Prolonged repolarization in atrial septal defect: An example of mechanoelectrical feedback due to right ventricular volume overload.

BACKGROUND: Prolonged corrected QT (QTc) intervals are frequently observed in children before atrial septal defect (ASD) closure in our department.

OBJECTIVE: The aim of the study was to assess the effect of long-term right ventricular volume overload on repolarization.

METHODS: QRS, QT, and JT intervals were measured manually in leads II and V5 of a standard 12-lead electrocardiogram in 45 children with an isolated ASD a day before and at least 6 months after ASD closure. QT intervals were corrected for heart rate using the Bazett, Fridericia, Framingham, and Hodges formulas. Each QTc interval calculated using the Bazett formula was compared to sex- and age-matched normal values.

RESULTS: Individual QTc intervals shortened significantly (P < .001) using all correction formulas, whereas the QRS duration did not change. The prevalence of prolonged QTc interval decreased from 22.2% to 2.2% after shunt closure (P = .007).

CONCLUSION: The QTc interval shortens significantly after the closure of a hemodynamically relevant ASD in childhood. This phenomenon is independent of the used QT correction formula and may reflect a mechanoelectrical feedback associated with right ventricular volume overload.