Chambers J B, Ward D E
Am Heart J. 1987 Aug;114(2):355-61. doi: 10.1016/0002-8703(87)90503-5.
The QT interval was plotted against the R-R interval in 92 patients with mitral prolapse and 92 age- and sex-matched control subjects. Ten patients (11%) lay above the upper 95% confidence limit for the control group, and analysis of variance confirmed a small group effect (p less than 0.05). Despite this, the mean QT intervals in the two groups differed by only 7 msec and a t test showed no significant difference between the groups. The prevalence of QT prolongation was exaggerated by Bazett's rate correction formula (62%) or historical control groups published by Simonson (58%) or Ashman (70%). Simultaneous QT and QS2 intervals were measured in 67 patients with mitral prolapse. Inversion of the normal QT:QS2 relationship occurred in nine patients (13%) and was more common in the presence of severe mitral regurgitation. It was not associated with an increased prevalence of absolute QT prolongation and was therefore thought to be caused by relative shortening of the QS2 interval. In conclusion, the prevalence of QT prolongation in mitral prolapse is low (11%). The QT:QS2 ratio is unlikely to be a reliable indicator of QT prolongation in these patients.
对92例二尖瓣脱垂患者以及92例年龄和性别匹配的对照者，绘制QT间期与R-R间期的关系图。10例患者（11%）位于对照组95%可信区间上限之上，方差分析证实存在小的组间效应（p<0.05）。尽管如此，两组的平均QT间期仅相差7毫秒，t检验显示两组间无显著差异。Bazett心率校正公式（62%）、Simonson发表的历史对照组（58%）或Ashman（70%）所报道的QT延长患病率均被夸大。对67例二尖瓣脱垂患者同时测量QT和QS2间期。9例患者（13%）出现正常QT:QS2关系倒置，在重度二尖瓣反流患者中更常见。它与绝对QT延长患病率增加无关，因此被认为是由QS2间期相对缩短所致。总之，二尖瓣脱垂患者中QT延长的患病率较低（11%）。QT:QS2比值不太可能是这些患者QT延长的可靠指标。
