Influence Of Pacing Therapy On The Incidence Of Atrial Fibrillation

Part One: Influence of different pacing modalities on the incidence of atrial fibrillation in patients with sick sinus syndromeObjective: A randomized trial was done to compare the influence of single- chamber atrial (AAI) and dual-chamber (DDD) pacing in patients with sick sinus syndrome ( SSS) and normal atrioventricular(AV)conduction, including the incidence of atrial fibrillation, changes of cardiac function and cardiac size.Methods: Patients with SSS who were implanted with pacemakers from January 1999 to December 2005 were enrolled. A Total of 133 consecutive patients were randomized to treatment with one of modes of pacemaker:AAI (n=45) or DDD (n=88).Patients were followed up after one month , three months, six months, and then once a year.The follow-up visits included patients'symptoms, physical examination, electrocardiogram (ECG) recording/or Holter recording ,echocardiography, New York Heart Association (NYHA) cardiac function class and pacemaker check-up.The primary end point was the incidence of atrial fibrillation. The second end points were New York Heart Association(NYHA) cardiac function class, changes in left atrial(LA) and left ventricular end-diastolic(LVED)diameters, as well as left ventricular ejection fraction (LVEF)measured by echocardiography.Result: Mean follow-up was 12～85(32.4±15.2) months.(1)Atrial fibrillation was significantly less common in the AAI group than in DDD group (11.1% vs 27.3%, P < 0.05). (2)In the AAI group, no significant changes were observed in LA diameter or LVED diameter or LVEF from baseline to last follow-up(P>0.05);In the DDD group,LA diameter and LVED diameter increased significantly(P<0.05), and LVEF decreased significantly from baseline to last follow-up (P<0.05);There was statistical difference in these values between AAI and DDD group (P<0.05) at last follow-up. (3)Compared with DDD group, AAI group have less effect on cardiac function.Conclusion: In patients with sick sinus syndrome and normal atrioventricular conduction, AAI pacing mode is more physiological than DDD pacing mode,with less incidence of atrial fibrillation and accepted cardiac function.Part Two: The clinical effect of atrial pacing algorithms on prevention and treatment of paroxysmal atrial fibrillationObjective: To evaluate the clinical effect of atrial pacing algorithms on prevention and treatment of paroxysmal atrial fibrillation (PAF).Methods: Twelve patients with sick sinus syndrome and paroxysmal atrial fibrillation were implanted with Vitatron Selection 900E(AF2.0,DDDR) pacemaker, the method of implantation is as same as the general double chamber pacemakers.After implantation patients were followed up every month to compare the numbers of PAF episodes stored, AF total duration, AF burden and atrial pacing rate in the monitoring phase and preventive pacing phase.Result: Except for one patient, the median number of PAF episodes stored [80(25;215),57(12;102)vs203(86;425)], the median AF total duration [1.9d(0.6d;5.3d), 1.5d(0.3d;6.1d)vs2.9d(0.8d;9.8d)]and the median AF burden [6.3%(2.0%;17.7%), 5.0% (1.0%;20.6%)vs9.6%(2.7%;32.8% )]of other patients were significantly decreased in the second month and the sixth month after implantation (preventive pacing phase) compared with those in the first month after implantation(monitoring phase) (P all<0.05), atrial pacing rate [60%(40%;80%), 54%(42%;84%)vs46%(26%;54%)]was significantly increased (P<0.05).Conclusion: Atrial-based preventive algorithms can decrease the number of PAF episodes and AF burden, as well as reduce symptoms.It has short-term therapeutic effect.