FACTORS RELATED TO QT INTERVAL PROLONGATION DURING PROBUCOL TREATMENT

To clarify factors related to the QT interval prolongation produced by probucol, multivariate analysis was applied to clinical and laboratory data retrospectively obtained from 89 patients with hypercholesterolaemia, who had taken probucol for more than 3 months. The corrected QT interval (QT(c)) increased from 0.410 s before treatment to 0.431 s after the administration of probucol; the total cholesterol level decreased from 267 mg . dl-1 to 212 mg . dl-1. None of the patients demonstrated new arrhythmia. The QT(c) after probucol was independently correlated with sex, serum albumin level and baseline QT(c). Changes in QT(c) after probucol were independently correlated with the presence of ischaemic heart disease, baseline QT(c), and a change in the total cholesterol level. The results suggest that a prolonged QT(c) is likely to appear in female patients, and in patients with a long baseline QT(c) or with a low serum albumin. It is also suggested that marked lengthening of the QT(c) is likely to occur in patients with ischaemic heart disease or with a short baseline QT(c). Probucol can be used safely in patients with hypercholesterolaemia, but ECG monitoring may be necessary, especially in female patients, as well as in those with hypoalbuminaemia or with ischaemic heart disease.