EFFICACY OF DIFFERENT PACING MODES IN PATIENTS WITH INTACT SINUS NODEFUNCTION WHO UNDERWENT RF AV JUNCTION ABLATION DUE TO DRUG-REFRACTORYPAROXYSMAL ATRIAL-FIBRILLATION

Previous studies have demonstrated that in patients (pts) with drug re fractory paroxysmal atrial fibrillation (AF) and intact sinus node, RF AV junctional ablation and permanent pacemaker implantation is an alt ernative therapy with excellent long term results in terms of arrhythm ia control and quality of life. A very important factor is the selecti on of the pacing mode. The efficacy of automatic mode switch (AMS) to control the ventricular rate during episodes of paroxysmal AF has been reported. Aim of this study was to evaluate the long term arrhythmia behavior under 2 different pacing modes, DDD-R and VDD/VVI-R, both wit h the option of AMS, in pts with drug refractory paroxysmal AF, intact : sinus node and complete AV block due to RF AV junction ablation. We evaluated 16 pts (10M, 6F), without structural heart disease, mean age 60+/- 5 years with paroxysmal AF intact sinus node and AV junction ab lation. The previous failed antiarrhythmic drugs were 3.3+/- 2. The du ration of symptoms was 5.2+/- 2.9 years at a maximal heart rate 162+/- 20 bpm. The hospital admissions in the last 12 months were 6.5+/- 3 p er pt. In all pts a DDD-R with AMS was implanted (Medtronic Thera DR). Each pt was evaluated during a 6 month period under DDD-R and an equa l time period under VDD/VVI-R pacing mode which was randomly selected. Using the Holter function of the device, we measured the recorded epi sodes and duration of PBF and the proportion of atrial sensing- ventri cular pacing (As-Vp), atrial-ventricular pacing (Ap-Vp) and VVI pacing (Vp). We compared these parameters for the 2 different pacing periods . The paroxysmal AF episodes recorded under DDD-R were 20+/- 9.7 and u nder VDD/VVI-R 22.8+/- 11 (p=0.03). The duration of paroxysmal AF was 95.5+/- 59.8min under DDD-R and 105.8+/- 54.5min under VDD/VVI-R (p=0. 02). The proportion of As-Vp was similar (p=NS) in both pacing modes ( DDD-R 87.8+/- 4%, VDD/VVI-R 90.5+/- 3%). The remaining proportion of p acing was Ap-Vp for the DDD-R (12.2+/- 4%) and Vp for the VDD/VVI-R (9 .5+/- 2%) (p=NS). In conclusion, pts with drug refractory paroxysmal A F, intact sinus node, AV junction ablation and permanent pacemaker imp lantation the DDD-R pacing is more efficient in terms of arrhythmia re currence in comparison to VDD/VVI-R. It seems that atrial pacing may b e a stabilizing factor in pts with paroxysmal AF even if they have int act sinus node function.