Gender-specific differences in young patients receiving implantable cardioverter-defibrillator therapy - a subgroup analysis of the german device registry

FUNDING ACKNOWLEDGEMENTS: Type of funding sources: None. BACKGROUND: Implantable cardioverter-defibrillator (ICD) and cardiac resynchronization therapy defibrillators (CRT-D) are well established therapies in heart failure. Therapeutic and technological advancements led to increasing numbers of younger patients receiving these devices. Distinguishing patient characteristics among this younger patient cohort, especially gender-specific differences, are important to optimize patient care. METHODS: Between 2007-2014 the German DEVICE registry enrolled patients from 50 German centers undergoing ICD/CRT-D implantation. Patient characteristics, data on procedural outcome and adverse events during index hospitalization and 1-year follow-up were recorded. All patients under the age of 45 years were identified, separated into two groups according to their gender and analyzed. RESULTS: Out of 4181 patients enrolled, 236 patients (5.6%) were under the age of 45 years, of which 162 patients (68.6%) were male and 72 patients were female (31.4%). Male patients were older (39.5 [35.0; 42.0] vs. 34.0 [28.0; 40.0] years, p<0.001) and were more likely to suffer from cardiac disease (77.2 vs. 59.5%, p=0.005) and non-cardiac comorbidities (24.1 vs. 12.2%, p=0.035). The prevalence of Long-QT syndrome was markedly increased in female patients (1.9 vs. 10.8%, p=0.002). Male patients had lower mean left-ventricular ejection fraction (39.8±18.5 vs. 49.5±16.7%, p=0.003), were less likely to be in NYHA functional class I (44.0 vs. 61.4%, p=0.047) and received more betablockers (80,2% vs. 64,9%; p=0,011), ACE-inhibitors (56,2% vs. 46,5%; p=0,005) and statins (27,5% vs. 10,8%, p=0,005). Dual-chamber ICD were more common in female patients (13.0 vs. 27.8%, p=0.006) with a trend towards higher prevalence of pathological AV-conduction in female patients (6.2% vs. 13.5%, p=0.06). There were no differences in the number of implanted CRT-D devices between groups (9.3 vs. 6.9%, p=0.56). There was no detectable difference in overall post-operative complications (1.9 vs. 5.4%, p=0.21) with no cases of in-hospital mortality in both groups. However, there were more pneumothoraces requiring a chest tube insertion in female patients (0.0% vs. 4,1%, p=0.03). Median follow-up time was 514 [398; 669] days. There were no differences in neither device-associated complications requiring revision (15.0 vs. 19.1%, p=0.52), nor in all-cause mortality (3.7 vs. 1.9%, p=0.52; HR 0.5, 95%CI: 0.06-4.27) after 1-year of follow-up, but female patients had a higher mean number of rehospitalizations (1.6±1.5 vs. 2.1±1.3; p=0.026). CONCLUSION: In young patients under 45 years, there were no differences in overall device complications and overall mortality between male and female patients after implantation and after 1-year follow-up. Even though female patients had less cardiac and non-cardiac (co-)morbidities, the number of rehospitalizations after 1-year follow up were higher.