Chest pain is one of the most common reasons people seek medical advice. Traditionally, doctors have associated angina with narrowing or blockage of the large coronary arteries that supply blood to the heart muscle. However, many patients experience typical angina symptoms despite having coronary angiograms (either traditional invasive procedure or CT Coronary Angiograms) that show little or no significant blockage.

For years, these patients were sometimes reassured that their coronary arteries were “normal.” We now know that many of them have a genuine cardiovascular condition called microvascular angina (MVA), also known as coronary microvascular dysfunction (CMD).

Microvascular angina occurs when the tiny blood vessels within the heart—the coronary microcirculation—do not function properly. These vessels are too small to be seen on a standard coronary angiogram, yet they play a crucial role in regulating blood flow to the heart muscle. When they fail to dilate appropriately or become excessively constricted, the heart may not receive enough oxygen-rich blood, resulting in chest pain, breathlessness, fatigue, and reduced exercise tolerance.

Research over the last two decades has transformed our understanding of this condition. Modern evidence shows that microvascular angina is common, particularly in women, and is associated with reduced quality of life and an increased risk of future cardiovascular events.

This article explains what microvascular angina is, why it happens, how it is diagnosed, and what current evidence tells us about treatment and prognosis.

The Heart’s Hidden Circulation

Most people think of the coronary circulation as the large arteries visible during coronary angiography. In reality, these arteries represent only a small part of the heart’s blood supply network.
The coronary circulation consists of:

• Large epicardial coronary arteries
• Pre-arterioles
• Arterioles
• Capillaries
• Venules

The smallest vessels, collectively known as the coronary microcirculation, are responsible for regulating blood flow according to the heart’s oxygen demands.

During exercise, stress, or illness, these vessels should widen dramatically to increase blood flow. In patients with microvascular angina, this response is impaired.

The result is myocardial ischaemia—insufficient oxygen delivery to heart muscle—even though the major coronary arteries appear unobstructed.

Research evidence

• Spione et al. (2022) reported that approximately 50–70% of patients undergoing coronary angiography for angina symptoms have no obstructive coronary artery disease, and coronary microvascular dysfunction may account for a substantial proportion of these cases.
• Marinescu et al. (2015) found CMD in approximately 50–65% of patients with angina and non-obstructive coronary arteries undergoing angiography.
• The ESC Working Group position paper highlighted coronary microvascular dysfunction as a major contributor to cardiovascular disease.

Why Does Microvascular Angina Occur?

Microvascular angina is not a single disease. Rather, it is a syndrome arising from several abnormalities affecting the small coronary vessels.

Endothelial Dysfunction

The endothelium is the delicate inner lining of blood vessels. It produces substances such as nitric oxide that help blood vessels relax.

When endothelial function becomes impaired:

• Vessel relaxation is reduced
  Inflammation increases
• Vasoconstriction becomes more likely
• Blood flow regulation deteriorates

Endothelial dysfunction is one of the earliest abnormalities identified in microvascular angina.

Structural Changes

Some patients develop physical changes within the microcirculation, including:

• Thickening of vessel walls
• Increased fibrosis
• Reduced capillary density
• Microvascular remodelling

These changes increase resistance to blood flow.

Abnormal Vasoconstriction

Instead of relaxing during exercise or stress, the small vessels may constrict.

This inappropriate narrowing can trigger angina symptoms despite normal-looking coronary arteries.

Inflammation

Increasing evidence suggests chronic inflammation contributes to CMD.

Inflammatory diseases associated with microvascular dysfunction include:

• Rheumatoid arthritis
• Lupus
• Psoriasis
• Systemic inflammatory disorders

Autonomic Dysfunction

The nervous system helps regulate coronary blood flow. Abnormal autonomic control may contribute to symptoms in some patients.

Who Is Most Likely to Develop Microvascular Angina?

Although microvascular angina can affect anyone, certain groups are at higher risk.

Women

Microvascular angina is particularly common in women.

