Page Alex, Aktas Mehmet K, Soyata Tolga, Zareba Wojciech, Couderc Jean-Philippe
Electrical and Computer Engineering Department, University of Rochester, Rochester, New York.
Cardiology Department, University of Rochester Medical Center, Rochester, New York.
Heart Rhythm. 2016 Jan;13(1):190-8. doi: 10.1016/j.hrthm.2015.08.037. Epub 2015 Aug 31.
The QT interval is a risk marker for cardiac events such as torsades de pointes. However, QT measurements obtained from a 12-lead ECG during clinic hours may not capture the full extent of a patient's daily QT range.
The purpose of this study was to evaluate the utility of 24-hour Holter ECG recording in patients with long QT syndrome (LQTS) to identify dynamic changes in the heart rate-corrected QT interval and to investigate methods of visualizing the resulting datasets.
Beat-to-beat QTc (Bazett) intervals were automatically measured across 24-hour Holter recordings from 202 LQTS type 1, 89 type 2, and 14 type 3 genotyped patients and a reference group of 200 healthy individuals. We measured the percentage of beats with QTc greater than the gender-specific threshold (QTc ≥470 ms in women and QTc ≥450 ms in men). The percentage of beats with QTc prolongation was determined across the 24-hour recordings.
Based on the median percentage of heartbeats per patient with QTc prolongation, LQTS type 1 patients showed more frequent QTc prolongation during the day (3 PM) than they did at night (3 AM): 97% vs 48%, P ~10(-4) for men, and 68% vs 30%, P ~10(-5) for women. LQTS type 2 patients showed less frequent QTc prolongation during the day compared to nighttime: 87% vs 100%, P ~10(-4) for men, and 62% vs 100%, P ~10(-3) for women.
In patients with genotype-positive LQTS, significant differences exist in the degree of daytime and nocturnal QTc prolongation. Holter monitoring using the "QT clock" concept may provide an easy, fast, and accurate method for assessing the true personalized burden of QTc prolongation.
QT间期是诸如尖端扭转型室速等心脏事件的风险标志物。然而，在临床时间从12导联心电图获得的QT测量值可能无法反映患者每日QT范围的全貌。
本研究的目的是评估24小时动态心电图记录在长QT综合征（LQTS）患者中的效用，以识别心率校正QT间期的动态变化，并研究可视化所得数据集的方法。
对202例1型、89例2型和14例3型基因分型的LQTS患者以及200名健康个体的参考组进行24小时动态心电图记录，自动测量逐搏QTc（Bazett）间期。我们测量了QTc大于性别特异性阈值（女性QTc≥470毫秒，男性QTc≥450毫秒）的搏动百分比。在24小时记录中确定QTc延长的搏动百分比。
根据每位患者QTc延长的心跳中位数百分比，1型LQTS患者白天（下午3点左右）QTc延长比夜间（凌晨3点左右）更频繁：男性为97%对48%，P约为10⁻⁴；女性为68%对30%，P约为10⁻⁵。2型LQTS患者白天QTc延长比夜间少：男性为87%对100%，P约为10⁻⁴；女性为62%对100%，P约为10⁻³。
在基因型阳性的LQTS患者中，白天和夜间QTc延长程度存在显著差异。使用“QT时钟”概念的动态心电图监测可能为评估QTc延长的真正个性化负担提供一种简单、快速且准确的方法。
