ANOCA: Angina with Normal Coronary Arteries , Understanding the New Diagnosis

ANOCA (Angina with Non-Obstructive Coronary Arteries) is a clinical syndrome affecting 3 to 4 million American women who experience genuine cardiac chest pain despite coronary arteries showing less than 50% stenosis on angiography. The 2020 EAPCI Expert Consensus Document established ANOCA as a diagnostic framework encompassing vasospastic angina and microvascular angina, conditions previously dismissed as non-cardiac. Women with ANOCA face a 2.5-fold increased risk of major adverse cardiovascular events compared to truly normal controls, yet up to 75% remain untreated because standard cardiac evaluation stops at the angiogram.

The Name Changed. The Disease Always Existed.

The term ANOCA was not in her cardiologist’s training. But the condition she had been living with for four years very much existed. The nomenclature changed. The disease always was real.

She was 52 when the chest pain started. Pressure behind the sternum. Radiating to her jaw. Worse with stress, better with rest. Classic angina by every textbook definition. Her stress test showed ST-segment depression. Her cardiologist scheduled an angiogram.

The catheterization took forty minutes. The images showed coronary arteries with mild wall irregularities but no significant narrowing. Less than 30% stenosis anywhere. Her cardiologist walked into the recovery room with good news. Your arteries are clear. This is not your heartirtual.

She asked what was causing the pain. He suggested anxiety. Perhaps acid reflux. Maybe hormonal changes from perimenopause. She should see her primary care physician.

For the next four years, she saw seven specialists. She underwent two more stress tests, an echocardiogram, a CT angiogram, and a 48-hour Holter monitor. She tried three different antidepressants, two proton pump inhibitors, and estrogen replacement therapy. The chest pain continued. Some days it woke her at 3 AM. Some days it struck during her commute. She began declining social invitations because she never knew when an episode would hit.

In 2023, she found an article about INOCA and ANOCA. She printed it. She brought it to a new cardiologist at an academic medical center. That cardiologist ordered functional coronary testing during a repeat catheterization. Her Coronary Flow Reserve was 1.8. Her Index of Microvascular Resistance was 34. Both numbers were pathologically abnormal.

She had microvascular angina. Her heart was sick. It had been sick the entire time. The disease did not change. The diagnostic framework finally caught up.

What ANOCA Actually Means

ANOCA is defined as angina or angina-equivalent symptoms in patients whose coronary angiography shows less than 50% diameter stenosis in any major epicardial vessel. This is not the absence of disease. This is disease that standard angiography cannot visualize. Kunadian 2020

The framework recognizes two primary pathophysiological subtypes.

Coronary Vasospastic Angina occurs when epicardial arteries that appear normal at rest undergo inappropriate constriction. The spasm can reduce blood flow by 90% or more. It often strikes at rest, particularly between midnight and early morning. Smoking, cocaine, and certain medications trigger episodes. But many patients have no identifiable trigger.

Microvascular Angina involves dysfunction of the small resistance vessels that angiography cannot image. These vessels are 100 to 500 micrometers in diameter. They regulate 70% of coronary vascular resistance. When they fail to dilate appropriately during demand, the heart muscle becomes ischemic despite open epicardial arteries.

Some patients have both mechanisms simultaneously. The subtypes require different diagnostic tests and different treatments. Treating vasospastic angina with beta-blockers can worsen symptoms. Treating microvascular angina with nitrates alone often fails. The diagnosis must specify the mechanism. 5 / Solid

The prevalence is staggering. In the WISE study, 62% of women referred for coronary angiography for suspected ischemia had no obstructive CAD. Bairey Merz 2006 Population estimates suggest 3 to 4 million American women have ANOCA. Most have never heard the term. Most have been told their hearts are fine.

The Diagnostic Failure

Standard cardiac evaluation is designed to find obstructive coronary artery disease. It looks for plaques that narrow the arterial lumen by more than 70%. When it finds them, cardiologists can stent or bypass them. This model works for the typical male presentation of coronary disease.

It fails catastrophically for ANOCA.

A stress echocardiogram has approximately 40% sensitivity for microvascular disease in women. This means it misses more patients than it catches. A nuclear stress test performs slightly better at 50 to 60% sensitivity. But both tests are optimized for detecting regional wall motion abnormalities from epicardial stenoses. Diffuse microvascular ischemia produces global dysfunction that these tests interpret as normal. Taqueti 2017

Standard coronary angiography visualizes vessels down to approximately 500 micrometers. The microcirculation that causes microvascular angina is invisible. A cardiologist can perform a technically perfect angiogram and correctly report no obstructive disease while completely missing the mechanism causing the patient’s symptoms.

