Evolution of Electrocardiographic Repolarization Parameters During Antiandrogen Therapy in Patients with Prostate Cancer and Hypogonadism

We assessed the effects of antiandrogen therapy on ECG parameters of ventricular repolarization related to arrhythmic risk in 35 patients aged 70.3 +/- 7 years with advanced prostate cancer treated with degarelix associated with enzalutamide (group A, 26 patients) or degarelix monotherapy (group B, 9 patients). We analyzed Fridericia corrected Q-T interval (QTc), Q-T dispersion (QTd), J-Tpeak interval (JTp), mean and maximum Tpeak-Tend interval (Tpe) and Tpe/QT ratio, Tpeak-Tend dispersion (Tped), index of cardio-electrophysiological balance (iCEB) from ECG tracings, and occurrence of ventricular premature beats (VPB) recorded by Holter ECG, before initiation of medication (M0) and after 6 months of treatment (M1). The groups had similar demographics except for a higher prevalence of prior myocardial infarction in group B (p = 0.01). All patients had low serum testosterone at M1. Baseline QTc, QTd, maxTpe/QT, meanTpe, maxTpe, Tped values were higher in B compared to A. They had a significant prolongation at M1 only in A. 20 patients in A and 6 in B had a 10% prolongation or decrease of iCEB (p = 0.66). In 5 patients, VPB severity increased from non-complex to complex: 3 in A and 2 in B (p = 0.31), but no sustained ventricular arrhythmia was registered. In conclusion, after 6 months of treatment, patients with hypogonadism on degarelix associated with enzalutamide had significant prolongation of QTc, QTd, maxTpe, meanTpe/QT, maxTpe/QT, Tped compared to patients on degarelix alone. The proportion of patients with 10% iCEB variation was similar between groups. There was no record of severe arrhythmias during the first 6 months of treatment.