Increase in QT/QTc dispersion after low energy cardioversion of chronic persistent atrial fibrillation

An Improved QT Correction Method for use in Atrial Fibrillation and a Comparison with the Assessment of QT in Sinus Rhythm.

“…Studies that have directly compared QT intervals in SRand AF using the Bazett correction have found the QT in SR to be either shorteror no different than that in AF. 15,24,25 However, other observations are consistent with theinterpretation that the QT may be shorter in AF compared to SR. For example, inthe study of Larroude et. al., although ΔQT/ ΔRRmodin SR was nearly parallel to that for AF, the AF relationship had both a lowery-intercept and a lower QT at the "standard" heart rate of 60 .…”

QT Dispersion Significantly Increases after Implantable Cardioverter‐Defibrillator Shocks

“…In a previous report Boriani et al 18 showed a significant increase in QTd after successful internal atrial cardioversion for atrial fibrillation. Since they reported no increase in QTd after unsuccessful shocks, they could not explain the increase in QTd is because of either the direct effect of shock or conversion to sinus rhythm.…”

Implantable Cardioverter‐Defibrillator Shocks Increase T‐Wave Alternans

“…Similarly, we cannot exclude the possibility that the preceding programmed stimulation or the shock delivered on the T wave to induce VF may have contributed to increased TWA, as these shocks increase spatial dispersion of repolarization measured invasively 35 . However, shocks delivered to terminate atrial fibrillation have also induced electrophysiological changes, despite the absence of preceding VF or T‐wave‐delivered shock, although TWA has not been evaluated 23 …”

“…Data are few on electrophysiological effects of defibrillating ICD shock in humans. Two studies have shown that QT dispersion as measured from a 12‐lead ECG increases after shock 23 . However, the limitations of QT dispersion as a marker of repolarization heterogeneity are well described 24 .…”