I call this the Angiographic Blindspot Phenomenon. The test answers the question it was designed to answer. Are there blockages greater than 70%? No. The test cannot answer the question the patient is asking. Why does my chest hurt?

The 2020 EAPCI Expert Consensus Document established that standard angiography is insufficient to exclude coronary vascular dysfunction. Kunadian 2020 Functional coronary testing during catheterization is required for definitive diagnosis. This testing adds 15 to 20 minutes to the procedure. It is available at most academic medical centers. It is rarely performed at community hospitals.

The result is a diagnostic desert. Millions of women undergo angiography. Their arteries appear clear. They are told nothing is wrong. They continue to have chest pain. They continue to carry cardiovascular risk that no one is treating.

The Numbers That Make the Diagnosis

Functional coronary angiography measures what standard angiography cannot see.

Coronary Flow Reserve is the ratio of blood flow during maximal hyperemia (usually induced by adenosine infusion at 140 mcg/kg/min) to blood flow at rest. A normal CFR is greater than 2.5. This means the coronary circulation can increase flow by at least 2.5 times during demand.

A CFR less than 2.5 indicates impaired microvascular function. A CFR less than 2.0 is severely abnormal. Women with CFR less than 2.0 have a 2.5-fold increased risk of major adverse cardiovascular events including heart attack and death. Pepine 2015 5 / Solid

Index of Microvascular Resistance is measured during maximal hyperemia using a pressure-temperature sensor wire. It quantifies resistance in the microcirculation independent of epicardial disease.

An IMR of 25 units or greater indicates pathologically elevated microvascular resistance. Fearon 2003 This is the gold-standard invasive metric for diagnosing microvascular angina. It cannot be measured noninvasively. It cannot be estimated from stress testing. It requires catheterization.

Acetylcholine provocation testing diagnoses vasospastic angina. Acetylcholine is infused directly into the coronary arteries in escalating doses. In normal arteries, acetylcholine causes mild dilation. In arteries prone to vasospasm, acetylcholine triggers intense constriction.

A positive test shows greater than 90% reduction in epicardial diameter with reproduction of the patient’s typical chest pain and ischemic ECG changes. This identifies patients who will benefit from calcium channel blockers and long-acting nitrates.

The CorMicA trial demonstrated that invasive functional testing followed by stratified treatment improved symptoms and quality of life significantly compared to standard care. Ford 2018 Patients randomized to functional testing and targeted therapy had a 70% reduction in Seattle Angina Questionnaire symptom frequency scores at one year. Patients who received standard care continued to suffer.

Women don’t die from what they have. Women die from what they hold.

Treatment Matched to Mechanism

The cardinal rule of ANOCA treatment is mechanism-specific therapy. Vasospastic angina and microvascular angina respond to different medications. Using the wrong treatment worsens outcomes.

Vasospastic Angina Treatment: Calcium channel blockers are first-line therapy. Diltiazem at 180 to 360 mg daily or amlodipine at 5 to 10 mg daily reduces spasm frequency by 70 to 90% in most patients. Long-acting nitrates provide additional relief for breakthrough symptoms. Nitroglycerin sublingual tablets or spray should be carried at all times.

Beta-blockers are relatively contraindicated in pure vasospastic angina. They block beta-2 mediated vasodilation while allowing alpha-mediated vasoconstriction to predominate. This can worsen spasm. Patients with vasospastic ANOCA who have been placed on beta-blockers for blood pressure often report worsening symptoms.

Smoking cessation is mandatory. Smoking increases vasospasm frequency five-fold. Cocaine must be avoided permanently. Even a single use can trigger fatal spasm in susceptible patients.

Microvascular Angina Treatment: Beta-blockers are first-line for microvascular angina, the opposite of vasospastic angina. By reducing heart rate and myocardial oxygen demand, beta-blockers decrease ischemic episodes. Metoprolol succinate at 25 to 200 mg daily or bisoprolol at 2.5 to 10 mg daily are reasonable starting points.

Ranolazine is a second-line agent with unique mechanism. It inhibits late sodium current, reducing intracellular calcium overload and improving diastolic function. The WISE-CVD substudy showed ranolazine 500 mg twice daily improved myocardial perfusion reserve in women with microvascular dysfunction.

ACE inhibitors improve endothelial function and reduce vascular inflammation. Ramipril or lisinopril at standard doses may reduce anginal episodes by 30 to 40% in patients with microvascular disease.

