Does subclinical hypothyroidism explain the increased susceptibility of women to torsades de pointes?

Among 20 consecutive patients (65% women) with drug-associated torsades de pointes, chemical evidence for hypothyroidism was found in only 10% of both women and men. Subclinical hypothyroidism is therefore unlikely to account for the consistently observed sex difference in the propensity to torsades de pointes.

Age-gender influence on the rate-corrected QT interval and the QT-heart rate relation in families with genotypically characterized long QT syndrome.

Objectives: We sought to analyze age-gender differences in the rate-corrected QT (QTc) interval in the presence of a QT-prolonging gene.

Background: Compared with men, women exhibit a longer QTc interval and an increased propensity toward torsade de pointes. In normal subjects, the QTc gender difference reflects QTc interval shortening in men during adolescence.

Probucol-associated tachyarrhythmic events and QT prolongation: importance of gender.

From published articles and adverse reactions reports filed with the FDA (available through the Freedom of Information Act), we analyzed occurrences of tachyarrhythmias and the magnitude of QTc prolongation associated with probucol therapy. Of 16 cases of tachyarrhythmic events reported in association with probucol, 15 (94%) occurred in women (p < 0.01 vs expected value of 58%).

T wave "humps" as a potential electrocardiographic marker of the long QT syndrome.

Objectives: This study attempted to determine the prevalence and electrocardiographic (ECG) lead distribution of T wave "humps" (T2, after an initial T wave peak, T1) among families with long QT syndrome and control subjects.

Background: T wave abnormalities have been suggested as another facet of familial long QT syndrome, in addition to prolongation of the rate-corrected QT interval (QTc), that might aid in the diagnosis of affected subjects.

Methods: The ECGs from 254 members of 13 families with long QT syndrome (each with two to four generations of affected members) and from 2,948 healthy control subjects (age > or = 16 years, QTc interval 0.

Routine withholding of digitalis for heart rate below 60 beats per minute: widespread nursing misconceptions.

Objective: To describe the nursing practice of withholding digitalis solely on the basis of a heart rate less than 60 beats/min and to determine the rationale for this practice.

Design: Non-randomized survey.

Setting: Five hospitals in a midwestern metropolitan area, ranging from affiliates of a university medical center to a private community-based hospital.