[Increased Ventricular Pacing Threshold Caused by Intake of Dronedaron]

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.

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.

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.

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.