Temporary resolution of chronic atrial fibrillation after cardiac surgery and the prolongation of ventricular repolarization.

BACKGROUND

Chronic atrial fibrillation may temporarily resolve after cardiac surgery. Prolongation of the ventricular repolarization period may be the electrophysiological background for this phenomenon.

OBJECTIVES

The aim of the study was to assess the association between resolution of atrial fibrillation and changes in the duration of the ventricular repolarization period in patients with pre-operative chronic atrial fibrillation who underwent cardiac surgery.

MATERIAL AND

METHODS

A retrospective analysis of the medical recordings of patients with chronic atrial fibrillation who underwent cardiac surgery was performed. After exclusions the study group comprised 51 patients with chronic atrial fibrillation who underwent surgery in the Cardiac Surgery Department of Wrocław Medical University in 2008 and 2009. The 12-lead EKGs performed before and after the surgery were assessed and the QT and R-R intervals were measured. The patients were divided into Group 1, in whom atrial fibrillation persisted after the cardiac surgery, and Group 2, whose atrial fibrillation resolved after the surgery.

RESULTS

In 31 patients (60.8%) atrial fibrillation disappeared during the first 24 hours after cardiac surgery. A significant prolongation of the QT interval after the surgery was found in Group 2 that was not observed in Group 1. Multiple regression analysis revealed that QT interval duration after surgery is related to the resolution of atrial fibrillation independently from the duration of the R-R interval duration and the need for cardiac pacing.

CONCLUSIONS

Spontaneous temporary resolution of atrial fibrillation is a common finding after cardiac surgery in patients with chronic atrial fibrillation. This phenomenon is related to a prolonged QT interval, therefore it may have an electrophysiological basis rather than a hemodynamic background. Further studies are required to assess the clinical importance of the prolongation of the QT interval after cardiac surgery.