P-wave characteristics and histological atrial abnormality

BackgroundFibro-fatty transformation is believed to be the leading cause of deteriorated atrial conduction; however, any direct assessment in relation to P-wave characteristics is lacking. We sought to assess P-wave morphology (PWM) and duration (PWD) in relation to histology of the atrial myocardium.ObjectiveAtrial specimens were collected from 11 patients who died from cardiovascular causes (7 men; median age 73 years).MethodsTissue samples were taken at the level of superior and inferior PVs, center of posterior left atrial wall, terminal crest (CT) and Bachmann's bundle (BB) for assessment of fibro-fatty tissue extent. Standard 12-lead ECGs in sinus rhythm recorded during hospital stay were used for manual assessment of P-wave. Partial interatrial block (pIAB) was defined as a prolonged (≥ 120 ms) and bimodal P-wave in any lead on 12-lead ECG.ResultsThe median PWD was 160 (120–200) ms. Fibrosis extent in CT highly correlated to PWD (r = 0.914, p < 0.001). The combination of fibrosis extent and fatty tissue in BB (16%, range 1%–41%), CT (18%, range 3%–47%) or superior PV (15%, range 6%–24%) correlated to PWD (r = 0.627, p = 0.039; r = 0.795, p = 0.003; and r = 0.668, p = 0.025, respectively). pIAB pattern was observed in 10 subjects; however, it was not associated with either fibrosis or fatty tissue content at any sampling location.ConclusionsOur findings further support causal association between PWD and the extent of structural abnormalities in the atrial myocardium and the major atrial conduction routes.