P-wave signal averaged ECG: reference values, clinical correlates, and heritability in the Framingham Heart Study.

Abstract Background P-wave signal-averaged electrocardiography (P-SAECG) quantifies atrial electrical activity. P-SAECG measures and their clinical correlates and heritability have had limited characterization in community-based cohorts. Objectives To 1) Establish reference values; 2) Identify clinical risk factors associated with P-SAECG; and 3) Estimate genetic heritability for P-SAECG traits. Methods We performed P-SAECG in two generations of Framingham Heart Study participants. We performed backward elimination regression models to assess associations of clinical factors with each SAECG trait (P-wave (PW) duration, Root Mean Square Voltage in terminal 40 ms (RMS40), RMS30, RMS20, RMS PW, and PW integral). We estimated the adjusted genetic heritability of P-SAECG measures using the SOLAR program. Results We included 4307 participants (age 55±14 years, 56% female). The reference values were derived from 1752 participants without cardiovascular risk factors. The median (2.5th percentile; 97.5th percentile) total PW duration was 118ms (93;146) in women, and 128ms (104;158) in men in the reference sample, and 121ms (94;151) in women and 129ms (103;159) in the entire study cohort (broad sample). In the broad sample, after adjusting for age and sex, total PW duration was positively associated with height, weight, prevalent heart failure, history of AF, and AV-node blockers, and negatively associated with smoking, waist circumference, heart rate, and diabetes. The estimated heritability of P-SAECG traits was moderate, ranging from 11.9% for RMS30 to 24.9% for PW integral. Conclusion P-SAECG traits are associated with multiple AF-related risk factors and are moderately heritable.