Usefulness of the Electrocardiographic P-Wave Axis as a Predictor of Atrial Fibrillation.

The association between abnormal electrocardiographic P-wave axis with atrial fibrillation (AF) has not been systematically studied in community-based populations. We examined the association between abnormal P-wave axis and AF in 4,274 participants (41% men and 95% white) from the Cardiovascular Health Study. Axis values between 0° and 75° were considered normal. AF cases were identified from study electrocardiograms and from hospitalization discharge data. During a median follow-up of 12.1 years, a total of 1,274 participants (30%) developed AF. The incidence rate of AF was 26 cases per 1,000 person-years for those with abnormal P-wave axis and 24 cases per 1,000 person-years for subjects with normal P-wave axis. Abnormal P-wave axis was associated with a 17% increased risk of AF (95% confidence interval 1.03 to 1.33) after adjustment for age, gender, race, education, income, smoking, diabetes, coronary heart disease, stroke, heart failure, heart rate, systolic blood pressure, body mass index, total cholesterol, high-density lipoprotein cholesterol, antihypertensive medications, aspirin, and statins. The results were consistent in subgroup analyses stratified by age, gender, and race. In conclusion, abnormal P-wave axis, a routinely reported electrocardiographic measurement, is associated with an increased risk of AF. This finding suggests a potential role for P-wave axis in AF risk assessment.