P mitrale
Also callednotched P wave · bifid P wave · M-shaped P wave
Definition
P mitrale is the broad, notched (double-peaked, M-shaped) P wave in lead II, lasting 120 ms or more with its two peaks 40 ms or more apart, that is the classic surface-ECG marker of left atrial enlargement (left atrial abnormality). Left atrial activation normally begins and ends later than right atrial activation; when it is delayed further, the right- and left-atrial peaks, normally fused, separate and the P wave lengthens. P mitrale is an older name, later replaced by the term left atrial enlargement once it was realized that different clinical conditions cause similar P-wave changes.
Sources
- Hancock EW, Deal BJ, Mirvis DM, et al. AHA/ACCF/HRS recommendations for the standardization and interpretation of the electrocardiogram: part V: electrocardiogram changes associated with cardiac chamber hypertrophy. Circulation. 2009;119(10):e251-e261. doi.org/10.1161/CIRCULATIONAHA.108.191097
- Samesima N, God EG, Kruse JCL, et al. Brazilian Society of Cardiology guidelines on the analysis and issuance of electrocardiographic reports - 2022. Arq Bras Cardiol. 2022;119(4):638-680. doi.org/10.36660/abc.20220623
Last reviewed 2 October 2026. Every definition in the EKG Dictionary cites the guideline, consensus statement or original paper it comes from.