Frequency of QTc Interval Prolongation in Children and Adults with Williams Syndrome

Feasibility and findings of electrocardiogram recording in older adults with intellectual disabilities: results of the Healthy Ageing and Intellectual Disabilities study

BACKGROUND

Older adults with intellectual disabilities (ID) have a high risk of cardiovascular diseases (CVD). At the same time, challenging diagnostic work-up increases the likelihood of underdiagnosis of CVD in this population. To limit this underdiagnosis, it would be beneficial to use objective measures such as the electrocardiogram (ECG). However, little is known about the feasibility of ECG recording and the prevalence of ECG abnormalities in this population. Therefore, the aims of this study were to investigate the feasibility of resting ECG recording, to study the prevalence of ECG abnormalities, and to compare the frequency of ECG abnormalities with medical records in older adults with ID.

METHOD

A cross-sectional study was performed within a cohort of older adults (≥60 years) with ID as part of the Healthy Ageing and Intellectual Disabilities (HA-ID) study. A resting 12-lead ECG was attempted, and the ECG recording was considered feasible if the recording could be made and if the ECG could be interpreted by a cardiologist and the Modular ECG Analysis System (MEANS). ECGs were assessed for the presence of ECG abnormalities and medical record review was performed. If the cardiologist or MEANS concluded that there was evidence of myocardial infarction, atrial fibrillation or QTc prolongation on the ECG in the absence of this ECG diagnosis in the participant's medical record, this was classified as a previously undiagnosed ECG diagnosis.

RESULTS

ECG recording was feasible in 134 of the 200 participants (67.0%). Of these 134 participants (70.6 ± 5.8 years; 52.2% female), 103 (76.9%) had one or more ECG abnormality, with the most prevalent being prolonged P-wave duration (27.6%), QTc prolongation (18.7%), minor T-wave abnormalities (17.9%), first degree atrioventricular block (12.7%) and myocardial infarction (6.7%). Eight out of 9 (88.9%) myocardial infarctions and all cases of (significant) QTc prolongation (100%) were previously undiagnosed.

CONCLUSIONS

This study showed that ECG recording is feasible in the majority of older adults with ID and revealed a substantial underdiagnosis of ECG abnormalities. These results stress the importance of ECG recording and warrant further research into the yield of opportunistic ECG screening in older adults with ID.

A case of Williams syndrome with Wolff-Parkinson-White syndrome

INTRODUCTION

Williams syndrome (WS) cases have been reported to have with 25-100 times greater increased risk of sudden cardiac death (SCD). SCD has been reported in cases without any evidence of structural cardiovascular anomalies. Wolff-Parkinson-White (WPW) syndrome is characterized by short PR interval and delta wave. Ventricular preexcitations can develop paroxysmal reentrant tachycardia through Kent bundle or less frequent atrial fibrillation and in some cases with accessory pathway effective refractory period (APERP) under 250 ms considered as risky and may lead to SCD. WS associated with WPW has not been reported before.

CASE REPORT

An 11-year-old male who had been followed up with WS was referred to pediatric cardiology outpatient clinic with the complaint of palpitation. Electrocardiographic examination showed short PR interval and delta wave in the ECG consistent with WPW. He underwent electrophysiological study (EPS). Basic measurements were performed, and APERP was found at 280 ms cycle atrial pacing. RF energy was delivered using a 4 mm tip nonirrigated radiofrequency (RF) ablation catheter where the best ventriculoatrial (VA) signals were received and the AP was abolished within few seconds.

DISCUSSION AND CONCLUSIONS

Although, WPW cases are usually asymptomatic or related to SVT, the risk of SCD should not be ignored. Thus, all patients with WPW deserve an EPS for assessing the AP conduction properties. Due to the increased risk of SCD in patients with WS compared to general population, in the presence of concomitant WPW, these patients should be evaluated with EPS even if they do not have symptoms.

