ACE and heart failure: The difference between the surgery sample and the non-surgery sample is statistically significant in the following variables: age, gender, level of medical institutions, regional distribution, whether comorbid with high blood pressure or heart failure or diabetes, whether combine medication with beta blockers or nitrate esters or angiotensin converting enzyme inhibitors (ACEI) or angiotensin receptor blockers (ARB) or antiplatelet/thrombolytic/anticoagulant or lipid-regulating drugs.