Key result
Adaptation of ventricular repolarization duration was significantly more rapid following increasing heart rate than decreasing heart rate (difference of 24 s; P=0.006).
Why the study?
Does the adaptation of ventricular repolarization time differ following abrupt increases versus decreases in heart rate during atrial and ventricular pacing?
Does the adaptation of ventricular repolarization time differ following abrupt increases versus decreases in heart rate during atrial and ventricular pacing?
Mean Difference: 24
Absolute Event Rate: 103% vs 126%
p-value: p=0.006
Ventricular repolarization duration adapts significantly faster to abrupt increases in heart rate compared to decreases, and this process is intraindividually reproducible.
QT adaptation asymmetry during atrial pacing may affect ECG interpretation; leaves open prospective validation for arrhythmia risk stratification.
During atrial pacing, the CL decreased on average 45% from mean (SD) 944 (120) to 518 (46) ms and QT decreased on average 18% from 388 (20) to 318 (17) ms. For QT, T90 End was 103 (24) s and 126 (15) s after start versus stop of atrial pacing; a difference of 24 (27) s ( P = 0.006). The response pattern was similar for τ but IR did not differ significantly between pacing start and stop. The response pattern was similar for QT peak and also for QT and QT peak following ventricular pacing start and stop. The coefficients of variation for repeated measures were 7%–21% for T90 End and τ. In conclusion, the adaptation of VR duration was significantly more rapid following increasing than decreasing HR and intraindividually a relatively reproducible process.
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Axelsson et al. (2020) studied this question. Atrial and ventricular pacing (increasing heart rate) vs. Stop of pacing (decreasing heart rate) was evaluated on T90 End for QT (MD 24, p=0.006). Adaptation of ventricular repolarization duration was significantly more rapid following increasing heart rate than decreasing heart rate (difference of 24 s; P=0.006).
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