Pacing burden and device therapies in middle-aged patients with cardiac sarcoidosis as compared with idiopathic high-degree atrioventricular block - an intermediate term follow up

Introduction: Atrioventricular block (AVB) may be idiopathic or a secondary manifestation of an underlying systemic disease. Cardiac sarcoidosis (CS) is an important underlying cause for high-degree AVB (HDAVB), posing diagnostic challenges and significant clinical implications. The current Study evaluated pacing parameters and device therapies in patients diagnosed with HDAVB due to CS as compared with idiopathic HDAVB.

Methods: We evaluated all patients aged 18-65 years presenting with otherwise unexplained HDAVB, who were systematically referred for cardiac magnetic resonance imaging (CMRI) and/or PET-CT prior to pacemaker implantation. All patients were periodically evaluated at the pacemaker clinic with device parameters and therapies systematically recorded.

Results: Overall, 30 patients with HDAVB were included. The median age was 56.5 years (IQR 53.00, 61.75). All CS patients were implanted with an ICD, while immunosuppressive therapy was initiated within a mean of 13 days from ICD implantation. During a follow-up of 3 years it was observed that ventricular pacing burden was higher in CS patients ((mean 69.40% (SD 43.19) vs mean 59.55% (SD 47.72), P-value 0.587, in CS as compared with idiopathic HDAVB patients, respectively)). However, over time, ventricular pacing burden in CS patients decreased significantly ((mean 50% (SD 50.47) at 1 year to mean 47.70% (SD 49.20) at 2-years, and mean 43.00% (SD 48.18) at 3-years post implant, P-value 0.74, 0,41 and 0.28 respectively)). During the entire follow-up period, none of the CS patients required ICD therapy delivery, while 2 patients (10%) from the idiopathic HDAVB group had sustained ventricular arrhythmias. In terms of mortality, 2 cases of all-cause mortality recorded, both in patients with cardiac sarcoidosis (P=.1, compared with idiopathic high-grade atrioventricular block).

Conclusions: The intermediate-term outcome including sustained ventricular arrhythmias is favorable and similar in both idiopathic and CS related HDAVB. The burden of ventricular pacing in patients with CS is maximal early on, before the effect of immunosuppressive therapy. Thereafter it declines steadily while the opposite is observed in idiopathic HDAVB patients.