Clinical significance of a new P wave lead vector for pacemaker follow-up of atrial functions

Patient welfare requires routine follow-up procedures of implantable pacemakers. However, the assessment of atrial sensing and pacing functions in implantable pacemakers is often a challenge due to difficult identification of low amplitude P waves on surface electrocardiograms (ECGs). A previous body surface mapping study suggested that a novel P wave lead vector (P lead) had larger root mean square values than other standard leads. However, for pacemaker follow-up procedures, peak-to-peak amplitudes are more relevant than root mean square values. In this study, the peak-to-peak amplitudes of intrinsic and paced P waves recorded from surface ECG standard lead II and the P lead were compared. In addition, intrinsic and paced R waves were also compared. Data recorded from 15 patients undergoing electrophysiological studies indicated that peak-to-peak amplitudes of the P lead were significantly larger than standard lead II: 24% for intrinsic P waves, 30% for paced P waves, and 72% for intrinsic R waves. In addition, the P lead amplitude of paced R waves showed a nonsignificant increase of 24% compared with standard lead II. Therefore, the use of this new lead vector may improve the clinical ease-of-use and reduce the time required for follow-up procedures of implantable pacemakers for atrial sensing and pacing assessments.