Long-term efficacy of low doses of quinidine on malignant arrhythmias in Brugada syndrome with an implantable cardioverter-defibrillator: a case series and literature review.
BACKGROUND
To prevent the recurrence of ventricular arrhythmias (VA) in Brugada syndrome (BrS), only quinidine has been consistently reported to have a beneficial effect. Recommended doses are ≥ 1 g/d. The efficacy of lower doses of quinidine has been suggested on the basis of a few isolated experiences.


OBJECTIVE
To describe the efficacy and safety of doses ≤ 600 mg/d of quinidine after cardioverter-defibrillator implantation in BrS at 2 referral centers and to compare those results with a comprehensive review of the literature.


METHODS
In a retrospective analysis of medical records from the 2 centers, 6 men with BrS who received ≤ 600 mg/d of quinidine sulfate or hydroquinidine after cardioverter-defibrillator implantation were identified. Quinidine was initiated after arrhythmic syncope or appropriate shocks, including arrhythmic storm in 4. A literature search was performed to find previous cases with symptomatic BrS reported as having received ≤ 600 mg/d of quinidine.


RESULTS
Quinidine prevented recurrence of VA in all patients from our series without side effects during a median follow-up of 4 years (from 2 to 8 years). In the literature review, 14 additional adults were found. With the exception of 3, quinidine effectively suppressed arrhythmic events in all of them. Four subjects who discontinued the medication experienced VA recurrence, successfully treated by restarting quinidine.


CONCLUSIONS
Low doses of quinidine were well tolerated and effective to prevent the recurrence of VA, including arrhythmic storm, in subjects with BrS with an implantable cardioverter-defibrillator. Effectiveness of quinidine or hydroquinidine in doses ≤ 600 mg/d is 85%.
Department of Electrophysiology, Instituto Nacional de Cardiología Ignacio Chávez, Mexico City, México. manlio.marquez@gmail.com
Manlio F
MF
Márquez
Aimé
A
Bonny
Eduardo
E
Hernández-Castillo
Antonio
A
De Sisti
Jorge
J
Gómez-Flores
Santiago
S
Nava
Françoise
F
Hidden-Lucet
Pedro
P
Iturralde
Manuel
M
Cárdenas
Joelci
J
Tonet
D000328:Adult; D000889:Anti-Arrhythmia Agents / Q000627:therapeutic use; D053840:Brugada Syndrome / Q000503:physiopathology / Q000628:therapy*; D017147:Defibrillators, Implantable; D004562:Electrocardiography; D005260:Female; D005500:Follow-Up Studies; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011802:Quinidine / Q000627:therapeutic use*; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome
D000889:Anti-Arrhythmia Agents; D011802:Quinidine