Notched P-Wave on Digital Electrocardiogram Predicts Cardiovascular Events in Patients with Cardiovascular Risks: The Japan Morning Surge Home Blood Pressure Study

Abstract

Background: The relationship between notched P-wave characteristics on digital electrocardiogram (ECG) and long-term cardiovascular events remains unclear. Methods: We enrolled 810 subjects from the Japan Morning Surge Home Blood Pressure study who had one or more cardiovascular risk factors. Twelve-lead electrocardiography was conducted, and the peak-to-peak distance in the M shape was calculated automatically using a 12-lead ECG analysis system. We compared two definitions: P-waves were defined as “notched” if the peak-to-peak distance in the M shape was ≥20 ms or ≥40 ms in lead II. We assessed the left atrial diameter and left ventricular mass index (LVMI) by echocardiography. The primary endpoint was defined as a composite endpoint that combines fatal events (stroke, heart failure, coronary artery disease, and sudden death) and nonfatal events (acute myocardial infarction, angina, congestive heart failure, stroke, and aortic dissection). Results: The mean follow-up period was 101 ± 34 months, during which 85 cardiovascular events occurred. When we defined a notched P-wave as ≥20 ms in the M shape (n = 92), a notched P-wave was a significant predictor of cardiovascular events after adjustment for age, gender, and comorbidity (hazard ratio: 1.83; 95% confidence interval: 1.01–3.31, p = 0.045). When we defined a notched P-wave as ≥40 ms in the M shape (n = 25), the hazard ratio of cardiovascular events in the notched P-wave group was not significant after adjustment for covariates (hazard ratio: 1.52; 95% confidence interval: 0.51–4.53, p = 0.455). The left atrial diameter and LVMI in the patients in the notched P-wave group (peak-to-peak distance of ≥20 ms in the M shape) were significantly higher than those in the control group (left atrial diameter: 38.8 ± 5.9 vs. 36.8 ± 5.0 mm, p = 0.001; LVMI: 103.9 ± 27.7 vs. 96.3 ± 25.7 g/m2, p = 0.010). Conclusions: The notched P-wave by digital ECG analysis was associated with cardiovascular events and left atrial enlargement.