The landmark Women’s Ischemia Syndrome Evaluation (WISE) studies demonstrated that many women with angina symptoms and normal coronary arteries actually had coronary microvascular dysfunction.

Hormonal changes, endothelial dysfunction, and sex-specific vascular biology are thought to contribute.

Patients with Cardiovascular Risk Factors

Risk factors include:

• High blood pressure
• Diabetes
• High cholesterol
• Smoking
• Obesity
• Sedentary lifestyle

These factors damage the endothelium and promote vascular dysfunction.

Patients with Inflammatory Conditions

Chronic inflammatory disorders are increasingly recognised as contributors to coronary microvascular disease.

Patients with Heart Failure with Preserved Ejection Fraction (HFpEF)

Emerging research links CMD with HFpEF, suggesting microvascular dysfunction may play a central role in disease development.

Research evidence

• Reis et al. (WISE Study) demonstrated a high prevalence of CMD in women with chest pain and no obstructive coronary disease. Coronary microvascular dysfunction was present in roughly 50% of women with chest pain in the absence of obstructive CAD and couldn`t be projected by the traditional risk factors for atherosclerosis and hormone levels.
• Aziz et al. identified sex-related differences in coronary vasomotor function. Women have a higher prevalence of vasomotor dysfunction (especially CMD) in comparison to men.
• Aldiwani et al. reviewed evidence linking MVA with adverse cardiovascular outcomes. Patients with MVA are at higher risk for heart attack, stroke, heart failure with preserved ejection fraction and death.
• DiGregorio et al. highlighted the role of inflammation in coronary microvascular disease.

What Are the Symptoms?

Microvascular angina can be challenging because symptoms often resemble traditional coronary artery disease.

Common symptoms include:

Chest Pain

Patients frequently describe:

• Tightness
• Pressure
• Burning
• Heaviness

Pain may occur:

• During exertion
• During emotional stress
• At rest

Breathlessness

Shortness of breath may occur even when chest pain is absent.

Fatigue

Many patients experience significant fatigue and reduced exercise capacity.

Prolonged Symptoms

Compared with classical angina, symptoms often:

• Last longer
• Occur unpredictably
• Respond less reliably to nitrates

This variability can lead to delayed diagnosis.

Why Is Diagnosis Often Delayed?

Traditional cardiology investigations focus primarily on large coronary arteries.
Patients may undergo:

• ECG
• Echocardiography
• Exercise testing
• Coronary angiography
• CT Coronary angiography

When these investigations appear normal, clinicians may incorrectly assume symptoms are non-cardiac.

Modern research has shown this assumption is often wrong.

Microvascular dysfunction cannot usually be visualised directly on routine angiography.

As a result, diagnosis frequently requires specialised testing.

How Is Microvascular Angina Diagnosed?

The diagnosis typically involves confirming symptoms of myocardial ischaemia while excluding significant obstruction of the major coronary arteries.

Coronary Angiography

This remains an important first step.

Patients often show:

• Normal coronary arteries
• Mild coronary disease
• No flow-limiting stenosis

Coronary Flow Reserve (CFR)

Coronary flow reserve measures the ability of coronary blood flow to increase when needed.

Reduced CFR suggests impaired microvascular function.

Index of Microcirculatory Resistance (IMR)

IMR provides a direct assessment of microvascular resistance.
Elevated values indicate coronary microvascular dysfunction.

Stress Cardiac MRI

Cardiac MRI has become increasingly valuable.
It can:

• Detect myocardial ischaemia
• Quantify blood flow
• Identify CMD not visible on angiography

PET Imaging

Positron emission tomography remains one of the most accurate non-invasive methods for assessing coronary microvascular function.

Invasive Coronary Function Testing, similar to Coronary Angiography

Specialised coronary function testing may include:

• Acetylcholine testing
• Adenosine testing
• Measurement of CFR
• Measurement of IMR

These tests help identify specific mechanisms responsible for symptoms.

