Department of Molecular and Clinical Medicine, Institute of Medicine, Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
Region Västra Götaland, Department of Cardiology, Sahlgrenska University Hospital, Gothenburg, Sweden.
Ann Noninvasive Electrocardiol. 2021 Jan;26(1):e12804. doi: 10.1111/anec.12804. Epub 2020 Oct 18.
The heart rate (HR) corrected QT interval (QTc) is crucial for diagnosis and risk stratification in the long QT syndrome (LQTS). Although its use has been questioned in some contexts, Bazett's formula has been applied in most diagnostic and prognostic studies in LQTS patients. However, studies on which formula eliminates the inverse relation between QT and HR are lacking in LQTS patients. We therefore determined which QT correction formula is most appropriate in LQTS patients including the effect of beta blocker therapy and an evaluation of the agreement of the formulae when applying specific QTc limits for diagnostic and prognostic purposes.
Automated measurements from routine 12-lead ECGs from 200 genetically confirmed LQTS patients from two Swedish regions were included (167 LQT1, 33 LQT2). QT correction was performed using the Bazett, Framingham, Fridericia, and Hodges formulae. Linear regression was used to compare the formulae in all patients, and before and after the initiation of beta blocking therapy in a subgroup (n = 44). Concordance analysis was performed for QTc ≥ 480 ms (diagnosis) and ≥500 ms (prognosis).
The median age was 32 years (range 0.1-78), 123 (62%) were female and 52 (26%) were children ≤16 years. Bazett's formula was the only method resulting in a QTc without relation with HR. Initiation of beta blocking therapy did not alter the result. Concordance analyses showed clinically significant differences (Cohen's kappa 0.629-0.469) for diagnosis and prognosis in individual patients.
Bazett's formula remains preferable for diagnosis and prognosis in LQT1 and 2 patients.
心率（HR）校正 QT 间期（QTc）对长 QT 综合征（LQTS）的诊断和风险分层至关重要。尽管在某些情况下对其使用存在质疑，但巴泽特（Bazett）公式已应用于大多数 LQTS 患者的诊断和预后研究中。然而，在 LQTS 患者中，缺乏关于哪种 QT 校正公式能消除 QT 与 HR 之间的反比关系的研究。因此，我们确定了哪种 QT 校正公式在 LQTS 患者中最适用，包括β受体阻滞剂治疗的影响，以及在应用特定的 QTc 限值进行诊断和预后目的时，这些公式的一致性评估。
纳入了来自瑞典两个地区的 200 名经基因证实的 LQTS 患者（167 名 LQT1，33 名 LQT2）的常规 12 导联心电图的自动测量值。使用巴泽特（Bazett）、弗雷明汉（Framingham）、弗赖迪希（Fridericia）和霍奇斯（Hodges）公式进行 QT 校正。在所有患者中，使用线性回归比较了这些公式，在一个亚组（n=44）中，比较了开始β受体阻滞剂治疗前后的公式。对于 QTc≥480ms（诊断）和 QTc≥500ms（预后）进行了一致性分析。
中位年龄为 32 岁（范围 0.1-78），123 名（62%）为女性，52 名（26%）为≤16 岁的儿童。巴泽特（Bazett）公式是唯一一种导致 QTc 与 HR 无相关性的方法。开始β受体阻滞剂治疗并未改变结果。在个体患者中，诊断和预后的一致性分析显示出具有临床意义的差异（科恩氏κ0.629-0.469）。
巴泽特（Bazett）公式仍然是 LQT1 和 2 患者诊断和预后的首选方法。
