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Introduction In patients with cardiac sarcoidosis (CS), recent evidence suggests that non-sustained ventricular tachycardia (NSVT) and elevated ventricular ectopy (VE) burden (defined as >5%) are predictors of adverse clinical outcomes. However, the origins of NSVT and elevated VE burden in patients under workup for CS remain unclear, which hampers the general applicability of this risk marker for determining clinical management. This study investigated the predictors of NSVT and elevated VE burden in suspected cardiac sarcoidosis patients.Methods This study included patients with suspected CS who underwent workup with cardiovascular magnetic resonance (CMR) and FDG-PET-CT, between November 2020 and November 2024. The occurrence of NSVT and/or elevated VE burden were recorded from holter monitors and/or clinical notes.Results A total of 78 patients with suspected CS (age 59±15yrs; 71% males) had a mean LVEF of 55±12% and mean RVEF of 55±12%. Of the 78 patients, 10 (13%) developed NSVT and/or elevated VE burden. Of the risk factors, the commonest were hypertension (26%), diabetes mellitus (17%), ischaemic heart disease (IHD; 10%). On CMR, LV systolic dysfunction (LVEF<50%) was detected in 32/78 (41%) of patients and evidence of myocardial fibrosis (by LGE) was found in 56/78 (72%) of patients. On FDG-PET-CT, myocardial inflammation (defined as FDG-uptake in the LV greater than low grade as determined by a nuclear cardiology consultant) was present in 13/78 (17%) of patients. On multivariate regression analysis (including age, gender, hypertension, IHD, LVEF<50%, LGE and FDG-uptake), independent predictors of NSVT and elevated VE burden were hypertension (Rpartial 0.275; p=0.020), IHD (Rpartial -0.301; p=0.011) and LVEF<50% (Rpartial 0.266; p=0.020). Neither LGE presence (Rpartial -0.014; p=0.908) nor myocardial FDG-uptake (Rpartial -0.116; p=0.337) were independent predictors of NSVT and elevated VE burden.Conclusions In this cohort of patients with suspected CS, conventional risk factors such as LVEF<50%, hypertension and ischaemic heart disease history were associated with NSVT and elevated VE burden. The high prevalence of patients with LV myocardial fibrosis (by LGE) may have blurred its known association with ventricular arrhythmias in this study cohort. Myocardial inflammation did not appear associated with NSVT or elevated VE burden. The findings emphasise the importance of managing conventional risk factors in CS patients, in addition to myocardial inflammation.