Division of Cardiology, Department of Medical Sciences, 'Città della Salute e della Scienza' Hospital, University of Turin.
Pinna Pintor Clinic, Turin, Italy.
J Cardiovasc Med (Hagerstown). 2019 Apr;20(4):180-185. doi: 10.2459/JCM.0000000000000773.
QT interval may be considered an indirect marker of atrial repolarization. Aim of our study was to verify if QT interval variations precede the onset of atrial fibrillation (AF).
We analyzed 21 AF onsets recorded at 24-h Holter ECG. Triggering supraventricular extrabeats (TSVEB) were identified and matched to nontriggering supraventricular extrabeats (NTSVEB) with the same prematurity index. QT and QTc intervals and their variability (max-min QT interval) were measured in the 10 beats preceding TSVEB and NTSVEB.
QTc (470.1 ± 56.7 vs. 436.7 ± 25.6 ms; P = 0.006), QT (36.8 ± 13.1 vs. 21.1 ± 10.1 ms; P = 0.001) and QTc variability (41.5 ± 15.8 vs. 23.1 ± 11.9; P = 0.001) significantly varied between TSVEB and NTSVEB. By stratifying AF onsets in vagal (n = 10) and adrenergic (n = 11) according to Heart Rate Variability, significant differences emerged concerning QT (35.20 ± 16.48 vs. 22.70 ± 10.23 ms, P = 0.006) and QTc variability (39.30 ± 18.32 vs. 25.60 ± 12.91 ms, P = 0.029) for vagal onsets and QTc (477.73 ± 57.50 vs. 438.00 ± 28.55 ms, P = 0.045), QT (38.36 ± 9.79 vs. 19.73 ± 10.21 ms, P = 0.005) and QTc variability (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.004) for adrenergic onsets. By stratifying AF onsets in type I (n = 7) or II (n = 14) according to a cycle length variation in the 30 s before the onset greater or smaller than 10% respectively, significant differences were noted concerning QTc (477.73 ± 57.50 vs. 438 ± 28.55 ms, P = 0.045), QT (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.005) and QTc variability (43.55 ± 13.72 vs. 20.82 ± 11.01 ms, P = 0.004) in type I and QT (35.20 ± 16.48 vs. 22.70 ± 10.23 ms, P = 0.006) and QTc variability (39.30 ± 18.32 vs. 25.60 ± 12.91 ms, P = 0.029) in type II onsets.
Prolongation and QT variability represent a relevant substrate marker in the genesis of AF, independently of the trigger type.
QT 间期可被视为心房复极的间接标志物。本研究旨在验证 QT 间期的变化是否先于心房颤动（AF）的发生。
我们分析了 24 小时动态心电图记录的 21 次 AF 发作。确定触发性室上性期前收缩（TSVEB）并将其与具有相同提前指数的非触发性室上性期前收缩（NTSVEB）相匹配。在 TSVEB 和 NTSVEB 之前的 10 个搏动中测量 QT 和 QTc 间期及其变异性（最大-最小 QT 间期）。
与 NTSVEB 相比，QTc（470.1±56.7 与 436.7±25.6 ms；P=0.006）、QT（36.8±13.1 与 21.1±10.1 ms；P=0.001）和 QTc 变异性（41.5±15.8 与 23.1±11.9；P=0.001）差异显著。根据心率变异性，将 AF 发作分为迷走神经（n=10）和肾上腺素（n=11），QT（35.20±16.48 与 22.70±10.23 ms，P=0.006）和 QTc 变异性（39.30±18.32 与 25.60±12.91 ms，P=0.029）以及迷走神经发作时的 QTc（477.73±57.50 与 438.00±28.55 ms，P=0.045）、QT（38.36±9.79 与 19.73±10.21 ms，P=0.005）和 QTc 变异性（43.55±13.72 与 20.82±11.01 ms，P=0.004）差异显著。根据发作前 30 秒的周期长度变化大于或小于 10%，将 AF 发作分为 I 型（n=7）或 II 型（n=14），QTc（477.73±57.50 与 438.0±28.55 ms，P=0.045）、QT（43.55±13.72 与 20.82±11.01 ms，P=0.005）和 QTc 变异性（43.55±13.72 与 20.82±11.01 ms，P=0.004）以及 I 型发作时的 QT（35.20±16.48 与 22.70±10.23 ms，P=0.006）和 QTc 变异性（39.30±18.32 与 25.60±12.91 ms，P=0.029）差异显著。
QT 间期的延长和变异性是 AF 发生的重要基质标志物，与触发类型无关。
