In clinical practice, Class A antihypertensive drugs refer to ACEI antihypertensive drugs, also known as angiotensin-converting enzyme inhibitors, which are first-line antihypertensive drugs. In addition to lowering blood pressure, this type of drug can help reduce proteinuria and delay renal impairment, and is also used as a secondary prevention drug for patients with angina and heart failure. This drug is currently widely used in clinical practice because it has a very good secondary prevention effect and is very suitable for patients with diabetes mellitus with hypertension.