Mechanism of repolarization change during initiation of supraventricular tachycardia.
BACKGROUND
Previous literature has documented the association between narrow QRS supraventricular tachycardia (SVT) and pronounced ST-T segment change. The aim of this study was to evaluate repolarization changes during SVT initiation and demonstrate the possible mechanism.


RESULTS
Fifty-one consecutive patients (20 men and 31 women; mean age 46.1 +/- 16.4 years) with narrow QRS SVT (32 patients with AV nodal reentrant tachycardia and 19 patients with AV reentrant tachycardia) were included. We retrospectively analyzed the intracardiac recordings and ST-T segment changes on 12-lead surface ECGs during SVT initiation. Twenty-six (51%) patients developed ST segment repolarization changes during SVT initiation. Patients with shorter baseline sinus cycle length, shorter tachycardia cycle length, elevated systolic blood pressure before tachycardia induction, and greater reduction of systolic blood pressure had a higher incidence of repolarization changes. However, multivariate analysis showed that reduction of systolic blood pressure after SVT induction was the only independent predictor of repolarization changes. Furthermore, the maximal degree of ST segment depression during SVT correlated with the reduction of systolic blood pressure (r = 0.75, P < 0.001).


CONCLUSIONS
Repolarization changes during SVT initiation were caused mainly by concurrent hemodynamic change after SVT initiation with abrupt cycle length shortening.
Lin
Yenn-Jiang
YJ
Division of Cardiology, Department of Medicine, National Yang-Ming University, School of Medicine, and Taipei Veterans General Hospital, Taipei, Taiwan.
Tai
Ching-Tai
CT
Chiang
Chen-En
CE
Lee
Kun-Tai
KT
Yuniadi
Yoga
Y
Huang
Bien-Hsien
BH
Liu
Tu-Ying
TY
Lee
Pi-Chiang
PC
Kuo
Jen-Yuan
JY
Chen
Shih-Ann
SA
D000328:Adult; D004562:Electrocardiography; D004594:Electrophysiology; D005260:Female; D006329:Heart Conduction System / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011226:Pre-Excitation Syndromes / Q000503:physiopathology*; D012189:Retrospective Studies; D013617:Tachycardia, Supraventricular / Q000175:diagnosis / Q000503:physiopathology*