Heart

OBJECTIVE: A prolonged QTc (LQT) is a surrogate for the risk of torsade de pointes (TdP). QTc interval duration is influenced by sex hormones: oestradiol prolongs and testosterone shortens QTc. Drugs used in the treatment of breast cancer have divergent effects on hormonal status. METHODS: We performed a disproportionality analysis using the European database of suspected adverse drug reaction (ADR) reports to evaluate the reporting OR (ROR chi(2)) of LQT, TdP and ventricular arrhythmias associated with selective oestrogen receptor modulators (SERMs: tamoxifen and toremifene) as opposed to aromatase inhibitors (AIs: anastrozole, exemestane and letrozole). When the proportion of an ADR is greater in patients exposed to a drug (SERMs) compared with patients exposed to control drug (AIs), this suggests an association between the specific drug and the reaction and is a potential signal for safety. Clinical and demographic characterisation of patients with SERMs-induced LQT and ventricular arrhythmias was performed. RESULTS: SERMs were associated with higher proportion of LQT reports versus AIs (26/8318 vs 11/14851, ROR: 4.2 (2.11-8.55), p