[Increased Ventricular Pacing Threshold Caused by Intake of Dronedaron]. / Erhöhung der ventrikulären Reizschwelle durch Dronedaron-Einnahme.

HISTORY: The 75 year old patient was hospitalized because of vertigo, exertional dyspnea and clamminess. Based on ischemic heart disease with sick sinus syndrome a pacemaker was implanted 5.5 years ago. In consequence of non-permanent atrial fibrillation Dronedaron was added to medication 8 months ago. FINDINGS AND DIAGNOSIS: The patient presented unstable. The ECG showed a second-degree atrioventricular block with wenckebach periodic and a frequency of 29 bpm. The pacemaker survey showed primary a proper atrial function but ineffective ventricular stimulation. THERAPY AND COURSE: After initial external pacing the pacemaker was reprogrammed and in this way the ventricle stimulated effectively. Dronedaron was ceased after checking trigger factors and the patient left hospital after 3 days free of complaints. The pacemaker survey 18 days later showed a proper function with stabilized pacing threshold close to the old level. CONCLUSIONS: In patients with dysfunction of a permanent pacemaker an increased pacing threshold should be excluded and if any the current medication needs to be controlled. Caution should be exercised to Dronedaron here.