Arrhythmias in Williams Syndrome

Williams syndrome (WS) is a congenital, multisystem disorder in which 80% of patients have cardiovascular abnormalities. Sudden cardiac death occurs 25 to 100 times more often in WS than in the general population, and cardiac repolarization is abnormal in WS. We sought to determine the prevalence of primary arrhythmias in patients with WS and whether QTc prolongation impacts arrhythmia risk. We retrospectively reviewed all patients with WS with ambulatory electrocardiogram (ECG) monitoring at our institution between October 2017 and January 2022. The primary outcome was the presence of arrhythmia. Predictors pre-determined for analysis included premature ventricular and atrial complex burden (%), degree of QTc change with varying heart rates, intervals and rhythm on 12-lead ECG, age, gender, symptomatology, and clinical and surgical history. A total of 74 patients (55% female, median age 8 years (3, 13) underwent 108 ambulatory monitors. Arrhythmias were present in 9 patients (12%). Within this group of 9 patients, 18/24 serial monitors were abnormal, and 3/9 patients (33%) had >1 arrhythmia type. Older age (p = 0.002) and symptoms (syncope, p = 0.005) were associated with arrhythmias. Arrhythmia was not associated with the degree of structural heart disease. Atrial tachycardia was the most identified arrhythmia (n = 6; 67% of patients with arrhythmias and 8% of the total cohort). The QTc abnormally increased with higher heart rates in all groups. There was a higher number of premature ventricular and atrial complexes per hour in patients with arrhythmias. In conclusion, atrial arrhythmias were the most common arrhythmia in patients with WS and routine ambulatory ECG and intermittent rhythm monitoring are indicated in WS, particularly given the high risk of sudden cardiac death in WS.

Longitudinal Assessment of Cardiac Function Following Multisystem Inflammatory Syndrome in Children Associated with COVID-19

Multisystem inflammatory syndrome in children (MIS-C) after COVID-19 is commonly associated with cardiac involvement. Studies found myocardial dysfunction, as measured by decreased ejection fraction and abnormal strain, to be common early in illness. However, there is limited data on longitudinal cardiac outcomes. We aim to describe the evolution of cardiac findings in pediatric MIS-C from acute illness through at least 2-month follow-up. A retrospective single-center review of 36 patients admitted with MIS-C from April 2020 through September 2021 was performed. Echocardiographic data including cardiac function and global longitudinal strain (GLS) were analyzed at initial presentation, discharge, 2-4-week follow-up, and at least 2-month follow-up. Patients with mild and severe disease, normal and abnormal left ventricular ejection fraction (LVEF), and normal and abnormal GLS at presentation were compared. On presentation, 42% of patients with MIS-C had decreased LVEF < 55%. In patients in whom GLS was obtained (N = 18), 44% were abnormal (GLS < |- 18|%). Of patients with normal LVEF, 22% had abnormal GLS. There were no significant differences in troponin or brain natriuretic peptide between those with normal and abnormal LVEF. In most MIS-C patients with initial LVEF < 55% (90%), LVEF normalized upon discharge. At 2-month follow-up, all patients had normal LVEF with 21% having persistently abnormal GLS. Myocardial systolic dysfunction and abnormal deformation were common findings in MIS-C at presentation. While EF often normalized by 2 months, persistently abnormal GLS was more common, suggesting ongoing subclinical dysfunction. Our study offers an optimistic outlook for recovery in patients with MIS-C and carditis, however ongoing investigation for longitudinal effects is warranted.

Importance of Formula-Specific Centile Thresholds for Evaluation of Heart Rate-Corrected QT Prolongation in Williams Syndrome

Patients with Williams syndrome (WS) have a 25- to 100-fold higher risk of sudden death and prolonged heart rate-corrected QT (QTc). A recent study using the Fridericia formula for QT correction suggested that prolongation is principally an issue of heart rate. We used multiple published heart rate correction formulas to reevaluate the prevalence of QTc prolongation in our original dataset from our 2010 study at the Children's Hospital of Philadelphia. The ninety-eighth centile for QTc and corrected JT Interval (JTc) of the control population for each formula were used to set the threshold for prolongation. Prevalence comparison was done with Fisher's exact test. Predictors of longer QTc/JTc were assessed using linear regression models adjusting for age, gender, and heart rate. Adjusted odds of QTc/JTc prolongation were evaluated with conditional logistic regression models matched based on age and heart rate. There were 482 electrocardiograms from 188 patients with WS and 1,522 from normal controls. Patients with WS were younger, with higher heart rates and shorter RR and QRS intervals. WS was associated with longer QTc/JTc compared with controls. There were higher odds of prolonged QTc/JTc in patients with WS than controls using both Bazett and Fridericia formulas. In conclusion, this study confirms the higher prevalence of QTc prolongation in WS compared with controls and highlights the importance of setting appropriate formula-specific upper thresholds for QTc prolongation for accurate diagnosis.