P‐Wave Morphology: Underlying Mechanisms and Clinical Implications

Abstract

Increasing awareness of atrial fibrillation (AF) and its impact on public health revives interest in identification of noninvasive markers of predisposition to AF and ECG-based risk stratification. P-wave duration is generally accepted as the most reliable noninvasive marker of atrial conduction, and its prolongation has been associated with history of AF. However, patients with paroxysmal AF without structural heart disease may not have any impressive P-wave prolongation, thus suggesting that global conduction slowing is not an obligatory requirement for development of AF. P-wave morphology is therefore drawing increasing attention as it reflects the three-dimensional course of atrial depolarization propagation and detects local conduction disturbances. The factors that determine P-wave appearance include (1) the origin of the sinus rhythm that defines right atrial depolarization vector, (2) localization of left atrial breakthrough that defines left atrial depolarization vector, and (3) the shape and size of atrial chambers. However, it is often difficult to distinguish whether P-wave abnormalities are caused by atrial enlargement or interatrial conduction delay. Recent advances in endocardial mapping technologies have linked certain P-wave morphologies with interatrial conduction patterns and the function of major interatrial conduction routes. The value of P-wave morphology extends beyond cardiac arrhythmias associated with atrial conduction delay and can be used for prediction of clinical outcome of a wide range of cardiovascular disorders, including ischemic heart disease and congestive heart failure.

P-wave complexity in normal subjects and computer models

“…Incidental reports on nonfiltered averaged P waves have demonstrated complexity similar to our results [9], [10], [11], but this knowledge is not reflected in the recent medical literature. Not only textbooks, but also original reports show very smooth P waves [26], [27]. Using more recent technology and an approach targeted at precise alignment of P waves, we have confirmed the complex shapes shown in the older reports.…”

Prevalence and Prognostic Significance of Abnormal P Terminal Force in Lead V 1 of the ECG in the General Population

“…It has later been shown that the left atrial activation breakthrough site is reflected to a 12-lead ECG, and left atrial activation via the Bachmann bundle creates a P-wave with a terminal negative deflection in lead V 1 . 24 This atrial activation route has been shown to be prevalent in young patients with lone AF and is related to worse prognosis and development of AF in patients with ischemic heart disease. 25,26 A slightly abnormal PTF has been a relatively frequent finding also in studies conducted in normally healthy populations.…”

Prolonged QTc Interval Predicts Poststroke Paroxysmal Atrial Fibrillation

“…We have previously reported that a slow sinus heart rate on 24-hour ECG monitoring possibly helps predict PAF in patients with stroke. 38 It has also been reported that several other ECG parameters, including premature atrial beats, 39 P wave duration, 40 P wave morphology, 41 incomplete right bundle brunch block, 42 and left ventricular hypertrophy 43 are associated with silent PAF. These ECG factors might be comprehensively considered in a future study.…”