Efficacy of Ivabradine in Preventing Inappropriate Shock due to Sinus Tachycardia in a Patient with Cardiac Sarcoidosis.

We herein report a case of left ventricular dysfunction due to cardiac sarcoidosis following cardiac resynchronization therapy defibrillator (CRT-D) in an 87-year-old man. He presented to our hospital after receiving shock therapy while conscious. Device interrogation revealed that inappropriate shock occurred due to sinus tachycardia. Due to the setting of a low ventricular tachycardia (VT) detection rate because of a history of slow VT, increasing the VT detection rate was not feasible. After initiation of treatment with ivabradine, the sinus rate decreased and there was no recurrence of inappropriate shock during a 3-year follow-up period. Ivabradine was effective for preventing inappropriate shock due to sinus tachycardia.