Interatrial conduction can be accurately determined using standard 12-lead electrocardiography: validation of P-wave...

Different P-wave morphologies during sinus rhythm as displayed on standard ECGs have been postulated to correspond to differences in interatrial conduction.

The purpose of this study was to evaluate the hypothesis by comparing P-wave morphologies using left atrial activation maps.

Twenty-eight patients (mean age 49 +/- 9 years) admitted for ablation of paroxysmal atrial fibrillation were studied. Electroanatomic mapping of left atrial activation was performed at baseline during sinus rhythm with simultaneous recording of standard 12-lead ECG. Unfiltered signal-averaged P waves were analyzed to determine orthogonal P-wave morphology. The morphology was subsequently classified into one of three predefined types. All analyses were blinded.

The primary left atrial breakthrough site was the fossa ovalis in 8 patients, Bachmann bundle in 18, and coronary sinus in 2. Type 1 P-wave morphology was observed in 9 patients, type 2 in 17, and type 3 in 2. Seven of eight patients with fossa ovalis breakthrough had type 1 P-wave morphology, 16 of 18 patients with Bachmann bundle breakthrough had type 2 morphology, and both patients with coronary sinus breakthrough had type 3 P-wave morphology. Overall, P-wave morphology criteria correctly identified the site of left atrial breakthrough in 25 (89%) of 28 patients.

In the vast majority of patients, P-wave morphology derived from standard 12-lead ECG can be used to correctly identify the left atrial breakthrough site and the corresponding route of interatrial conduction.