Zoledronic acid and atrial fibrillation in cancer patients

Treatment with a bisphosphonate was found to be associated with a significantly increased risk for atrial fibrillation (AF) in a few studies. A recent study showed that once-yearly infusions of intravenous zoledronic acid (ZA) significantly increased the risk of serious AF in postmenopausal women with osteoporosis. This study was conducted to determine the frequency of atrial fibrillation among cancer patients receiving the standard treatment of ZA. Patients with bone metastases who presented to our outpatient clinic for any reason (routine control, chemotherapy, or ZA administration) were included in the study. All patients had been receiving 4 mg ZA at 4-week intervals, with each dose administered over 15 min. A short survey was completed and standard 12-lead ECG recordings were obtained. One hundred and twenty-four cancer patients with documented bone metastases were evaluated. Mean age of the patients was 55 +/- 13.0 years, 60% of the patients were female. Forty-one percent of the patients had breast cancer, 18% had non-small cell lung cancer, and the remainder had other solid tumors. Mean duration of ZA administration was 13.4 +/- 15.0 months. Mean total cumulative dose was 54 +/- 15.0 mg per patient. Sixty patients (48%) had previously been treated with anthracycline-containing regimens, and 37 (30%) had received chest radiotherapy that might affect the heart. Twenty-three percent of the patients had hypertension, 10% had diabetes mellitus, 3.7% had myocardial infarction history, 1.9% had congestive heart failure, and 1% had valvular disease; 10.5% were current smokers and 32% ex-smokers. On ECG evaluation, we observed normal sinus rhythm in 58%, sinus tachycardia in 15%, sinus bradicardia in 3.2%, and ventricular extrasystole in 5.7% of the patients. There was no AF in any of the cases. There was no increase in the risk of AF frequency in cancer patients who were treated with intravenous ZA, although most of the patients had additional risk factors including previous treatment with cardiotoxic agents or with chest radiotherapy. We believe that the risk of AF is negligible in this patient population and does not affect treatment decisions.