Systolic anterior motion of mitral valve leaflet following accessory pathway ablation in a patient without hypertrophic cardiomyopathy: a case report.

Background: Accessory pathway ablation is recommended for patients with symptomatic Wolff-Parkinson-White (WPW) syndrome. Although elimination of the accessory pathway restores normal ventricular activation and improves synchrony, it can occasionally cause systolic anterior motion (SAM) of the mitral valve leaflet, which can lead to functional left ventricular outflow tract (LVOT) obstruction. Case summary: We report a case of a patient admitted with WPW syndrome. After successful posteroseptal accessory pathway ablation, the patient developed exertional chest tightness and syncope. Echocardiography revealed significant SAM of the mitral valve leaflet and an elevated LVOT peak pressure gradient. Cardiac magnetic resonance confirmed a sigmoid-shaped interventricular septum and a small left ventricular cavity. Genetic testing excluded pathogenic mutations in genes associated with hypertrophic cardiomyopathy. Treatment with metoprolol alleviated his symptoms, with no recurrence of syncope. Follow-up echocardiography showed that the SAM of the mitral valve leaflet had been resolved. Conclusion: Although SAM of the mitral valve leaflet rarely occurs following accessory ablation, it could induce deleterious consequences. We hypothesized that the coexistence of a sigmoid septum and a small ventricular cavity may increase the risk for functional outflow tract obstruction after accessory pathway ablation.