Orthogonal P-wave morphology, conventional P-wave indices, and the risk of atrial fibrillation in the general population using data from the Finnish Hospital Discharge Register

Aims Identifying subjects at high and low risk of atrial fibrillation (AF) is of interest. This study aims to assess the risk of AF associated with electrocardiographic (ECG) markers linked to atrial fibrosis: P-wave prolongation, 3rd-degree interatrial block, P-terminal force in lead V-1, and orthogonal P-wave morphology. Methods and results P-wave parameters were assessed in a representative Finnish population sample aged >= 30 years (n= 7217, 46.0% male, mean age 51.4 years). Subjects (n=5489) with a readable ECG including the orthogonal leads, sinus rhythm, and a predefined orthogonal P-wave morphology type [positive in leads X and Y and either negative (Type 1) or +/- biphasic (Type 2) in lead Z; Type 3 defined as positive in lead X and +/- biphasic in lead Y], were followed 10 years from the baseline examinations (performed 1978-80). Subjects discharged with AF diagnosis after any-cause hospitalization (n=124) were defined as having developed AF. Third-degree interatrial block was defined as P-wave >= 120 ms and the presence of >= 2 +/- biphasic P waves in the inferior leads. Hazard ratios (HRs) and confidence intervals (Os) were assessed with Cox models. Third-degree interatrial block (n = 103, HR 3.18, 95% CI 1.66-6.13; P = 0.001) and Type 3 morphology (n = 216, HR 3.01, 95% CI 1.66-5.45; P < 0.001) were independently associated with the risk of hospitalization with AF. Subjects with P-wave <110 ms and Type 1 morphology (n = 2074) were at low risk (HR 0.46, 95% CI 0.26-0.83; P = 0.006), compared to the rest of the subjects. Conclusion P-wave parameters associate with the risk of hospitalization with AF.