Statins are recommended for all ANOCA patients regardless of LDL cholesterol level. They stabilize plaque, reduce inflammation, and improve endothelial function through mechanisms independent of cholesterol lowering. High-intensity statin therapy (atorvastatin 40 to 80 mg or rosuvastatin 20 to 40 mg) is appropriate.

Mixed Phenotype Treatment: Patients with both vasospasm and microvascular dysfunction require combination therapy. Typically, a calcium channel blocker plus ranolazine, with careful beta-blocker titration if tolerated. These patients require closer follow-up and often benefit from referral to centers with coronary physiology expertise.

The Prognostic Reality

ANOCA is not a benign diagnosis. The Jespersen cohort study followed 11,223 patients with stable angina and no obstructive CAD for a median of 6.7 years. Jespersen 2012 Compared to a reference population without angina, ANOCA patients had significantly increased risk of major adverse cardiovascular events.

The hazard ratio for the composite endpoint of cardiovascular death, myocardial infarction, stroke, or heart failure hospitalization was 1.52 in women with angina and normal arteries compared to women without angina. This risk was not explained by traditional cardiovascular risk factors. The microvascular dysfunction itself carried prognostic weight.

The WISE study extended these findings with 5-year follow-up showing 16% of women with CMD (coronary microvascular dysfunction) experienced MACE compared to 7.9% of women with normal microvascular function. Bairey Merz 2006 Women with severely impaired CFR (less than 2.0) had excess cardiovascular mortality equivalent to women with obstructive coronary artery disease.

This data demolished the assumption that clear arteries mean a normal heart. ANOCA patients require risk factor modification, cardioprotective medications, and ongoing surveillance. They are not cardiac reassurance cases. They are cardiac patients. 5 / Solid

Why This Diagnosis Takes So Long

The median time from symptom onset to ANOCA diagnosis is 4 to 7 years in most case series. This delay is not patient failure. It is system failure.

First, medical education has not caught up. The 2020 EAPCI consensus document is the first major guideline to thoroughly address ANOCA. Cardiologists who completed training before 2020 received minimal education on coronary microvascular dysfunction. Many learned that normal angiography excludes cardiac disease.

Second, functional coronary testing requires equipment and expertise that many catheterization laboratories lack. Pressure-temperature sensor wires cost approximately $600 each. Adenosine and acetylcholine provocation protocols require additional time and nursing expertise. Reimbursement for functional testing has historically been lower than for percutaneous coronary intervention.

Third, the pattern recognition is wrong. Emergency departments triage chest pain based on troponin elevation and ECG changes. ANOCA patients often have negative troponins and non-diagnostic ECGs. They are discharged as non-cardiac chest pain. They return repeatedly until someone listens.

Fourth, the specialty referral pattern fails. Primary care physicians refer chest pain to cardiologists. Cardiologists order angiography. Angiography shows no obstruction. The cardiologist reports good news and closes the loop. No one orders functional testing because no one suspects functional disease.

The fix requires education, infrastructure, and incentive alignment. Academic medical centers are beginning to establish dedicated ANOCA clinics. The American Heart Association has released patient education materials. But translation to community practice will take years.

What to Bring to Your Cardiologist

The most effective patient advocacy in ANOCA is specific and documented.

Print the 2020 EAPCI Expert Consensus Document abstract. Highlight the diagnostic criteria for microvascular angina: CFR less than 2.5 or IMR greater than or equal to 25. Highlight the acetylcholine provocation criteria for vasospastic angina: greater than 90% epicardial constriction with symptom reproduction.

Request functional coronary angiography with adenosine and acetylcholine provocation if standard angiography has already shown no obstruction. Ask: “Can we measure CFR and IMR during catheterization?” Ask: “Can we perform acetylcholine provocation testing to rule out vasospasm?”

If your cardiologist is unfamiliar with these protocols, ask for referral to a center that performs invasive coronary physiology testing. Academic medical centers with cardiac catheterization fellowship programs typically have this capability. Search for physicians publishing in INOCA or ANOCA research.

Document your symptoms in a structured format before your appointment. Include: symptom character (pressure, burning, sharp), location, radiation pattern, duration, triggers, relieving factors, frequency per week, and impact on daily activities. This documentation distinguishes cardiac-pattern symptoms from noncardiac mimics and supports the clinical case for advanced testing.

If you have already been told your heart is normal based on standard angiography alone, you have received an incomplete evaluation by 2020 diagnostic standards. You are not being difficult by requesting additional testing. You are requesting guideline-concordant care.

