Changes in Electrocardiogram Findings during Treatment with Gonadotropin-Releasing Hormone Agonist and Surgical Castration for Prostate Carcinoma

Abstract

Purpose: To investigate electrocardiogram (ECG) changes after complete androgen blockade (CAB) achieved by either surgical or medical castration and compare the outcomes of the groups. Methods: Sixty-three consecutive men (between 58 - 86 years of age) requiring CAB for prostate cancer were enrolled in the study. Patients with diabetes mellitus, an additional malignancy, coronary heart disease, atrial fibrillation, heart failure or a medical history of cardiac event in the last 12 months were excluded from the study. Additionally, those who were taking medicine affecting heart rate were excluded. The participants were divided into two groups according to their modality of castration. The first group consisted of 35 patients who received bilateral orchiectomy plus anti-androgen medication. The second group contained 28 patients who accepted gonadotropin-releasing hormone (GnRH) plus anti-androgen therapy. After complete examinations and biochemical tests, the ECG leads of the patients were obtained conveniently. This was then repeated at three- and six-month visits. ECG findings (including heart rate, PR, QRS, QT, corrected QT (QTc) intervals and QT dispersion (QTd)) were recorded and analysed statistically. The groups were then compared in terms of pre- and post-treatment ECG outcomes. Results: Both groups revealed similarly lower heart rate and prolonged PR, QRS, QT, corrected QTc and QTd by the end of six months. By the end of three months, all variables had changed significantly in the orchiectomy group, whereas in the GnRH group, they had not. Conclusion: CAB may result in lower heart rate and prolonged QT, a condition associated with fatal cardiac arrhythmia and sudden death. Therefore, patients receiving CAB should be monitored closely for cardiac adverse effects.