Research evidence

• Ong et al. (COVADIS consensus) proposed international diagnostic criteria for MVA, which are easy to follow.
• Jansen et al. reviewed invasive and non-invasive assessment strategies. It highlights that invasive coronary function testing is crucial for identifying specific CMD endotypes to guide stratified, symptom-relieving medical therapy.
• The 2024 ESC Chronic Coronary Syndrome Guidelines expanded recommendations for angina and no or nonobstructive coronary artery disease (ANOCA) and ischaemia and no or nonobstructive coronary artery disease (INOCA) evaluation.
• Reynolds et al. highlighted the growing role of invasive coronary function testing.
• Presented at the AHA Scientific Sessions 2025, the landmark CorCMR trial demonstrated that stress cardiac MRI (CMR) significantly improves the diagnosis and treatment of microvascular angina compared to traditional angiography alone. By measuring blood flow, CMR changed the diagnosis for 53% of patients with chest pain and clear arteries.

Is Microvascular Angina Dangerous?

For many years microvascular angina was considered a relatively benign condition.

We now know this is incorrect.

Patients with CMD experience:

• Higher rates of hospitalisation
• Persistent symptoms
• Reduced quality of life
• Increased cardiovascular risk

Research suggests increased risks of:

• Myocardial infarction
• Stroke
• Heart failure
• Cardiovascular death

The risk is generally lower than that associated with severe obstructive coronary disease but is significantly higher than in healthy individuals.

Research evidence

• Taqueti et al. reported increased risk of heart failure with preserved ejection fraction.

Treatment of Microvascular Angina

Treatment aims to:

• Improve symptoms
• Improve quality of life
• Address cardiovascular risk factors
• Reduce long-term cardiovascular risk

Because microvascular angina has multiple causes, treatment often needs to be individualised.

Lifestyle Modification

Recommended strategies include:

• Smoking cessation
• Weight management
• Regular exercise
• Mediterranean-style diet
• Blood pressure control
• Diabetes management
• Cholesterol reduction

These interventions improve endothelial function and overall cardiovascular health.

Exercise Training

Several studies suggest structured exercise programmes improve symptoms and endothelial function.

Benefits include:

• Improved exercise capacity
• Better vascular function
• Reduced symptom burden

Statins

Statins may provide benefits beyond cholesterol reduction.

Potential effects include:

• Improved endothelial function
• Reduced inflammation
• Improved coronary flow reserve

ACE Inhibitors and ARBs

These medications can improve endothelial function and microvascular performance.

Several studies have shown improvements in symptoms and coronary physiology.

Beta Blockers

Beta blockers are often considered first-line therapy when symptoms are predominantly exercise-induced.

Potential benefits include:

• Reduced heart rate
• Lower oxygen demand
• Improved diastolic perfusion

Calcium Channel Blockers

These medications may be particularly useful when vasospasm contributes to symptoms.

Nitrates

Traditional nitrates often work less effectively in microvascular angina than in obstructive coronary disease, although some patients obtain benefit.

Ranolazine

Ranolazine has shown promise in selected patients.

Some studies demonstrate improvements in:

• Angina frequency
• Quality of life
• Exercise tolerance

Emerging Therapies

Researchers continue to investigate:

• Endothelin receptor antagonists
• Novel anti-inflammatory treatments
• Precision medicine approaches
• Mechanism-guided therapies

Research evidence

• Sucato et al. reviewed evidence supporting beta blockers, calcium channel blockers and ranolazine. The authors note that identifying distinct underlying mechanisms—such as epicardial vasospasm or microvascular dysfunction—is crucial. Traditional angiography often fails to detect these, making specialised CFT essential to tailor personalized, mechanism-based pharmacological treatments
• Smati et al. summarised contemporary clinician guidance for CMD management.
• Khandkar et al. provided an updated systematic review of therapeutic strategies. The authors highlighted:

– Some evidence quinapril and ranolazine improve coronary flow reserve versus placebo.
– Low quality evidence exogenous estrogen/progestin reduces angina.
– Further large-scale randomised trials required in this space.

