Morphological features of the P-waves at surface electrocardiogram as surrogate to mechanical function of the left atrium following a successful modified maze procedure.

Aims: Absent left atrium (LA) mechanical contraction may occur following the modified Cox-maze operation, and was found to impose a potential risk for the occurrence of thrombo-embolic stroke. It is unknown whether certain morphological P-wave characteristics can surrogate absent LA mechanical activity. The aim of this study was to evaluate the morphological features of the P-waves on the surface electrocardiogram (ECG) of patients who underwent the maze operation and to relate them to the contractile profile of the LA.
Methods and Results: Electrocardiogram tracings of 150 consecutive patients that were in sustained sinus rhythm following the maze operation were evaluated. P-waves were scrutinized for morphology, duration, axis, and amplitude. Clinical, surgery-related, and echocardiographic data were collected and analysed. Forty-seven patients (31%) had no evidence of LA contraction at 3 months after surgery (baseline assessment) and on follow-up echocardiography. Multivariate analysis showed that a positive-only P-wave deflection at lead V1 (P = 0.03), a negative-only deflection at aVL, and a P-wave amplitude of ≤ 0.05 mV at the septal-anterior leads (P < 0.001 for both) were associated with absent LA mechanical contraction. In a secondary analysis, a risk score involving the above three parameters was developed for the prediction of stroke occurrence. Patients at the high-risk score group had a 30% survival freedom of stroke compared with 70% for patients at intermediate risk (P < 0.001).
Conclusion: Absent LA mechanical contraction following the modified maze operation may be accompanied by a distinguished pattern of the P-waves on the surface ECG.