Stanford University, Division of Cardiovascular Medicine, Stanford, California.
Cardiac Insight, Inc, Kirkland, Washington.
Am J Cardiol. 2019 Jun 1;123(11):1822-1827. doi: 10.1016/j.amjcard.2019.02.057. Epub 2019 Mar 13.
Antiarrhythmic drugs used in atrial fibrillation (AF) cause QT prolongation and are associated with torsades de pointes, a deadly ventricular arrhythmia. No consensus exists on the optimal method of QT measurement or correction in AF. Therefore, we compared common methods to measure and correct QT in AF to identify the most accurate approach. We identified patients who had electrocardiograms done at Stanford Hospital (Stanford, California) between January 2014 and October 2016 with conversion from AF to sinus rhythm (SR) within a 24-hour period. QT intervals were determined using different measurement methods and corrected using the Bazett's, Framingham, Fridericia, or Hodges formulas for heart rate (HR). Comparisons were made between QT in a patient's last instance of AF to SR. Computerized measurements were taken from 715 patients. Manual measurements were taken from a 50-patient subset. Bazett's formula produced the longest corrected QT in AF compared with other formulas (p <0.005). Measuring QT as an average over multiple beats resulted in a smaller difference between AF and SR than choosing a single beat. Determining QT from a 5-beat average resulted in a QTc that was 19.0 ms higher (interquartile range 0.30 to 43.7) in AF than SR. After correcting for residual effect of HR on QTc, there was not a significant difference between QTc in AF to SR. In conclusion, measuring QT over multiple beats produces a more accurate measurement of QT in AF. Differences between QTc in AF and SR exist because of imperfect HR correction formula and not due to an independent effect of AF.
抗心律失常药物在心房颤动（AF）中使用会导致 QT 延长，并与尖端扭转型室性心动过速（TdP）相关，这是一种致命的室性心律失常。目前对于 AF 中 QT 测量或校正的最佳方法尚无共识。因此，我们比较了 AF 中测量和校正 QT 的常用方法，以确定最准确的方法。我们确定了 2014 年 1 月至 2016 年 10 月期间在斯坦福医院（加利福尼亚州斯坦福）进行心电图检查并在 24 小时内从 AF 转为窦性节律（SR）的患者。使用不同的测量方法确定 QT 间期，并使用 Bazett、Framingham、Fridericia 或 Hodges 公式校正心率（HR）。比较了患者最后一次 AF 到 SR 的 QT。计算机测量了 715 例患者，手动测量了 50 例患者的子集。与其他公式相比，Bazett 公式在 AF 中产生的校正 QT 最长（p<0.005）。与选择单个节拍相比，对多个节拍的 QT 进行平均测量会导致 AF 和 SR 之间的差异较小。从 5 个节拍的平均值确定 QT 会导致 QTc 在 AF 中比在 SR 中高 19.0 ms（四分位距 0.30 至 43.7）。校正 HR 对 QTc 的残留影响后，AF 与 SR 之间的 QTc 无显著差异。总之，对多个节拍的 QT 进行测量可更准确地测量 AF 中的 QT。AF 中 QTc 和 SR 之间的差异是由于 HR 校正公式不完美，而不是由于 AF 的独立影响。
