DOES SUBCLINICAL HYPOTHYROIDISM EXPLAIN THE INCREASED SUSCEPTIBILITY OF WOMEN TO TORSADES-DE-POINTES

There is now mounting evidence for an increased propensity of women to develop torsades de pointes induced by a variety of QT-prolonging dru gs.(1-3) This sex difference in proarrhythmia risk is complemented by a similar observation of a greater female susceptibility to torsades d e pointes in non-drug settings of QT prolongation, e.g., congenital lo ng QT syndrome(4,5) and bradycardia associated with complete heart blo ck.(6) Altered thyroid metabolism may be one factor that contributes t o the gender disparity in drug-related torsades de pointes. It is know n that hypothyroidism may promote QT prolongation and torsades de poin tes(7) and that women are more likely to develop hypothyroidism, both overt(8) and subclinical.(9) We therefore undertook a systematic searc h for possible evidence of hypothyroidism in patients with drug-associ ated torsades de pointes.