Electrocardiographic P-wave indices and onset of atrial fibrillation and histological fibrosis in a general Japanese population: a prospective cohort analysis of the Hisayama Study

Aims P-wave indices (PWIs) are associated with incidence of atrial fibrillation (AF) and extent of left atrial fibrosis. We investigated associations of P-wave duration and P-wave terminal force in V1 (PTFV1) with incidence of AF and extent of atrial fibrosis in a Japanese community. Methods Participants were classified based on P-wave duration in lead II (≥120 and <120 ms) or PTFV1 (≥4000 and <4000 μV*ms). Fibrosis in the left atrial posterior wall was pathologically evaluated in 133 autopsied cases with clinical information. Hazard ratios for AF were estimated using a Cox proportional hazards model. Differences in the extent of left atrial fibrosis between P-wave index categories were tested by analysis of covariance. Results A total of 2,907 community-dwelling individuals aged ≥40 years without prior AF were followed for 10 years. Participants with prolonged P-wave duration or elevated PTFV1 were older and had more cardiovascular risk factors. During follow-up, 140 participants developed AF. Unadjusted incidence rates of AF were significantly higher in participants with P-wave duration ≥120 ms or PTFV1 ≥4000 μV*ms than in those with values below these cutoffs (4.6 vs. 10.6, and 4.7 vs. 14.4 per 1,000 person-years, respectively; both p<0.001). Participants with P-wave duration ≥120 ms had a significantly higher age- and sex-adjusted geometric mean percentage of left atrial fibrosis than those with P-wave duration <120 ms (p=0.04). Conclusion P-wave duration and PTFV1 are useful indicators for assessing AF risk. Furthermore, prolonged P-wave duration reflects the extent of left atrial fibrosis.