Myocardial bridges as a cause of persistent repolarization disturbances in children after radiofrequency ablation of Wolff – Parkinson – White syndrome / phenomenon: a case series and diagnostic algorithm

Background. Radiofrequency catheter ablation (RFCA) is the method of choice for treating patients with Wolff – Parkinson – White (WPW) syndrome. The disappearance of the delta wave is usually accompanied by the normalization of secondary repolarization abnormalities (ST-T segment changes). Persistent repolarization abnormalities after successful RFCA require investigation for other causes, such as myocardial ischemia.

Aim: To assess the potential role of myocardial bridges in the persistent repolarization abnormalities after successful radiofrequency ablation of accessory atrioventricular pathways (AAVPs) in children with WPW syndrome, using a case series, and to propose a diagnostic algorithm.

Material and Methods. We retrospectively analyzed five pediatric patients aged 8 to 17 years with WPW syndrome (n = 4) and a nodal-ventricular tract (n = 1). All patients presented persistent ST-segment depression on ECG after ablation (and at baseline in the non-ablated patient with a nodal-ventricular tract). All patients underwent a comprehensive non-invasive workup to exclude other causes of ST-segment changes, including exercise stress testing, stress echocardiography or myocardial perfusion scintigraphy, and ultimately, multislice computed tomography (MSCT)-coronary angiography (CAG).

Results. Coronary artery anomalies were identified in all five cases by MSCT-CAG: one case with anomalous origin of the right coronary artery from the left sinus of Valsalva, and four cases with myocardial bridges (MBs) (three cases involving the left anterior descending artery). Despite significant ischemic ECG changes (ST-depression up to 3.5 mm, positive exercise tests in 3/4), functional imaging (scintigraphy, stress Echo) showed no perfusion defects or wall motion abnormalities. Symptomatic patients (n = 3) were treated with a beta-blocker (bisoprolol) with symptomatic improvement in one; one patient with an anomalous coronary origin underwent surgical correction.

Conclusion. Myocardial bridges are an under-recognized cause of persistent repolarization abnormalities in children with WPW after successful RFCA. A diagnostic mismatch (positive ECG and exercise stress test findings, but negative functional imaging with MPS and stress Echo) should raise suspicion for dynamic ischemia induced by MBs. Including MSCT-CAG in the diagnostic algorithm for such patients enables accurate diagnosis and guides appropriate therapy.

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