title: Results of comprehensive diagnostic work-up in 'idiopathic' dilated cardiomyopathy.
abstract: Dilated cardiomyopathy (DCM) is characterised by left ventricular dilation and dysfunction not caused by coronary disease, valvular disease or hypertension. Owing to the considerable aetiological and prognostic heterogeneity in DCM, an extensive diagnostic work-up is recommended. We aimed to assess the value of diagnostic testing beyond careful physical examination, blood tests, echocardiography and coronary angiography.
  
  
  
  From October 2008 to November 2012, we prospectively recruited 102 patients referred to our tertiary care hospital with a diagnosis of 'idiopathic' DCM based on patient history, physical examination, routine blood tests, echocardiography and coronary angiography. Extended work-up included cardiac MRI, exercise testing, right-sided catheterisation with biopsies, 24 h ECG and genetic testing.
  
  
  
  In 15 patients (15%), a diagnosis other than 'idiopathic' DCM was made based on additional tests. In 10 patients (10%), a possibly disease-causing mutation was detected. 2 patients were found to have non-compaction cardiomyopathy based on MRI findings; 2 patients had systemic inflammatory disease with cardiac involvement; and in 1 patient, cardiac amyloidosis was diagnosed by endomyocardial biopsy. Only in 5 cases did the results of the extended work-up have direct therapeutic consequences.
  
  
  
  In patients with DCM, in whom patient history and routine work-up carry no clues to the aetiology, the diagnostic and therapeutic yield of extensive additional testing is modest.
authors.affiliation: Department of Cardiology , Oslo University Hospital Rikshospitalet , Oslo , Norway ; Faculty of Medicine , K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo , Oslo , Norway.
authors.forename: Kaspar
authors.initials: K
authors.lastname: Broch
authors.affiliation: Department of Cardiology , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Arne K
authors.initials: AK
authors.lastname: Andreassen
authors.affiliation: Department of Radiology and Nuclear Medicine , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Einar
authors.initials: E
authors.lastname: Hopp
authors.affiliation: Department of Medical Genetics , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Trond P
authors.initials: TP
authors.lastname: Leren
authors.affiliation: Institute of Pathology , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Helge
authors.initials: H
authors.lastname: Scott
authors.affiliation: Department of Microbiology , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Müller
authors.affiliation: Department of Cardiology , Oslo University Hospital Rikshospitalet , Oslo , Norway.
authors.forename: Svend
authors.initials: S
authors.lastname: Aakhus
authors.affiliation: Department of Cardiology , Oslo University Hospital Rikshospitalet , Oslo , Norway ; Faculty of Medicine , K.G. Jebsen Cardiac Research Centre and Center for Heart Failure Research, University of Oslo , Oslo , Norway.
authors.forename: Lars
authors.initials: L
authors.lastname: Gullestad
keywords: GENETICS; HEART FAILURE; IMAGING AND DIAGNOSTICS