QT dispersion significantly increases after implantable cardioverter-defibrillator shocks.
OBJECTIVE
To determine whether QT dispersion (QTd), a noninvasive electrocardiographic parameter of ventricular tachyarrhythmia risk assessment, is changed by implantable cardioverter-defibrillator (ICD) shocks delivered during implantation process, to analyze the duration of these changes, and to further evaluate the effect of amiodarone on these parameters.


METHODS
Twenty-six consecutive patients who are scheduled to undergo ICD implantation for aborted sudden cardiac death or documented symptomatic sustained ventricular tachycardia were enrolled into the study. A simultaneous 12-lead electrocardiogram (ECG) was recorded after the ICD implantation just before starting the testing shock when the patients were under general anesthesia (baseline record) and at 1st, 5th, 10th, 15th, 20th, 25th, and 30th minutes after the successful shocks. RR interval, QT interval, corrected QT interval (QTc), QTd, and corrected QTd (QTcd) were all measured and calculated on ECG.


RESULTS
At 1st minute after the successful shock, an abrupt increase (from 67.0 +/- 13.8 ms to 94.8+/-21 ms, P < 0.0001) was observed in QTcd, which was followed by a gradual return to the preshock values at 20th minute. Analysis of patients with and without long-term oral amiodarone treatment showed that in amiodarone-pretreated patients QTcd returned to the baseline value earlier than in patients without amiodarone treatment (15 minutes vs 20 minutes, respectively).


CONCLUSIONS
ICD shocks cause an increase in QTcd lasting for up to 20th minute, which may predominate in some important clinical problems like electrical storm. Amiodarone, with the desirable effect on QTcd, may reduce the proarrhythmic effects of ICD shocks.
Topaloglu
Serkan
S
Turkiye Yüksek Ihtisas Hospital, Department of Cardiology, Ankara, Turkey. topaloglus@yahoo.com
Aras
Dursun
D
Sahin
Onur
O
Ergun
Kumral
K
Deveci
Bulent
B
Ozdemir
Ozcan
O
Ozeke
Ozcan
O
Yildiz
Ali
A
Alyan
Omer
O
Demir
Ahmet Duran
AD
Soylu
Mustafa
M
Kisacik
Halil Lutfi
HL
Korkmaz
Sule
S
D000328:Adult; D000368:Aged; D000638:Amiodarone / Q000494:pharmacology / Q000627:therapeutic use; D000889:Anti-Arrhythmia Agents / Q000494:pharmacology / Q000627:therapeutic use; D017147:Defibrillators, Implantable; D004554:Electric Countershock; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011292:Premedication; D017180:Tachycardia, Ventricular / Q000188:drug therapy / Q000503:physiopathology / Q000628:therapy*
D000889:Anti-Arrhythmia Agents; D000638:Amiodarone