Abstract 4123956: Upgrade to Implantable Cardioverter-Defibrillator in Patients Diagnosed with Cardiac Sarcoidosis after Permanent Pacemaker Implantation for High-Grade Atrioventricular Block

Introduction: Unexplained high-grade AV block (AVB) in patients age <65 years is among the salient features of cardiac sarcoidosis (CS). Guidelines recommend that CS patients with high-grade AVB should receive an implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy-defibrillator (CRT-D) rather than a permanent pacemaker (PPM). However, in clinical practice, CS may be recognized after PPM implantation for high-grade AVB. Aims: To evaluate the characteristics and outcomes of patients diagnosed with CS after PPM implantation for high-grade AVB and assess the decision-making and rationale for upgrade to ICD/CRT-D. Methods: Retrospective review of the Mayo Clinic Sarcoid Registry (n=848) was performed to identify all patients for which a PPM was implanted for high-grade AVB prior to the diagnosis of CS. Baseline clinical and imaging characteristics were collected during index evaluation at our institution. Decision-making for ICD upgrade, lead management strategy, immunosuppression initiation, and outcomes were assessed. Results: Overall, 29 of 848 (3.4%) of CS patients (62% probable/definite CS; 77% male; median (IQR) age 56 (48-61) years; and median (IQR) LVEF 58% (50-62) received a PPM for high-grade AVB prior to a CS diagnosis. Median (IQR) interval between PPM implant and index evaluation was 10 (3-23) months. Eight of 29 patients underwent upgrade to ICD (n=4) or CRT-D (n=4). Among them, the pacing lead was extracted in 4. All patients were upgraded for primary prevention of sudden cardiac death (SCD), with 3 of them also having LVEF<50% requiring upgrade to CRT-D. Twenty-two (79%) patients in the total cohort were treated with immunosuppression. During median (IQR) follow-up 37 months (11-74), 1 patient in the upgrade group had sustained VT appropriately treated with anti-tachycardia pacing. No events were documented among patients in the non-upgrade group. At last follow-up, 6 (75%) patients in the upgrade group and 12 (57%) in the non-upgrade group were pacemaker dependent. Median LVEF change was 0% in patients who underwent upgrade to CRT-D and –0.2% in those who underwent upgrade to ICD or no upgrade. Conclusions: In this cohort of patients diagnosed with CS several months after a PPM had been implanted for high-grade AVB, incident VT/VF was infrequent with contemporary CS management. In the absence of other SCD risk factors, CS patients who received a PPM for high-grade AVB prior to their CS diagnosis may not require ICD upgrade.