Previous studies have shown high proportions of vitamin D deficiency among elderly in Denmark. Vitamin D is important for muscular function. The investigators intend to examine if it is possible to improve cardiovascular function in patients with heart failure and vitamin D deficiency by supplementation with vitamin D.

Heart failure (HF) is a major course of morbidity and mortality. The prevalence in the Danish population is 1-2% and for age 50 -75 years: 2-3% (1) . It has been estimated that there are currently 6.5 million HF patients in Europe and 5 million in the USA (2) . Lack of vitamin D has been linked to heart disease including ischemic heart disease, heart failure, and hypertension.(3) Vitamin D deficiency is prevalent in the elderly population. Calcium absorption, bone mineralization and muscle function may be impaired. Vitamin D receptors have also been demonstrated in skeletal as well as cardiac muscle(4) . Vitamin D and Parathyroid Hormone (PTH) are closely linked in the calcium metabolic system. In order to maintain serum calcium within range PTH and vitamin D acts together in response to changes in serum-calcium levels. 25(OH)D concentration also being an important factor determining the levels of PTH.(5) Decreasing vitamin D leads to increasing levels of PTH. Hyperparathyroidism in patients with kidney-disease has in numerous studies been linked to cardiovascular disease, left ventricle hypertrophy, and valvular calcification .(6) Aim: Intervention with vitamin D and calcium will improve patients' vitamin D levels and suppress PTH. Thus we hope to find an improved cardiac function and quality of life in the intervention-group.

Comparison: Cardiac function (and other effect parameters - such as self-evaluated health) in the intervention group vs. in the placebo-group

Inclusion Criteria:

• Over 18 years of age
• Vitamin D (serum 25-OHD): 50nmol/l or less
• Heart failure (EF 40% or less, NYHA:2 or more)

Exclusion Criteria:

• Calcium metabolic disturbances
• Granulomatous diseases
• Alcohol or drug abuse
• Intake of 400IU (or more) vitamin D/day
• Condition too poor to participate
• Pregnancy
• AF with HF 90 or above
• Mitral insufficiency, degree 3 or above
• Large cardiac aneurisms
• Significant aorta stenosis
• Significant aorta insufficiency
• Allergy to components