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His-bundle ablation followed by pacemaker implantation is today a widely accepted therapeutic choice when drug refractoriness of symptomatic AF is evident. The selection of pacing mode in patients suffering from paroxysmal AF is still controversial. Preservation of AV synchrony is an attractive option in patients with paroxysmal AF who undergo His-bundle ablation. The purpose of this study was to examine prospectively the contribution of VDDR pacing for preservation of AV synchrony. After His-bundle ablation a VDDR pacing system was implanted in 17 patients with paroxysmal AF, and all antiarrhythmic drugs were withdrawn. The endpoint of the study was defined as the onset of chronic AF. To document the onset of chronic AF 48-hour Holter recordings were made every 6-8 weeks. After a mean followup of 18.2 (range 14-21) months, VDDR pacing is still operative in 13 patients (77%). Four patients developed chronic AF after a mean follow-up of 6 months. Of several baseline characteristics, only the intraatrial P wave at implantation was significantly smaller in patients developing chronic AF than in patients in whom the VDDR mode is still operative. This pilot study suggests that VDDR pacing is an attractive pacing method for patients with paroxysmal AF after His-bundle ablation. A low intraatrial P wave electrogram at implant was associated with a higher risk for the development of chronic AF.

A high dislodgment rate during long-term atrial pacing using the unipolar sickle-shaped active fixation lead was recently reported; therefore, the long-term results of atrial pacing in 118 consecutive patients with the bipolar sickle-shaped active fixation lead (Biotronik FH60-BP) were evaluated. Between January 1989 and September 1993, 87 leads (74%) were inserted for dual chamber pacing and 31 leads (26%) for atrial pacing only. At the time of implantation, the bipolar atrial electrogram had a mean voltage of 4.4 +/- 1.6 mV, whereas the acute atrial threshold was 0.72 +/- 0.38 V and 1.46 +/- 0.67 mA at 0.5-msec pulse duration and mean resistance 506 +/- 79 omega. Early lead dislodgment (< 1 month after implantation) occurred in 9 patients (7.6%). During a mean follow-up of 21.8 months (median 20.9 months), late dislodgment (> 1 month after implantation) occurred in 6 patients (5.1%) after a mean interval of 7.9 months (range 3-14 months). Due to the unacceptably high late dislodgment rate, which to date remains unexplained, new implants of this lead are not recommended.

To evaluate the feasibility of chronic atrial pacing (AAI) in sick sinus syndrome (SSS), 22 patients (pts) with bradytachycardia syndrome (BTS) and 17 patients with only bradyarrhythmias (BA) were studied on the incidence of supraventricular tachycardias (SVT) and occurring AV block. A scoring system based on symptoms of SVT was developed (grade 0-5). All patients had proven normal AV conduction before PM implantation. In the BTS-group, nine patients (41%) had symptomatic SVT at the end of follow-up (mean 53 months), despite drug therapy. These patients had a high SVT score on entry (mean 3.2). High degree AV block occurred in three patients. Although in the BA-group SVT arose in six patients (35%), there was only one symptomatic patient at the end of follow-up (mean 36 months). In this group, only one patient developed high degree AV block. Atrial stimulation should be considered as a reliable therapy in patients with SSS and low SVT score before PM implantation when normal AV conduction is present.