Time dependent changes in duration of ventricular repolarization after AV node ablation: Insights into the possible mechanism of postprocedural sudden death
J. Dizon et al., Time dependent changes in duration of ventricular repolarization after AV node ablation: Insights into the possible mechanism of postprocedural sudden death, PACE, 23(10), 2000, pp. 1539-1544
Citations number
17
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
Although effective, there is a disturbing incidence of sudden death after A
V node ablation. The mechanism may be related to proarrhythmia associated w
ith prolongation in ventricular repolarization from the sudden decrease in
heart rate. To examine this issue, we studied 15 patients undergoing comple
te radiofrequency ablation of the AV node for rapid atrial arrhythmias. Twe
lve-lead ECGs of paced rhythms at rates of 60, 80, 100, and 120 beats/min w
ere recorded at time points of 30 minutes, 24 hours, 1 week, and 1 month af
ter ablation. The QT interval was measured in the limb and precordial leads
with the best T wave offset. The change in the QT interval (Delta QT) rela
tive to the measurement at 30-minute postablation was calculated. For compa
rison, a similar procedure was performed on patients receiving pacemakers f
or primary bradycardia (n = 5). The mean QT interval at 60 beats/min, 30-mi
nutes postablation was significantly longer than at time points thereafter
(482 +/- 39 vs 446 +/- 28 ms at 1 month, limb leads, for example, P < 0.05)
. Analysis of <Delta>QT revealed a significant shortening of the QT interva
l at nearly every paced rate at every time point relative to the value at 3
0-minute postablation. The QT intervals shortened and stabilized after 24 h
ours. Neither the QT interval nor Delta QT changed significantly in patient
s paced for primary bradycardia. We conclude that there is a relative incre
ase in the duration of ventricular repolarization after AV node ablation, w
hich then decreases and stabilizes after 24 hours. Such changes are not see
n in patients being paced for primary bradycardia. This data is consistent
with the hypothesis that sudden death after AV node ablation may be related
to proarrhythmia from prolonged ventricular repolarization.