Assessing outcomes in a cardiac sarcoid cohort with implantable loop recorders - a tertiary United Kingdom study

Cardiac sarcoidosis (CS) entails the inflammatory cardiac involvement of systemic sarcoid. Development of myocardial fibrosis can cause sustained ventricular arrhythmia (sVA), alongside high grade atrioventricular (hgAVB). In those patients who do not meet current international guidelines for implantable cardiac devices, implantable loop recorders (ILR) could be a feasible long term monitoring option. With only one current study in the literature, we sought to retrospectively assess outcomes in CS patients who underwent ILR insertion at Royal Brompton Hospital (RBH), the largest tertiary CS centre in the United Kingdom.

CS patients who underwent ILR insertion between 2014 and 2024 at RBH were identified. Only patients with multidisciplinary team meeting (MDT) diagnoses were included. Outcome measures assessed for included need for new implantable cardiac device, non-sustained ventricular tachycardia (NSVT), sVA, hgAVB, newly inserted ICD/CRT-D shock, all-cause-mortality and heart failure hospitalisation.

A total of 47 patients were identified with a median follow up of 2.79 years. There were 10 patients (21%) who sustained an adverse event, with 9 (19%) undergoing a new cardiac device implantation, 5 (11%) demonstrating NSVT, 5 (11%) demonstrating hgAVB and sVA noted in 4 (8.5%) patients. Those patients who sustained an event were compared with patients who did not; overall, only hypertension was significantly more prevalent in the event positive group.

In conclusion, this study has demonstrated that ILR insertion may be a useful long term surveillance tool in those CS patients who do not meet conventional device insertion criteria. Larger studies are prudent to clarify our findings.