Labo (FSS, Na, K, BNP, urea, creatinine, AST, ALT, GGT, troponin, glucose)
BNP is usually> 400pg / ml in patients with heart failure. If <100 pg / mL, consider an alternative diagnosis - Non-invasive test for ischemia, coronary angiography).
Search for arrhythmia (ECG, Holter, ET)
Search for alcohol or drugs.
Drug review (chemotherapy, antidepressants, phenothiazines, anti TNF).