Ectopic atrial rhythm after superior septal approach to the mitral valve - an often under-reported entity.

Purpose: Very few reports elaborate on the changes in P wave following superior septal approach to the mitral valve. We aimed to describe the changes in the P wave axis and other electrocardiographic changes following this approach among patients preoperatively in sinus rhythm.

Methods: We did a retrospective review of medical records among all our patients undergoing superior septal approach for mitral valve surgery from September 2014 to September 2019. Electrocardiograms during hospital stay and until 6-month follow-up were analyzed. A deviation in P wave axis from the normal range of + 30 to + 60° was classified as ectopic atrial rhythm.

Results: In the study population of 47 patients (age 16-75 years, 51.3 ± 13.6 years; M:F ratio 3.7:1), who were in normal sinus rhythm preoperatively, 34 patients (72.3%) had a visible P wave on electrocardiogram (ECG) at discharge. Among them, the P wave axes of 17 patients (36.2%) were within normal range (normal sinus rhythm), whereas 17 patients (36.2%) had ectopic atrial rhythm at discharge. The most frequent abnormal P wave axis was between 0 and - 30° (12 patients). At 6 months, 8 patients (17.0%) had a persistent ectopic atrial rhythm. These patients underwent a Holter test at 6 months and were followed up for symptomatic bradycardia for 3 years. None of the patients with ectopic atrial rhythm required pacemaker insertion.

Conclusion: Persistence of ectopic atrial rhythm at 6 months is common (17%) after superior septal approach. Documentation of P wave axis after this approach will help avoid missing it. These patients may be kept on follow-up to look for symptomatic bradycardia.