Incidence and predictors of new onset atrial fibrillation after single chamber VVI pacemaker implantation in patients with normal baseline cardiac function

Background: Atrial fibrillation is a relatively common arrhythmia often seen in patients with permanent pacemakers. In patients with underlying left ventricular dysfunction, single chamber right ventricular pacing increases the incidence of heart failure and atrial fibrillation [1]. But, in patients with normal baseline cardiac function, these effects are not clearly defined. Therefore, with this background in mind we aimed to assess the incidence, predictors and time frame of appearance of new onset atrial fibrillation in patients with normal baseline cardiac function who underwent single chamber VVI pacemaker implantation. Material and Methods: All consecutive patients undergoing VVI pacemaker implantation under the free pacemaker scheme of the State Government, in the Department of Cardiology, Gauhati Medical College and having ACC-AHA Class I indication for PPI and normal cardiac function at baseline were included in the study from September 2010 to August 2011. Each patient was followed up for one year till September 2012. Patients with any form of underlying structural heart disease, ventricular dysfunction, CKD, COPD or any other pacing mode were excluded from the study. They were followed prospectively by echocardiography (left atrial dimension) and ECG which were done at baseline, 1 week, 1 month, 3 months, 6 months and 12 months after implantation till July, 2012. Changes in left atrial dimensions and any documented new onset atrial fibrillation were noted during the follow up period and its time frame of appearance were recorded. At 12 months pacemaker interrogation was done to look for percentage cumulative ventricular pacing. Results : One hundred fifty five (155) consecutive patients with mean age 61±12 (Range 27 87), 80.6% males, mean left ventricular Ejection Fraction of 63.59±4.87% (55.7 – 78.0) who undergone VVI pacemaker implantation were enrolled in this study. New onset persistent atrial fibrillation was found in fifteen patients (9.7%). Significant increase in mean left atrial end-diastolic diameter (LAd) was observed as early as 1 month (from 26.72 ± 3.83 mm at baseline to 28.65 ± 2.8 mm at 1 month, p<0.001). Cumulative ventricular pacing percentage was found to be strongly associated with new onset AF. Conclusion: Single chamber VVI pacing in patients with normal baseline cardiac function was associated with 9.7% incidence of new onset atrial fibrillation between 6 to 12 months after implantation. Progressive increase in mean left atrial end-diastolic diameter with LA diastolic dimension > 40 mm and higher percentage of paced beats were strong predictors of new onset atrial fibrillation in our study.