How do ACE inhibitors help the heart? A Comprehensive Guide

October 11, 2025 •

4 min read

In the United States, nearly half of adults (48.1%) have high blood pressure, a major risk factor for heart disease [1.6.2]. Understanding how do ACE inhibitors help the heart? is key, as they are a first-line therapy for managing this widespread condition and protecting cardiovascular health [1.3.6].

Quick Summary

ACE inhibitors aid the heart by blocking an enzyme that creates angiotensin II, a substance that narrows blood vessels and raises blood pressure. This action relaxes vessels, lowers pressure, and reduces the heart's workload.

Key Points

Core Function: ACE inhibitors work by blocking the enzyme that produces angiotensin II, a hormone that constricts blood vessels and raises blood pressure [1.2.1, 1.2.3].
Reduced Workload: By relaxing blood vessels and reducing fluid retention, they lower the heart's afterload and preload, making it easier for the heart to pump blood [1.3.6, 1.2.5].
Primary Treatments: They are first-line therapy for hypertension and are crucial in managing heart failure, post-heart attack care, and protecting kidney function [1.3.1, 1.3.6].
Common Side Effect: A persistent, dry cough is the most characteristic side effect, occurring in up to 20% of patients [1.3.1].
Long-Term Benefits: Proven to reduce mortality in patients with heart failure and post-myocardial infarction, and to slow the progression of heart disease [1.8.1, 1.8.4].
Potassium Monitoring: ACE inhibitors can increase potassium levels in the blood, so potassium intake and supplements should be monitored [1.7.1, 1.7.2].
Key Difference from ARBs: Unlike ARBs, which block angiotensin II receptors, ACE inhibitors block its production; this difference explains why ACE inhibitors are more likely to cause a cough [1.2.4, 1.5.2].

The Core Mechanism: Blocking the Angiotensin-Converting Enzyme

Angiotensin-converting enzyme (ACE) inhibitors are a cornerstone in cardiovascular medicine, primarily used to treat high blood pressure (hypertension) and heart failure [1.2.3]. Their function is rooted in their ability to interrupt a critical process in the body known as the Renin-Angiotensin-Aldosterone System (RAAS) [1.2.3].

The RAAS is a hormonal cascade that regulates blood pressure and fluid balance [1.2.3]. A key player in this system is a powerful hormone called angiotensin II, which has several effects that increase blood pressure:

Vasoconstriction: It narrows blood vessels, making it harder for blood to flow [1.2.1].
Aldosterone Release: It stimulates the adrenal glands to release aldosterone, a hormone that causes the kidneys to retain sodium and water. This increases the total volume of blood in the body [1.2.1, 1.2.5].

ACE inhibitors work by blocking the action of the angiotensin-converting enzyme, which is responsible for converting the inactive angiotensin I into the active angiotensin II [1.2.1, 1.2.6]. By inhibiting this conversion, ACE inhibitors lead to lower levels of angiotensin II in the bloodstream. This results in vasodilation (widening of blood vessels) and reduced aldosterone secretion, which helps the kidneys excrete more sodium and water [1.2.1, 1.2.5]. The combined effect is a lower blood pressure and a reduced workload for the heart.

How This Alleviates Strain on the Heart

By lowering blood pressure, ACE inhibitors decrease the resistance the heart has to pump against (afterload) [1.3.6]. This means the heart muscle doesn't have to work as hard to circulate blood throughout the body. Furthermore, by reducing fluid retention, they also decrease the volume of blood returning to the heart (preload) [1.2.5]. For a weakened heart, such as in patients with heart failure, this reduction in both afterload and preload is crucial. It improves the heart's efficiency, increases cardiac output, and can slow down the progression of heart disease [1.3.6, 1.8.1].

Key Conditions Treated with ACE Inhibitors

Due to their beneficial effects on blood pressure and cardiac workload, ACE inhibitors are prescribed for a variety of conditions:

Hypertension (High Blood Pressure): They are often a first-line therapy, used alone or with other medications like diuretics, to control blood pressure [1.3.1, 1.3.6].
Heart Failure: They are a standard treatment for patients with heart failure with reduced ejection fraction (HFrEF), as they improve symptoms, reduce hospitalizations, and prolong survival [1.3.1, 1.8.1].
Post-Myocardial Infarction (Heart Attack): Administering an ACE inhibitor within 24 hours of a heart attack, especially in patients with symptoms of heart failure or a reduced ejection fraction, has been shown to reduce mortality [1.3.1, 1.8.1].
Chronic Kidney Disease: These medications can protect the kidneys, particularly in patients with diabetes or protein in the urine (proteinuria), by reducing pressure within the kidney's filtering units [1.3.1, 1.3.5].
Coronary Artery Disease: For high-risk patients, ACE inhibitors can reduce the risk of future cardiovascular events like heart attacks and strokes [1.3.3, 1.8.1].

