Association of P-Wave Duration, Dispersion, and Terminal Force in Relation to P-Wave Axis among Outpatients
Methods: We appraised our previously studied sample of 500 consecutively numbered, otherwise unselected, electrocardiograms (ECGs) of outpatients from the University of Massachusetts, Worcester, Massachusetts, for the foregoing P-wave characteristics. P-disp, defined as the difference of the duration between the widest and narrowest P wave, and the greatest P-dur after a 12-lead ECG search, was measured manually to the nearest 10 ms. PTFV1 was considered positive when ≥40 mm2 terminal deflection was present on biphasic P waves on lead V1. Normal P-axis was considered 0° to +75° by manually constructing the mean frontal plane electrical P-axis from standard limb leads.
Results: After excluding those with atrial arrhythmias, paced rhythms, errors in lead placement, P waves with low amplitude or overall technically poor tracing, 428 ECGs formed our final sample. P-dur was strongly associated with P-disp (P < 0.0001), but the correlation remained weak (r = 0.42). Overall, P-dur was not significantly associated with P-axis but when divided into tertiles and quintiles, the significance was evident within the range of the normal P-axis, particularly 0° to +60° (P < 0.0001). In a subanalysis of 380 ECGs that had appreciable biphasic P waves on lead V1, PTFV1 was noted on 178 (47%) ECGs and was significantly associated with P-dur (P < 0.0001), P-disp (P < 0.0001), and P-axis (P = 002). When considering P-axis in tertiles and quintiles, P-dur was greater in patients with a positive PTFV1 and significant within the normal range of the P-axis, especially from 0° to +60°.
Conclusion: P-dur, P-disp, and PTFV1 appear to share a significant tripartite association in relation to the normal P-axis, particularly when P-axis ranges 0° to +60°. Therefore, for optimal clinical assessment, these markers should be evaluated in relation to the normal P-axis.
Document Type: Research Article
Affiliations: 1: Department of Medicine, Saint Vincent Hospital, Worcester, MA 2: Division of Cardiology, Department of Medicine, St. Boniface General Hospital/University of Manitoba, Winnipeg, Manitoba, Canada 3: Division of Cardiovascular Medicine, Department of Medicine, University of Massachusetts Medical School, Worcester, MA
Publication date: July 1, 2007