Section of Cardiology, Departments of Pediatrics and Internal Medicine, Yale University School of Medicine, 333 Cedar Street, P.O. Box 208064, New Haven, CT, 06520-8064, USA.
Frank H. Netter School of Medicine, Quinnipiac University, North Haven, CT, USA.
Pediatr Cardiol. 2022 Oct;43(7):1559-1567. doi: 10.1007/s00246-022-02883-3. Epub 2022 Apr 2.
QTc prolongation (≥ 460 ms), according to Bazett formula (QTcB), has been identified to be increased in Williams syndrome (WS) and suggested as a potential cause of increased risk of sudden cardiac death. The Bazett formula tends to overestimate QTc in higher heart rates. We performed a retrospective chart review of WS patients with ≥ 1 electrocardiogram (EKG) with sinus rhythm, no evidence of bundle branch blocks, and measurable intervals. A total of 280 EKGs from 147 patients with WS were analyzed and 123 EKGs from 123 controls. The QTc was calculated using Bazett formula. The average QTcB for individuals with WS and controls was 444 ± 24 ms and 417 ± 26 ms, respectively (p < 0.001). In our WS cohort 34.4% had at least 1 EKG with a QTcB ≥ 460 ms. The mean heart rate (HR) from patients with WS was significantly higher than controls (96 bpm vs 76 bpm, p < 0.001). Linear regression showed that HR contributed 27% to QTcB prolongation in the patients with WS. Patients with WS have a mean QTcB in the normal range but higher than controls, and a higher than expected frequency of QTc ≥ 460 ms compared to the general population. HR is also higher in WS and contributes modestly to the WS QTcB prolongation. Future studies are needed to assess if these findings contribute risk to sudden cardiac death but in the interim we recommend routine EKG testing, especially when starting QTc prolonging medications.
QTc 延长（≥460ms），根据 Bazett 公式（QTcB），在威廉姆斯综合征（WS）中被发现增加，并被认为是增加心源性猝死风险的潜在原因。Bazett 公式在较高心率时往往会高估 QTc。我们对窦性心律、无束支传导阻滞且可测量间隔的 WS 患者进行了回顾性图表审查，这些患者至少有一次心电图（EKG）。共分析了 147 例 WS 患者的 280 份 EKG 和 123 例对照的 123 份 EKG。使用 Bazett 公式计算 QTc。WS 患者和对照组的平均 QTcB 分别为 444±24ms 和 417±26ms（p<0.001）。在我们的 WS 队列中，34.4%的人至少有一次 EKG 的 QTcB≥460ms。WS 患者的平均心率（HR）明显高于对照组（96bpm 与 76bpm，p<0.001）。线性回归显示，HR 对 WS 患者的 QTcB 延长贡献了 27%。WS 患者的平均 QTcB 在正常范围内，但高于对照组，与一般人群相比，QTc≥460ms 的频率也高于预期。WS 中的 HR 也较高，对 WS 的 QTcB 延长有一定贡献。需要进一步研究这些发现是否会导致心源性猝死风险增加，但在此期间，我们建议常规进行心电图检查，尤其是在开始使用延长 QTc 的药物时。
