Changes of Left Ventricular Mass and Cardiac Function in Patients With Active Acromegaly During Treatment With the Growth Hormone Receptor Antagonist Pegvisomant

Inclusion Criteria: * Active acromegaly in adult subjects (≥ 18 years) after surgery and/or radiation therapy with elevated IGF-1 levels despite treatment with somatostatin analogues or dopamine agonists * Pegvisomant therapy is indicated (i. e. patients who have had an inadequate response to surgery and/or radiation therapy and/or other medical therapy, or for whom these therapies are not appropriate) * Evidence of left ventricular hypertrophy (infero-lateral wall thickness ≥ 12 mm assessed by echocardiography) or * Evidence of impaired diastolic function (≥ stage 2 as assessed by echocardiography) or * Evidence of systolic dysfunction (Ejection fraction \< 50% assessed by echocardiography) * Stable medication for arterial hypertension and heart failure for 3 months * Written informed consent. Exclusion Criteria: * Pregnancy and lactation period * Previous therapy with Pegvisomant * Suspected or known hypersensitivity to the drug or any of its components * Contraindications for MRI * History of malignancy during the last 5 years * Suspected or known drug or alcohol abuse * Patients who are neither able to self administer study medication on a daily basis nor have a caregiver who can administer study medication to the patient on a daily basis * Any condition which in the opinion of the investigator makes the patient unsuitable for inclusion * Participation in another clinical trial * Pituitary adenoma with a distance to the optic chiasm of \< 3 mm * Any other drug for treatment of acromegaly (e.g. dopamine agonists, Somatostatin analogues) which would be necessary during the study or patients who apply for radiotherapy * Instable heart insufficiency classified as NYHA IV. * Severe renal insufficiency, liver transplantation