PREDICTIVE VALUE OF THE P-WAVE AT IMPLANTATION FOR ATRIAL-FIBRILLATION AFTER VVI PACEMAKER IMPLANTATION

This study assesses the value of P wave measurements on the surface ECG at implantation, in the prediction of atrial fibrillation in VVI paced patients. From a consecutive series of 320 pacemaker implantations 172 VVI paced patients for symptomatic atrioventricular block (AVB) (n = 126; mean age 69 +/- 14) or sick sinus syndrome (SSS) (n = 56; mean age 68.6 +/- 12) and in sinus rhythm at implantation were used in this study. P wave duration in VI is correlated with the incidence of atrial fibrillation during 5 years of follow-up. VI at implantation was significantly longer (1 14.6 +/- 2.7 msec) in the patients who developed atrial fibrillation than in those who did not (91.9 +/- 2.7 msec) (P < 0.001). Although positive predictive accuracy increases progressively for higher V1 values for AVB and SSS, the negative predictive and diagnostic accuracy of V1 criteria were less in SSS. Application of the Bayes' theorem showed that in SSS the probability to develop atrial fibrillation is 33% for V1 < 110 msec and is for V1 < 90 msec still higher than that reported in DDD paced patients. In the AVB group the probability to develop atrial fibrillation is 8% for V1 < 110 msec and 6% for V1 < 100 msec. It seems, therefore, that atrial stimulation (AAI or DDD) is always indicated in SSS. In AVB with V1 < 100 msec, DDD pacing, if not needed for other indications, apparently does not offer much benefit in the prophylaxis of atrial fibrillation.