Patients with ischemic cardiomyopathy (left ventricular ejection fraction <35%) and heart failure who already have an implantable device with an atrial lead (dual chamber defibrillator or biventricular defibrillator) will undergo sequentially 1. Sham low level tragus stimulation (LLTS) (5min), 2. Active LLTS at 5Hz (15min) and 20Hz (15min) and 3. Active LLTS group with atrial pacing at 100bpm at 5Hz (15min) and 20Hz (15min). The latter is required to examine the effect of LLTS on RA independent of heart rate. Repolarization alternans will be measured by analyzing a regular 12-lead ECG using a custom-made software.

Inclusion Criteria:

1. Ischemic cardiomyopathy (LVEF <35%) and heart failure
2. Implantable device with an atrial lead (dual chamber ICD or CRT-D)
3. Sinus rhythm at the time of the study

Exclusion Criteria:

1. Recent (<6 months) stroke or myocardial infarction
2. Persistent atrial fibrillation
3. Recurrent vaso-vagal syncopal episodes
4. Unilateral or bilateral vagotomy
5. Pregnancy or breast feeding
6. Uncontrolled diabetes or hypertension
7. Sick sinus syndrome and 2nd or 3rd degree AV block (without a pacemaker)
8. Bifascicular block or prolonged first degree block
9. Hypotension due to autonomic dysfunction
10. Inability or unwillingness to understand and/or sign informed consent