Zambruni Andrea, Di Micoli Antonio, Lubisco Alessandro, Domenicali Marco, Trevisani Franco, Bernardi Mauro
Department of Internal Medicine, Cardioangiology and Hepatology, Policlinico S. Orsola-Malpighi Alma Mater Studiorum, University of Bologna, Bologna, Italy.
J Cardiovasc Electrophysiol. 2007 Jan;18(1):77-82. doi: 10.1111/j.1540-8167.2006.00622.x.
QT interval prolongation is a common electrophysiological abnormality in patients with cirrhosis. As QT interval varies with the heart rate, many QT correction formulas have been proposed, the Bazett's one being the most criticized because it over-corrects the QT interval and may be misleading. This study focused on the QT-RR relationship in patients with cirrhosis to derive a population-specific QT correction formula.
One hundred cirrhotic patients of different etiology and severity and 53 healthy controls comparable for age and sex were enrolled. The QT-RR relationship was analyzed in patients by five regression analysis models to derive the population-specific QT-RR equation. The QTc was calculated and compared with those calculated by four common QT correction formulas (Bazett, Fridericia, Framingham, and Hodges). The correlation coefficient QTc-RR was calculated as a measure of the independence of QTc from the original RR interval.
In patients the QT-RR relationship was best described by the power equation "QT = 453.65 x RR1/3.02" (R2 = 0.41), similar to the Fridericia's formula. Bazett's formula led to the longest QTc (P < 0.0001), which was still significantly influenced by the RR interval (R = -0.39; P < 0.0001), while the estimated equation led to a QTc value not influenced by RR (R = -0.014).
Bazett's correction should be avoided in patients with cirrhosis because it still provides a rate-dependent QTc value and might be misleading, particularly when assessing the overall preoperative cardiac risk and the effect of drugs affecting the QT interval. In its place, our formula or that of Fridericia can be confidently employed.
QT间期延长是肝硬化患者常见的电生理异常。由于QT间期随心率变化，人们提出了许多QT校正公式，其中Bazett公式受到的批评最多，因为它过度校正QT间期，可能会产生误导。本研究聚焦于肝硬化患者的QT-RR关系，以推导特定人群的QT校正公式。
纳入100例不同病因和严重程度的肝硬化患者以及53例年龄和性别匹配的健康对照。通过五种回归分析模型分析患者的QT-RR关系，以推导特定人群的QT-RR方程。计算校正QT间期（QTc），并与四种常用QT校正公式（Bazett、Fridericia、Framingham和Hodges）计算的结果进行比较。计算QTc-RR相关系数，以衡量QTc与原始RR间期的独立性。
在患者中，QT-RR关系用幂方程“QT = 453.65 x RR1/3.02”（R2 = 0.41）描述最佳，类似于Fridericia公式。Bazett公式导致最长的QTc（P < 0.0001），其仍受RR间期显著影响（R = -0.39；P < 0.0001），而估计方程得出的QTc值不受RR影响（R = -0.014）。
肝硬化患者应避免使用Bazett校正，因为它仍提供心率依赖性QTc值，可能会产生误导，特别是在评估术前总体心脏风险和影响QT间期的药物效果时。取而代之的是，可以放心采用我们的公式或Fridericia公式。
