Cardiac sarcoidosis – when should you insert a defibrillator?


Take Home Messages
  • Cardiac sarcoidosis is underdiagnosed and is associated with high rates of life-threatening ventricular arrhythmia.
  • There are three main international guidelines that advise, with varying degrees of evidence, on when an ICD should be implanted in cardiac sarcoidosis (CS).
  • Over 50% of those with CS who do not initially meet Class I or IIa indications (HRS criteria) for an ICD later went on (5 year follow-up) to develop one of these, or experienced sudden cardiac death (SCD) or sustained ventricular arrhythmia.
  • Patients with a definite histological diagnosis of cardiac sarcoidosis were shown to be at significantly higher risk of SCD than those without.
  • This study signifies the importance of regular outpatient follow-up in those with cardiac sarcoidosis, particularly in those who may not initially meet ICD indications.

Sarcoidosis is a multisystem inflammatory disorder of unknown aetiology characterised by the presence of non-necrotizing granulomas. Myocardial involvement, termed cardiac sarcoidosis (CS), occurs in up to 30% of cases and can manifest with an initial presentation of high degree atrioventricular block, ventricular arrhythmias, heart failure and sudden cardiac death (SCD) (1). Investigations to aid diagnosis include echocardiogram, cardiac MRI, FDG-PET scan and endomyocardial biopsy (EMB) (2,3).  Implantable cardiac defibrillator (ICD) use in CS has been widely shown to reduce risk of SCD from life-threatening arrhythmias, but factors that identify the most appropriate recipients remains unclear and is the focus of research across the world. One area of excellence spearheading new research around this topic is in Finland (4), with ongoing analysis of the MIDFIN registry – a 5-centre cardiology network first established in the 1980’s.