The aim of this randomized controlled study is to investigate the effect of continues positive airway pressure (CPAP) treatment in patients with dilated cardiomyopathy (DCM) and concomitant obstructive sleep apnea (OSA). The primary endpoint is left ventricular function measured by magnetic resonance (improvement of at least 4%) after six months treatment with CPAP.

The secondary endpoints include diastolic dysfunction, cardiovascular biomarkers and quality of life.

Sleep apnea, either obstructive (OSA) and central (CSA), occurs in more than half of all patients with heart failure (HF), and is associated with poor prognosis in these individuals.

Dilated cardiomyopathy (DCM) is the most common type of cardiomyopathy and is defined as the presence of the left ventricle dilatation and left ventricular systolic dysfunction without concurrent valvular or coronary artery disease. Its etiology is unclear, but a genetic component is present in at least 25% of cases. In younger individuals, the etiology is more heterogeneous, where a rare type of cardiomyopathy may occur in women in connection with pregnancy, s.c. peripartum cardiomyopathy. Other underlying causes include alcohol, drugs, pharmaceuticals, endocrine disorders, systemic diseases and general muscle. These factors account for approximately half the cases of DCM in younger and other half designated as idiopathic (IDCM).

The relationship between cardiomyopathies and OSA is insufficiently studied so far. In a smaller population of 20 individuals with DCM, sleep apnea (OSA or CSA) had 16, ie 80% of patients. The first-line treatment of OSA is continues positive pressure breathing mask (CPAP) during sleep in patients with daytime sleepiness. Effect of CPAP therapy in patients with DCM and OSA is completely unknown, because many of them do not report daytime sleepiness. The fact that patients with heart failure and reduced pumping function usually have symptoms of including fatigue, it becomes difficult to distinguish what is fatigue due to heart failure and what is related to sleep apnea. Interpretation of the Epworth Sleepiness Scale (ESS) is thus difficult and possibly unsure why all patients with DCM and OSA will be randomized to treatment with CPAP.

Inclusion Criteria:

Patients with newly diagnosed or previously known DCM, treated and followed at cardiology outpatients clinic, stable in their symptoms and functional class at least 2 weeks after the last medicine change.

• Consent for the study.
• EF ≤ 45%.
• OSA diagnosis (Apnea-Hypopnea index> = 15 in the sleep recording below).

Exclusion Criteria:

• Patients already treated with Continues Positive Airway Pressure.
• Patients with claustrophobia