assessed their physical activity with the International Physical Activity Questionnaire (IPAQ). During follow-up, we analyzed the impact of lifestyle and recreational sports on AS and IAS. Results We enrolled 602 S-ICD recipients (77% males; age: 46±14 years). Common diagnoses included hypertrophic cardiomyopathy (24%), ischemic heart disease (20%), and idiopathic dilated CM (17%). IPAQ was administered 47 months (IQR: 26-68) post-SICD implantation. According to the IPAQ, patients were categorized as inactive subjects (IS; 27.9%), minimally active subjects (MAS; 43.7%), or highly active subjects (HAS; 28.4%). Patients with progressively higher activity levels had, in parallel, younger age (48±14 vs. 45±13 vs. 44±13 years; p=0.02) and higher ejection fraction (EF, %) (46±16 vs. 48±15 vs. 49±16; p=0.09). 163 patients (27.1%) regularly participated in recreational sports, with fitness/gym (25.2%), walking (20.9%), and cycling (14.1%) as the most common choices. As compared to patients not engaged in sports, recreational athletes were younger (43±13 vs 47±14 years; p<0.01) and had higher EF (52±14 vs 46±16; p<0.01). During follow-up (32 months; IQR 19-54), there were 77 discrete VT/VF episodes and 10 storms in 44 patients treated with AS. Also, there were 38 discrete IAS and 7 inappropriate shock storms in 39 patients. IS, MAS and HAS had similar rates of AS (9.5% vs 6.8% vs 5.8%, respectively; p=0.39) and IAS (4.8% vs 6.5% vs 8.2%, respectively; p=0.44). Kaplan-Meier curves showed similar cumulative rate of first AS (p= 0.12) or IAS (p= 0.74) for the 3 groups (Figures 1 and 2). Recreational athletes and non-athletes were propensity matched for age, sex, heart disease, EF, and primary/secondary prevention ICD implantation. Non-athletes and recreational athletes had similar risk of AS (HR: 1.78; 95% CI: 0.75-4.41; p=0.20) and IAS (HR: 1.20; 95% CI: 0.55-2.64; p=0.64). Out of 163 recreational athletes, 7 (4.3%) experienced 12 distinct AS, of which 3 (25%) occurred during sport activities. There were no arrhythmic storms while engaging in sports. Additionally, 15 patients (9.2%) had 17 episodes of IAS, with 3 (17.6%) occurring during sport practice. Conclusions In young S-ICD recipients, those leading more active lifestyle and commonly engaged in recreational sports were not exposed to a higher risk neither of appropriate, nor of inappropriate shocks. However, shocks related to sport practice were not uncommon.