PROBUCOL-INDUCED QT PROLONGATION AND SYNCOPE

We report a patient who experienced a reversible prolongation of the Q T interval and episodes of syncope while receiving probucol. A 64-year -old woman experienced syncopal attacks 8 and 11 weeks after beginning probucol treatment (500 mg twice daily). The pre-treatment ECG showed a slight prolongation of the corrected QT interval (QTc) (0.46 sec). Her QTc increased to 0.62 sec 12 weeks after beginning probucol treatm ent and decreased to about the baseline value (0.48 sec) 6 weeks after treatment was discontinued. Probucol is known to prolong the QT inter val. A long QT interval has been linked to an increased risk of ventri cular arrhythmias, syncope or sudden death. However, clinical reports which causally relate probucol treatment to syncope are very rare. Alt hough an ECG during the episodes of syncope was not available, this pa tient's syncope might be due to ventricular tachyarrhythmia associated with probucol-induced QT prolongation. This case emphasizes the need for careful evaluation of the QT interval before and during probucol t reatment.