The study is a randomized controlled pilot trial to evaluate whether withdrawal of spironolactone is safe and associated with re-deterioration of left ventricular function in patients with heart failure with improved ejection fraction. The aim of current trial is to test the hypothesis that withdrawal of spironolactone would not be associated with relapse of significant clinical deterioration of left ventricular systolic function.

Inclusion Criteria:

• Willing and capable of providing informed consent and agrees to follow the study protocol and schedule of clinical follow-up
• Age between 19 and 80 years old
• Prior diagnosis of heart failure with reduced left ventricular ejection fraction (LV EF ≤ 35%) and on medical therapy including spironolactone combined with angiotensin-converting enzyme or angiotensin receptor blocker or antiotensin receptior neprilysin blocker, beta-blocker.
• LV EF ≥ 50% documented with echocardiography performed within a month
• Documented result of BNP or NT-proBNP level within a month

Exclusion Criteria:

• Dyspnea ≥ New York Heart Association (NYHA) functional class III
• Patients who need to discontinue spironolactone owing to prior adverse event
• Primary valvular heart disease with at least moderate degree
• Estimated glomerular filtration rate less than 30 mL/min per 1.73 m2
• Uncontrolled hypertension defined as blood pressure more than 140/90 mmHg
• Presence of other clinical reason to continue spironolactone such as myocardial infarction, primary aldosteronism, and liver cirrhosis
• Hyperkalemia defined as serum potassium level less than 3.5 mmol per liter
• Pregnant and/or lactating women
• Life expectancy less than a year
• Patients who are not suitable to enrollment by investigator's discretion