Management of ventricular tachycardia in patients with cardiac sarcoidosis

Sarcoidosis is a multisystem granulomatous disease with 2 different phases (inflammation and scar). In the current era of targeted use of implantable cardioverter-defibrillators and modern heart failure therapy, recent data indicate the prognosis of cardiac sarcoidosis (CS) is much improved, and hence more patients are presenting with recurrent ventricular tachycardia (VT). This review highlights our current understanding of the pathophysiology and management of ventricular arrhythmias in CS with the major focus on indications, techniques, and outcomes of ablation. It is likely macroreentry phenomena around areas of fibrosis is the most frequent mechanism of ventricular arrhythmia in CS. It is also possible that inflammation may play a role in initiating reentry with ventricular ectopy in CS patients, or by slowing conduction in diseased tissue. The best available data would suggest annual rates of VT of perhaps 1%-2% and 10%-15% in patients with initially clinically silent and clinically manifest disease, respectively. Current guidelines recommend a stepwise approach to VT management. The first suggested step is treatment with immunosuppression if there is evidence of active inflammation. Antiarrhythmic medications are often started at the same time, with catheter ablation considered if VT cannot be controlled. Activation and entrainment mapping and ablation are favored in the setting of hemodynamically tolerated VT. Substrate ablation targets areas of abnormal electrogram and favorable pace mapping using linear and/or cluster lesion sets with the goal of abolishing critical isthmuses and/or blocking VT exit sites. Epicardial mapping ablation is required in 20%-35% of cases. In general, more morphologies of VT are induced (often 3-4) and subsequent outcomes (recurrence rates 40%-50%) are less favorable than in other forms of nonischemic cardiomyopathy. The prognosis of CS is much improved and, as a result, more patients are developing VT during follow-up. Likely principally related to the complex disease substrate, VT ablation is technically challenging, with moderate outcomes, and much remains to be learned.