P117 - HIGH INCIDENCE OF PACING-INDUCED CARDIOMYOPATHY IN PATIENTS WITH CARDIAC SARCOIDOSIS

Background: Clinically manifest cardiac sarcoidosis (CS) is encountered in approximately 5% of systemic sarcoidosis cases. CS may present with heart block, ventricular dysfunction, and/or ventricular arrhythmias (VA). Guidelines recommend cardiac implantable electronic devices (CIEDs) in all CS patients with advanced conduction system disease, and that implantable cardioverter-defibrillators (ICDs) are recommended in those who have an indication for permanent pacing. Importantly, however, guidelines do not provide recommendations for cardiac resynchronization therapy (CRT) in these patients. Among patients with CS, the incidence of pacing-induced cardiomyopathy (PICM) is not known; we hypothesized that PICM is more common in CS. Importantly, CS often involves the basal septum; this is a contraindication to conduction system pacing.

METHODS AND RESULTS: Patients in the Cardiac Sarcoidosis Multi-Center Prospective Cohort Study (CHASM-CS; NCT01477359) meeting the following criteria were analyzed: advanced conduction system disease, LVEF > 40% at presentation and CIED implantation. Patients were followed every 6 months. Data captured included patient demographics, clinical presentation, LVEF (baseline ± 3 months), lifetime average RV-pacing percentage, average RV-pacing percentage prior to device upgrade, RV apical lead position percentage, initial paced QRS duration, and FDG-PET data (baseline ± 3 months) (Table 1). ‘At risk for PICM’ was defined as RV pacing % consistently > 40%. ‘PICM’ was defined as absolute fall in LVEF > 10%.
Fifty patients were included in the study; all received immunosuppression. Twenty-two (44%) patients were identified to be at risk for PICM, of which 14/22 (63.6%) developed PICM, and 8/14 (57.1%) underwent CRT upgrade. Among patients with and without PICM, there were no differences in demographics, clinical presentation, baseline LVEF, lifetime average RV pacing, average RV pacing in the 12 months prior to device upgrade, RV apical lead positioning percentage, and mean initial paced QRS (Table 1). FDG-PET data showed that patients with PICM had a higher amount of scar (summed rest score (SRS) 6.3 ± 5.7 vs 2.0 ± 2.5, p = 0.041), specifically more septal scar (septal SRS 2.4 ± 3.3 vs 0.4 ± 0.7, p = 0.0004). There were no differences in number of segments with abnormal FDG uptake between groups (5.1 ± 4.7 vs 4.4 ± 3.3, p = 0.401).

Conclusion: Among patients with CS, the incidence of PICM was 14/22 (63.6%), compared to the rate of 5-15% published for undifferentiated patients. As such, up-front CRT should be considered in all patients with clinically manifest CS who present with advanced conduction system disease, regardless of LVEF.