Open AccessQT Dispersion as a Marker for Response to Quinidine in Patients with Ventricular Tachyarrhythmias
Author(s) -
Kertland Heather,
White C. Michael,
Chow Moses S.S.,
Kluger Jeffrey
Publication year - 2000
Publication title -
annals of noninvasive electrocardiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.494
H-Index - 48
eISSN - 1542-474X
pISSN - 1082-720X
DOI - 10.1111/j.1542-474x.2000.tb00244.x
Subject(s) - quinidine , medicine , ventricular tachycardia , qt interval , cardiology , dispersion (optics) , tachycardia , electrocardiography , anesthesia , optics , physics
Objective: This study was undertaken to measure the effect of quinidine on QT dispersion and to determine whether changes in QT dispersion are associated with the acute response to quinidine in patients with ventricular tachycardia. Methods: In 36 patients with inducible ventricular tachycardia during programmed electrical stimulation (PES), QT and JT intervals were measured in all 12 leads of electrocardiograms recorded at baseline and after quinidine. QT/JT dispersion was calculated by subtracting the smallest from the largest interval; QTc and JTc dispersion were also calculated. Response to therapy was defined as the inability to induce a ventricular tachyarrhythmia during a repeat PES study. Results: Quinidine significantly prolonged the QTc and JTc intervals in the patients who responded to quinidine (n = 12) and in the nonresponders (n = 24). At baseline, QTc dispersion was similar in responders and nonresponders. However, quinidine increased QTc dispersion in nonresponders (from 78 ± 28 to 113 ± 40 ms, P < 0.05) but not in responders (from 81 ± 26 to 83 ± 42 ms). A similar pattern was seen for QT dispersion, JT dispersion, and JTc dispersion. Conclusion: QT dispersion increases in nonresponders, but not in responders to quinidine for ventricular tachycardia. This QT dispersion profile is distinct from the Class III antiarrhythmics and may explain results from large clinical trials and delineate a new safety and efficacy marker.