Severe mitral regurgitation with coexisting giant left atrium in a patient with Williams syndrome

A 31-year-old man, who had been diagnosed with Williams syndrome (WS) during childhood but had not been seen regularly in hospital, was urgently brought to our hospital because of nocturnal dyspnea and palpitations. His chest X-ray showed pulmonary congestion. His electrocardiogram revealed atrial fibrillation with tachycardia. After acute heart failure treatment, transthoracic echocardiography (TTE) showed mildly impaired left ventricular ejection fraction and a mitral regurgitation (MR) jet which circulates from the center and along the posterior wall of the enlarged left atrium (LA: left atrial volume index: 203 ml/m²) and is associated with mitral annulus dilatation (Fig. 1: Panels A and B, Videos 1–3). In the parasternal view of TTE, the posterior mitral annulus was displaced posteriorly to the LA side by a portion of the overhanging left ventricular posterior wall, with a concomitant loss of coaptation of the tip of posterior mitral leaflet (PML) with the anterior mitral leaflet, likely as hamstringing of the PML (Fig. 1: Panels A, Video 1). Transesophageal echocardiography showed slight thickening of the valve leaflets, an MR jet with greatly accelerated flow at A2-A3, and an MR jet between A2 and P2 (Fig. 1: Panels C and D, Videos 4 and 5). Multiple factors were considered possible mechanisms for MR, including valve leaflet thickening and pseudo-prolapse of the mitral leaflet. Cardiac catheterization showed no significant stenosis in the coronary arteries and elevated pulmonary artery wedge pressure with v-wave (Fig. 1: Panel E) and MR with Sellers classification IV (Video 6), suggesting severe MR. While the ascending aortic diameter was slightly smaller at 19 mm (Fig. 1: Panel F), there was no supraventricular aortic stenosis (SVAS). Subsequently, mitral valvuloplasty, left atrial appendage closure, and left atrial plication were performed. Intraoperative findings have been reported to show mild thickening of the mitral valve leaflets, but no obvious mitral valve prolapse, tendon rupture or tendon elongation.

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