Interference by antiarrhythmic agents with function of electrical cardiac devices

• Published in: Clinical pharmacy Vol. 11; no. 1; p. 48
• Main Authors: Tworek, D A, Nazari, J, Ezri, M, Bauman, J L
• Format: Journal Article
• Language: English
• Published: United States 01.01.1992
• Subjects: Anti-Arrhythmia Agents - therapeutic use; Atrial Fibrillation - prevention & control; Death, Sudden, Cardiac - prevention & control; Digoxin - therapeutic use; Drug Interactions; Electric Countershock; Female; Flecainide - therapeutic use; Humans; Male; Middle Aged; Pacemaker, Artificial; Prostheses and Implants; Verapamil - therapeutic use; Warfarin - therapeutic use
• ISSN: 0278-2677

The possible interference of drugs with the function of implanted electrical cardiac devices in two patients is described, and the literature on the interaction between these drugs and devices is reviewed. A 59-year-old woman had a permanent pacemaker implanted after diagnosis of tachycardia-bradycardia syndrome, and her drug regimen of digoxin, verapamil, and warfarin was supplemented with flecainide to prevent paroxysmal atrial fibrillation. A Holter monitor recording performed after five days of flecainide therapy showed the pacemaker was sensing and pacing normally. Approximately three weeks after pacemaker implantation and initiation of flecainide therapy, a Holter monitor recording showed high-grade atrioventricular block and failure of the pacemaker to capture. A chest roentgenogram showed that the pacemaker lead was properly placed. The pacemaker's pulse amplitude and pulse width were increased, and the device again functioned reliably. Six months later the pacing threshold was noted to have returned to normal. A 64-year-old man had a history of aborted sudden cardiac death from ventricular tachyarrhythmias. The patient received an automatic implanted cardioverter-defibrillator (AICD); at that time, a 15-J discharge was required to terminate induced ventricular fibrillation (VF). Three years later, the AICD was replaced; the energy required for VF termination with the new unit was 16 J. Seven months after implantation of the new unit, the patient had several episodes of ventricular tachycardia (VT). Moricizine therapy was initiated. An electrophysiologic study (EPS) three days later showed that a larger shock (28 J) was required to terminate VF and that the pacing threshold had increased.