Life-Threatening Ventricular Tachyarrhythmia in Isolated Cardiac Sarcoidosis Compared With Cardiac Sarcoidosis With Extracardiac Involvement.

Although isolated cardiac sarcoidosis (CS) is not uncommon, little is known about the risk of life-threatening ventricular tachyarrhythmia. We aimed to evaluate the incidence of ventricular tachyarrhythmia in patients with isolated CS. A total of 94 patients with CS were enrolled. Isolated CS was diagnosed by histologic or clinical confirmation in the heart alone. The end points were sudden cardiac death, ventricular fibrillation, sustained ventricular tachycardia, or implantable cardioverter-defibrillator therapy for ventricular fibrillation or sustained ventricular tachycardia. A total of 25 patients were diagnosed with isolated CS, and 69 were diagnosed with CS with extracardiac involvement. As the initial cardiac manifestation leading to the CS diagnosis, 10 patients (40%) with isolated CS had ventricular tachyarrhythmia. Over the median follow-up of 48 months after the CS diagnosis, sudden cardiac death occurred in 2 patients (8%) with isolated CS. Ventricular fibrillation or sustained ventricular tachycardia, including implantable cardioverter-defibrillator therapy, occurred in 15 patients (60%) with isolated CS and 13 (19%) with CS with extracardiac involvement. The rate of ventricular tachyarrhythmia was higher in patients with isolated CS than in those with CS with extracardiac involvement (log-rank, p <0.01). Cox proportional hazard analysis showed that isolated CS was independently associated with ventricular tachyarrhythmia. A total of 2 or more ventricular tachyarrhythmias more frequently occurred in patients with isolated CS (52% vs 13%, p <0.01). Electric storm more frequently occurred in patients with isolated CS (24% vs 6%, p = 0.01). In conclusion, patients with isolated CS have ventricular tachyarrhythmia at a higher rate than those with CS with extracardiac involvement.