A Prospective, Single-center, Open-label, Pilot Study to Compare the Effectiveness and Safety of Diuretics Add-On Strategy in Chronic Heart Failure Patients (DIOS 1)

Inclusion Criteria: 1. dyspnea at rest or minimal activity 2. tachypnea (respiratory rate \> 20/min) or rales or pulmonary edema on chest X-ray 3. who need diuretics add over 40mg of daily furosemide dose Exclusion Criteria: 1. Hospitalization for acute heart failure decompensation 2. cardiogenic shock (Systolic Blood Pressure \< 80mmHg) 3. Need or plan for renal replacement therapy (dialysis, kidney transplant) 4. serum creatine level \> 2.5mg/dl 5. serum potassium (K+) \> 5.5mg/dl 6. daily spironolactone dose \> 50mg 7. previous thiazide or metolazone user 8. Age \> 75 years old or poor compliance patients 9. allergy, adverse drug reaction, hypersensitivity to any kinds of diuretics 10. life expectancy \< 6 months (e.g. metastatic malignancy, liver cirrhosis) 11. pregnancy or women at age of childbearing potential