Introduction: Hypertrophic cardiomyopathy (HCM) is the commonest inherited heart disease. Implantable cardioverter defibrillators (ICDs) are routinely implanted to protect against risk of sudden cardiac death (SCD) in those patients who meet criteria. Whilst the consequence of not having an ICD when needed is clear, the implantation of cardiac devices is not without short and long-term risks to the patient. We sought to evaluate the ICD complication rate in HCM patients and place them in context with the frequency of appropriate therapies delivered.
Methods: We retrospectively assessed consecutive patients who underwent ICD implantation between July 2016 and October 2018 and were coded as hypertrophic cardiomyopathy in the device database (MediConnect™). HCM diagnosis was confirmed by reviewing implant procedure notes, and only new device implants were included
(excluding generator changes). Complications were described according
to timing, with acute considered in the same admission, and late
Results: Between July 2016 and October 2018, 136 HCM patients underwent ICD implantation, 127 (93%) for primary prevention of SCD. During 261.1 patient years of follow-up (mean 1.9 ± 0.7 years), there were 3 deaths, 2 from cardiac cause (myocardial infarction). 8 patients (5.9%) received appropriate therapies. 7 patients had both a shock and anti-tachycardic pacing (ATP), and one patient had ATP alone. 6 patients (4.4%) received an inappropriate shock. 4 patients (2.9%) experienced acute complication, including pericardial effusion / tamponade, a torn cephalic vein after difficult access, right atrial lead displacement/loss of function requiring revision, and finally high lead impedance with a new lead required. 6 patients (4.4%) experienced late complications, including right ventricular lead displacement/loss of function requiring revision (2), atrial lead displacement (2), wound infection requiring antibiotics (1), and high shock impedance at follow-up (1). Adverse ICD events (inappropriate shocks and / or device complications) were seen in 16 patients (12%) or 4.5%/year.
Conclusions/implications: Over a relatively short follow-up period, occurrence of appropriate device therapy was low. The adverse ICD event rate was in line with published data, but the relatively high occurrence of inappropriate shocks signals this is an important complication to discuss with patients given the lasting psychological impact of such an event.