Implantable cardioverter-defibrillator (ICD) therapy reduces mortality in patients with chronic heart failure and reduced left ventricular ejection fraction (LVEF) <36%. Nevertheless, patient selection for ICD therapy based on LVEF and NYHA functional class alone seems to have a low specificity and sensitivity: In 100 patients treated, the SCD-HeFT study prevented 7 deaths in 5 years. Therefore 93 patients have a risk of adverse effects, such as operation risk, infection, pneumothorax, lead dislocation, and inadequate icd therapy. On the other hand, patients with advanced or end stage heart failure might rather die off progressive heart failure death and thus not benefit from ICD therapy.

It therefore seems appropriate and necessary to improve the individualized risk stratification in these patients. The aim of this study is to evaluate multiple cardiac biomarkers in a model predicting ventricular arrhythmias in patients on ICD therapy.

Patients having or getting an ICD in the Dept. of Cardiovascular Medicine of the Hannover Medical School will be recruited in the next 2 years. Blood samples of all patients will be obtained at inclusion and at 6 months follow-up. Patients will be followed-up for 1-2 years after inclusion.

Inclusion Criteria:

• Patient meeting the current indications for primary or secondary prophylactic ICD/CRT-D therapy
• age 18 years or older

Exclusion Criteria:

• Patient unwilling to participate.

Patients reveicing or having received an implantable cardioverster-defibrillator in the Dept. of Cardiovascular Medicine of the Hanover Medical School.