AimsIn cardiac sarcoidosis (CS) patients, the benefit of cardiac resynchronization therapy (CRT) remains unclear. We sought to assess the short‐term and long‐term effects of CRT in CS patients with a range of left ventricular (LV) ejection fractions (LVEFs).MethodsConsecutive CS patients with heart failure with reduced ejection fraction (HFrEF; LVEF ≤ 40%), mildly reduced ejection fraction (HFmrEF; LVEF 41%–49%) and preserved ejection fraction (HFpEF; LVEF ≥ 50) treated with CRT under the care of a tertiary UK centre between 2008 and 2023 were reviewed. CRT response was defined by >5% improvement in serial LVEF. The primary endpoint was a composite of all‐cause mortality, cardiac transplantation or unplanned hospitalization for decompensated heart failure. The secondary endpoint included ventricular arrhythmic events.ResultsOf the 100 patients enrolled (age 58 ± 10 years; 71% male), 63 had HFrEF, 17 had HFmrEF and 20 had HFpEF. After short‐term follow‐up (9.8 ± 5.4 months), HFrEF patients demonstrated significant LVEF response (P < 0.01). On Kaplan–Meier analysis (follow‐up 38 ± 32 months), HFrEF non‐responders had significantly worse event‐free survival compared with HFrEF responders for the primary (P < 0.001) and secondary (P = 0.001) endpoints. Despite short‐term LV function improvement, CRT responders still had worse event‐free survival compared with HFmrEF/HFpEF patients for the primary endpoint (P < 0.001). On multivariable Cox analysis, age [hazard ratio (HR) 1.05, 95% confidence interval (CI) 1.01–1.10, P = 0.008] and HFrEF CRT non‐response (HR 12.33, 95% CI 2.45–61.87, P = 0.002) were associated with the primary endpoint.ConclusionsIn CS patients with HFrEF, CRT response is associated with a better long‐term prognosis than non‐response. However, HFrEF CRT responders still have worse long‐term prognosis than HFmrEF/HFpEF patients.