The Future of Microvascular Angina Care

Microvascular angina is undergoing a major transformation in clinical practice.

Historically, patients often received limited explanations after a “normal angiogram.”

Today, the cardiology community increasingly recognises that:

• Angina can occur without major artery blockages.
• Coronary microvascular dysfunction is common.
• Symptoms are genuine and biologically explainable.
• Mechanism-specific treatment may improve outcomes.

The emergence of ANOCA (Angina with Non-Obstructive Coronary Arteries) and INOCA (Ischaemia with Non-Obstructive Coronary Arteries) frameworks has helped clinicians better understand these patients.

The 2024 ESC Chronic Coronary Syndrome Guidelines further emphasise structured investigation and targeted treatment strategies.

Advanced imaging, coronary physiology testing, and growing scientific awareness are likely to improve diagnosis rates and patient outcomes over the coming decade.

Key Messages for Patients

If you experience ongoing chest pain despite being told your coronary arteries are “normal,” do not assume the symptoms are imaginary or insignificant.

Microvascular angina is a genuine heart condition involving dysfunction of the heart’s smallest blood vessels.

Important points include:

• Symptoms are real.
• Women are particularly affected.
• Standard angiography may appear normal.
• Specialised testing may be required.
• Effective treatments are available.
• Cardiovascular risk factors remain important.
• Long-term follow-up is often appropriate.

With increasing recognition and improved diagnostic techniques, more patients are receiving accurate diagnoses and personalised treatment plans than ever before.

References

• Spione F, et al. Coronary Microvascular Angina: A State-of-the-Art Review. Front Cardiovasc Med. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9005807/
• Marinescu MA, et al. Coronary microvascular dysfunction, microvascular angina, and treatment strategies. JACC. 2015. https://pubmed.ncbi.nlm.nih.gov/25677893/
• Padro T, et al. ESC Working Group Position Paper on Coronary Microvascular Dysfunction. Cardiovasc Res. 2020. https://pmc.ncbi.nlm.nih.gov/articles/PMC7825482/
• Reis SE, et al. WISE Study. Am Heart J. 2001;141:735-741.
• Aziz A, et al. Sex-related differences in vasomotor function. J Am Coll Cardiol. 2017;70:2349-2358.
• Aldiwani H, et al. Microvascular Angina: Diagnosis and Management. 2021. https://pmc.ncbi.nlm.nih.gov/articles/PMC8674627/
• DiGregorio H, et al. Coronary microvascular dysfunction in systemic inflammatory disease. 2024. https://pubmed.ncbi.nlm.nih.gov/41033432/
• Ong P, et al. International Standardization of Diagnostic Criteria for Microvascular Angina. Int J Cardiol. 2018. https://scc.org.co/wp-content/uploads/2018/10/Internationalstandardizationofdiagnosticcriteriaformicrovascularangina.pdf
• Jansen TPJ, et al. Assessing Microvascular Dysfunction in Angina With Non-Obstructive Coronary Arteries. JACC. 2021.
• European Society of Cardiology. 2024 Chronic Coronary Syndromes Guidelines. https://www.escardio.org/guidelines/clinical-practice-guidelines/all-esc-practice-guidelines/chronic-coronary-syndromes/
• Reynolds HR, et al. Ischaemia with Non-Obstructive Coronary Arteries in the Spotlight. Eur Heart J. 2025.
• Berry C, et al. Stress MRI and Microvascular Angina. American Heart Association Scientific Sessions 2025.
• Taqueti VR, et al. Coronary Microvascular Dysfunction and Future Cardiovascular Risk.
• Sucato V, et al. The ANOCA/INOCA Dilemma Considering the 2024 ESC Guidelines. 2024.
• Smati H, et al. Coronary Microvascular Dysfunction: A Guide for Clinicians. Am J Cardiol. 2024.
• Khandkar C, et al. Updated Review on Therapeutic Strategies in CMD. 2025.

Written with assistance of AI, checked by Dr Bart Olechowski for accuracy.