At your next cardiology appointment, bring this article and ask three questions by name: What was my Coronary Flow Reserve? What was my Index of Microvascular Resistance? Was acetylcholine provocation testing performed? If your cardiologist cannot answer these questions, the diagnostic evaluation is incomplete.

Frequently Asked Questions

What does ANOCA mean and how is it different from a normal heart?

ANOCA stands for Angina with Non-Obstructive Coronary Arteries. The definition requires angina symptoms plus coronary angiography showing less than 50% stenosis in major epicardial vessels. This is fundamentally different from a normal heart. ANOCA represents dysfunction in the coronary microcirculation or inappropriate vasospasm in epicardial arteries that appear structurally normal. The vessels look open but do not function properly. Blood flow cannot increase adequately during demand. The heart muscle becomes ischemic. The patient experiences real cardiac chest pain from real cardiac dysfunction. Standard angiography cannot visualize the microcirculation or capture transient vasospasm. When a cardiologist reports “clear arteries,” they are reporting only what angiography can see. ANOCA is what angiography cannot see.

Can ANOCA cause a heart attack?

Yes. Both ANOCA subtypes carry meaningful cardiovascular risk. Vasospastic angina can cause acute coronary syndrome through prolonged spasm that produces demand ischemia or through spasm-induced plaque rupture. The spasm itself can trigger thrombus formation at the site of maximal constriction. Microvascular angina causes cumulative ischemic injury that manifests as diastolic dysfunction, heart failure with preserved ejection fraction, and major adverse cardiovascular events. The WISE study demonstrated that women with severely impaired coronary flow reserve (CFR less than 2.0) had cardiovascular event rates equivalent to women with obstructive coronary artery disease. ANOCA patients in the Jespersen cohort had a 52% increased risk of cardiovascular death, MI, stroke, or heart failure hospitalization compared to angina-free controls. This is not a benign diagnosis.

What tests diagnose ANOCA definitively?

The gold standard is functional coronary angiography with invasive physiology testing. During cardiac catheterization, adenosine is infused to induce maximal hyperemia. Coronary Flow Reserve is calculated as the ratio of hyperemic to resting blood flow. A CFR less than 2.5 indicates microvascular dysfunction. Index of Microvascular Resistance is measured simultaneously using a pressure-temperature sensor wire. An IMR of 25 units or greater confirms elevated microvascular resistance. Acetylcholine provocation testing identifies vasospastic angina. Escalating doses of acetylcholine are injected into the coronary arteries. A positive test shows greater than 90% diameter reduction with reproduction of typical symptoms and ischemic ECG changes. Standard stress echocardiography and nuclear perfusion imaging miss approximately 60% of ANOCA cases because they are optimized for detecting obstructive epicardial disease, not diffuse microvascular dysfunction.

How is ANOCA treated?

Treatment depends entirely on subtype identification. Vasospastic angina requires calcium channel blockers as first-line therapy. Diltiazem 180 to 360 mg daily or amlodipine 5 to 10 mg daily reduces spasm frequency by 70 to 90%. Long-acting nitrates provide additional benefit. Beta-blockers are relatively contraindicated because they can worsen vasospasm. Microvascular angina requires the opposite approach. Beta-blockers reduce myocardial oxygen demand and are first-line. Ranolazine 500 mg twice daily improves diastolic function through late sodium current inhibition. ACE inhibitors enhance endothelial function. All ANOCA patients benefit from high-intensity statin therapy regardless of LDL level. The CorMicA trial demonstrated that mechanism-specific treatment following invasive physiology testing improved Seattle Angina Questionnaire scores by 70% compared to standard care.

Why do doctors say my heart is fine when I have ANOCA?

The explanation is historical and structural, not personal. Cardiology training for decades focused on obstructive coronary artery disease. The angiogram was the definitive test. Clear arteries meant a clear heart. The 2020 EAPCI Expert Consensus Document was the first major guideline to formally define ANOCA and establish diagnostic protocols. Cardiologists who completed training before 2020 received minimal education on coronary microvascular dysfunction. The equipment for invasive physiology testing requires specialized wires and protocols that many catheterization laboratories do not stock. Reimbursement incentives favor intervention over diagnostics. A cardiologist who performs a standard angiogram and finds no obstruction is following the training they received. That training was incomplete. The disease your doctor could not name is now recognized by international consensus. Requesting functional testing is not questioning your doctor’s competence. It is requesting care that aligns with current diagnostic standards.