TREATMENT WITH GROWTH HORMONE RECEPTOR ANTAGONIST IN ACROMEGALY: EFFECT ON CARDIAC ARRHYTHMIAS.

OBJECTIVE: to evaluate the effects of short and long-term treatment with pegvisomant (PEG) on arrhythmias in acromegalic patients resistant to long-term high-dose therapy with somatostatin analogues (SA). PATIENTS AND METHODS: thirteen patients entered the study. All patients started PEG at initial dose of 10 mg daily, then titrated of 5 mg every 6 weeks on the basis of IGF-I. A standard 24-h ECG registration was performed in all patients at baseline and after 6 and 18 months of PEG to evaluate: mean (HR), maximum (MHR) and minimum (mHR) heart rate, pauses number (P) and duration (PD), supraventricular episodes number (SE) and duration (SED), ventricular ectopic beats number (EB) and duration (EBD). Left ventricular mass (LVM) was also evaluated by standard echocardiography RESULTS: A slight but not significant decrease in HR, MHR and mHR was observed after 6-month PEG, whereas a significant decrease in HR (p=0.03), MHR (p=0.05) and mHR (p=0.05) was found after 18-month PEG compared to baseline. LVM significantly (p=0.05) correlated with MRH (r= -0.50) after short-term treatment, and with HR (r= -0.54) and mHR (r= -0.55) after long-term treatment. Long-term PEG induced the complete recover of arrhythmias recorded at baseline in one patient and the improvement of rhythm disorders developed after 6-month therapy in another patient. The prevalence of conduction disturbances passed from 15% to 7.7% after long-term PEG. CONCLUSIONS: Long-term treatment with PEG reduces HR, MHR and mHR and improves rhythm abnormalities in acromegaly