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Williams syndrome (WS) is a congenital, developmental disorder affecting 1 in 8,000 live births. The corrected QT (QTc) interval is prolonged in 13% of patients with WS. No data exist characterizing the ambulatory electrocardiographic findings in WS. A retrospective review of all patients with WS evaluated at our institution from January 1, 1980 to December 31, 2007 was performed. Patients with ≥1 ambulatory electrocardiogram (AECG) with sinus rhythm and measurable intervals were included. QTc measurements were made at the minimum and maximum heart rate. Logistic regression analysis was used to evaluate the correlation of ventricular ectopic complexes with QTc measurements. A statistical probability of p <0.05 was considered significant. Of 270 patients identified, 32 had AECGs available for review. Complete data were available for 56 AECGs from 26 patients (15 female; 58%). Their mean age was 15.6 ± 7.2 years at the initial AECG and 20.6 ± 8.6 years for all AECGs. The QTc interval increased with increasing heart rate. Ventricular premature complexes occurred in 40 (73%) of 56 AECGs and 21 (81%) of 26 patients. Ventricular tachycardia occurred in 5 (9%) of 56 AECGs and 4 (15%) of 26 patients. The mean length of ventricular tachycardia was 3.6 ± 0.5 beats at a rate of 171 ± 40 beats/min. The QTc interval at the minimum heart rate correlated directly with age (p <0.001), total ventricular premature complexes (p = 0.007), ventricular couplets (p = 0.002), and ventricular tachycardia (p = 0.011). The QTc interval at the maximum heart rate correlated directly with age (p <0.001), total ventricular premature complexes (p = 0.016), and ventricular couplets (p = 0.006). In conclusion, the QTc interval correlated with ventricular ectopic complexes in patients with WS. The type of ventricular ectopic complexes suggested an alternate etiology of the QTc prolongation seen in WS from that seen in congenital long QT syndrome. [Copyright &y& Elsevier]

Williams syndrome (WS) affects 1 in 8,000 live births and has a high risk of sudden death. No previous studies have evaluated corrected QT (QTc) prolongation in WS. Retrospective review of all patients with WS evaluated at our institution from January 1, 1980 to December 31, 2007 was performed. WS was diagnosed by a medical geneticist and/or by fluorescence in situ hybridization. Patients with ≥1 electrocardiogram (ECG) with sinus rhythm and measurable intervals were included. Normal control ECGs were identified from a large clinical database. Corrected JT (JTc) interval was calculated when QRS and QTc intervals were prolonged. QTc interval ≥460 ms and JTc interval >340 ms were defined as prolonged. Prevalence comparisons were made using Fisher''s exact test. Statistical probability of <0.05 was considered significant. Of 270 patients identified, 188 had ECGs for review. Complete data were present in 499 of 517 ECGs (patients'' mean age 10.3 ± 9.9 years); 1,522 normal ECGs of age-similar patients composed the control group. QTc prolongation prevalences were 2.0% in controls and 13.6% in WS (p <0.0001); in those, JTc prolongation prevalences were 1.8% in controls and 11.7% in WS (p <0.0001). Four patients died during follow-up; 2 had QTc prolongation and 1 died during noncardiac surgery. Another patient with QTc prolongation sustained cardiac arrest during a procedure. In conclusion, cardiac repolarization is prolonged in WS. Presence of prolonged cardiac repolarization may contribute to the high incidence of periprocedural mortality in these patients. All patients with WS should be screened for cardiac repolarization abnormalities, especially before surgery. [Copyright &y& Elsevier]

Williams syndrome (WS) is a congenital disorder affecting the vascular, connective tissue, and central nervous systems of 1 in 8,000 live births. Previous reports have reported high frequencies of cardiovascular abnormalities (CVAs) in small numbers of patients with WS. A retrospective review was undertaken of patients with WS evaluated at our institution from January 1, 1980 through December 31, 2007. WS was diagnosed by an experienced medical geneticist and/or by fluorescence in situ hybridization. CVAs were diagnosed using echocardiography, cardiac catheterization, or computed tomographic angiography. Freedom from intervention was determined using Kaplan-Meier analysis. The study group was 270 patients with WS. The age at presentation was 3.3 ± 5.9 years with follow-up of 8.9 ± 9.0 years (range 0 to 56.9). CVAs were present in 82% of the patients. The most common lesions were supravalvar aortic stenosis in 45% and peripheral pulmonary stenosis in 37%; 20% had both. Other common lesions included mitral valve prolapse and regurgitation in 15%, ventricular septal defect in 13%, and supravalvar pulmonary stenosis in 12%. Surgical or catheter-based interventions were performed in 21%. The rate of freedom from intervention was 91%, 81%, 78%, 72%, and 62% at 1, 5, 10, 20, and 40 years. Eight patients died. In conclusion, CVAs are common in patients with WS, but supravalvar aortic stenosis and peripheral pulmonary stenosis occurred less frequently in this large cohort than previously reported. In patients with WS and CVAs, interventions are common and usually occur by 5 years of age. Most patients with WS do not require intervention during long-term follow-up, and the overall mortality has been low. [Copyright &y& Elsevier]