Common ACE Inhibitors and Side Effects

Many ACE inhibitors are available, and their generic names typically end in "-pril" [1.2.1]. Common examples include:

Lisinopril (Zestril, Prinivil) [1.3.3]
Enalapril (Vasotec) [1.3.3]
Ramipril (Altace) [1.3.3]
Benazepril (Lotensin) [1.3.3]

While generally safe and effective, ACE inhibitors can have side effects. The most noted is a persistent, dry cough, which occurs in up to 20% of patients and is thought to be caused by the accumulation of bradykinin, a substance that ACE normally breaks down [1.3.1, 1.2.1]. Other potential side effects include dizziness, headache, fatigue, and elevated potassium levels (hyperkalemia) [1.4.1, 1.4.6]. A rare but serious side effect is angioedema, a rapid swelling of the lips, tongue, and throat that can be life-threatening [1.2.1, 1.2.5].

ACE Inhibitors vs. ARBs: A Comparison

Angiotensin II Receptor Blockers (ARBs) are another class of drugs that act on the RAAS. While ACE inhibitors block the production of angiotensin II, ARBs prevent angiotensin II from binding to its receptors [1.2.4]. Both classes effectively lower blood pressure, but they have different side effect profiles. ARBs do not cause the characteristic dry cough associated with ACE inhibitors and have a lower risk of angioedema [1.5.2, 1.5.3].


Feature	ACE Inhibitors	Angiotensin II Receptor Blockers (ARBs)
Mechanism	Block the production of angiotensin II [1.2.1]	Block angiotensin II from binding to its receptors [1.2.4]
Primary Use	Hypertension, Heart Failure, Post-MI, Kidney Protection [1.3.1]	Hypertension, Heart Failure, Kidney Protection [1.5.3]
Common Side Effects	Dry cough, dizziness, hyperkalemia [1.3.1, 1.4.1]	Dizziness, hyperkalemia [1.5.2]
Cough Incidence	Up to 20% [1.3.1]	Significantly lower than ACE inhibitors [1.5.2]
Angioedema Risk	Low, but higher than ARBs [1.2.5]	Very low [1.5.2]

Conclusion

ACE inhibitors provide critical support to the heart primarily by relaxing blood vessels and reducing blood volume, which lowers blood pressure and eases the heart's workload. This mechanism not only controls hypertension but also offers life-extending benefits for patients with heart failure and those who have suffered a heart attack [1.8.1, 1.8.4]. By preventing the long-term damage caused by high blood pressure and an overactive RAAS, these medications play a vital role in modern cardiovascular therapy. As with any medication, it is essential for patients to discuss the benefits and risks with their healthcare provider to determine the most appropriate treatment plan.

For more information from a reputable source, you can visit the American Heart Association.

Frequently Asked Questions

The main function of an ACE inhibitor is to lower blood pressure by relaxing your blood vessels and helping your body get rid of excess salt and water, which reduces the heart's workload [1.2.1, 1.2.5].

The dry cough is believed to be caused by an accumulation of a substance called bradykinin. The enzyme that ACE inhibitors block is also responsible for breaking down bradykinin, so levels of it increase and can irritate the lungs, inducing a cough reflex [1.2.1].

You should be mindful of foods high in potassium, such as bananas, oranges, potatoes, and dark leafy greens, as ACE inhibitors can cause potassium levels to rise in the blood. It's also wise to avoid high-sodium foods and salt substitutes containing potassium [1.7.1, 1.7.3, 1.7.4].

Some ACE inhibitors can begin to lower blood pressure within an hour of taking them, but their full, consistent benefit is achieved through daily, long-term use as prescribed by a healthcare provider [1.2.3, 1.7.2].

You should talk to your provider before taking nonsteroidal anti-inflammatory drugs (NSAIDs) like ibuprofen or naproxen. These medications can reduce the effectiveness of ACE inhibitors and potentially affect kidney function [1.3.2, 1.7.2].

No, they are different classes of medication. ACE inhibitors block the production of angiotensin II, while Angiotensin II Receptor Blockers (ARBs) prevent angiotensin II from acting on its receptors. ARBs are often prescribed as an alternative if a patient cannot tolerate the cough from an ACE inhibitor [1.2.4, 1.6.0].

ACE inhibitors are contraindicated during pregnancy due to the risk of fetal injury. They should also be avoided by individuals with a history of angioedema (allergic swelling) or those with certain types of severe kidney disease like bilateral renal artery stenosis [1.2.1, 1.7.2, 1.2.5].