Coronary Artery Spasm Testing: Why Your Cath Report May Be Incomplete

Standard cardiac catheterization identifies blockages in 35% of women with angina. The remaining 65% are told their arteries are normal. Functional coronary assessment, including coronary flow reserve measurement and acetylcholine provocative testing, reveals treatable disease in up to 89% of these women according to the CorMicA trial. The distinction between anatomical and functional testing determines whether women receive diagnosis or dismissal.

Her cardiologist read the report: no significant obstructive coronary artery disease. Her symptoms were unchanged. She was told to go home. A complete functional assessment, ordered at a second opinion, found severe coronary vasospasm and a coronary flow reserve of 1.8. Her arteries were not just anatomy. They were biology.

I see this patient every week. She arrives with a folder of normal test results and a history of being told her symptoms are anxiety, acid reflux, or simply unexplained. She has undergone stress testing, sometimes a catheterization. The reports all say the same thing: no obstructive coronary artery disease. Her chest pain continues. Her quality of life deteriorates. Her confidence in her own body erodes.

The problem is not her symptoms. The problem is the incomplete diagnostic workup she received.

The Anatomy-Only Paradigm

Standard cardiac catheterization measures one thing: the diameter of the coronary artery lumen. A catheter delivers contrast dye. X-ray imaging captures the outline of the artery. A cardiologist estimates the percentage of narrowing. If the narrowing exceeds 50%, the stenosis is called significant. If it does not, the report reads “non-obstructive coronary arteries.”

This approach assumes that coronary artery disease is a plumbing problem. Find the blockage. Open the blockage. Problem solved.

For many patients, this model works. For women, it fails with remarkable consistency.

The WISE study (Women’s Ischemia Syndrome Evaluation, n=936) followed women referred for angiography due to suspected cardiac ischemia. The finding that reshaped our understanding: 62% had no significant epicardial stenosis. Their arteries looked open. Yet these women had symptoms, abnormal stress tests, and elevated cardiac risk. The anatomical assessment declared them disease-free. Their biology said otherwise.

The 2020 EAPCI Expert Consensus Document on Ischaemia with Non-Obstructive Coronary Arteries synthesized data from multiple registries and found the proportion even higher in contemporary practice, reaching 65% of women undergoing angiography for angina. 5 / Solid

Two out of three women leave the cath lab with a report that fails to explain their symptoms.

What the Standard Cath Does Not Measure

The coronary circulation is not a series of pipes. It is a living vascular network with three functional layers.

The epicardial arteries are the large vessels visible on angiography. They supply the surface of the heart. They are what the standard cath evaluates.

The microvascular bed consists of arterioles and capillaries less than 500 microns in diameter. These vessels are invisible to angiography. They regulate 70% of coronary vascular resistance. When they malfunction, blood flow to the heart muscle decreases despite open epicardial arteries.

The endothelium is the single-cell lining of every vessel. It produces nitric oxide, which controls vasodilation. When endothelial function fails, arteries that appear open cannot dilate appropriately under stress. They may even paradoxically constrict.

A standard catheterization evaluates the epicardial layer only. It cannot see the microvascular bed. It does not test endothelial function. It does not provoke vasospasm. It captures a snapshot of anatomy at rest and calls it complete.

This is like testing a car by photographing the engine and declaring it roadworthy without ever starting the ignition.

Functional Coronary Assessment: The Missing Tests

Functional coronary assessment adds three critical measurements to the anatomical picture.

Coronary Flow Reserve (CFR) measures the ratio of blood flow during hyperemia (maximal stress) to blood flow at rest. It is measured with a specialized pressure-temperature wire passed into the coronary artery. Adenosine or another vasodilator induces hyperemia. The wire records the response.

Normal CFR is above 2.5. A CFR below 2.0 is definitively abnormal. Murthy and colleagues at the University of Michigan followed patients with known or suspected coronary disease and found that those with CFR below 2.0 had a 3.2-fold increased risk of cardiac death, regardless of whether their angiogram showed blockages. The flow reserve predicted outcomes better than the anatomical findings. 5 / Solid

Index of Microcirculatory Resistance (IMR) isolates the microvascular component of coronary resistance. Using thermodilution during hyperemia, the wire calculates resistance in the vessels too small to see. An IMR of 25 units or higher indicates microvascular disease. The COVADIS position paper established this threshold as the diagnostic standard for microvascular dysfunction in the catheterization laboratory.

Provocative Testing for Vasospasm uses intracoronary acetylcholine to unmask coronary artery spasm. Acetylcholine is a neurotransmitter that causes normal arteries to dilate via nitric oxide release. In arteries with endothelial dysfunction, acetylcholine causes paradoxical vasoconstriction. In vasospastic arteries, it triggers focal or diffuse spasm.

The test is diagnostic when it reproduces the patient’s symptoms, documents transient coronary artery narrowing on angiography, or demonstrates ischemic ECG changes. The combination of these provocative and wire-based measurements transforms the catheterization from an anatomical photograph into a functional stress test.

The CorMicA Trial: Proof That Function Changes Outcomes

The CorMicA trial (Coronary Microvascular Angina) randomized 151 patients with angina and non-obstructive coronary arteries to either standard care or care guided by thorough functional coronary assessment. The functional protocol included CFR, IMR, and acetylcholine testing.

The results were unambiguous.

In the intervention arm, functional testing identified a specific diagnosis in 89% of patients who had previously been told their arteries were normal. Microvascular angina, vasospastic angina, or both were present in the overwhelming majority. Targeted treatment based on the functional diagnosis, rather than generic reassurance, improved angina symptoms by 11 points on the Seattle Angina Questionnaire at 6 months.

The control arm, which received standard care without functional assessment, showed no significant improvement.

This trial established a critical principle: the catheterization report that reads “no obstructive CAD” is not an endpoint. It is a decision node. The next question must be: was functional assessment performed?

If not, the workup is incomplete.

Women don’t die from what they have. Women die from what they hold. They hold incomplete reports and unanswered questions. They hold the burden of symptoms attributed to anxiety. They hold the accumulating cardiac risk that impaired flow reserve predicts.

The Three Functional Diagnoses Your Report May Be Missing

When functional coronary assessment is performed, three diagnoses emerge with regularity.

Microvascular Angina is defined by impaired CFR (below 2.0) or elevated IMR (above 25) in the absence of epicardial stenosis. The microvasculature fails to dilate appropriately. Blood flow during stress is inadequate. Symptoms occur with exertion, sometimes at rest. The 2019 ESC Guidelines for chronic coronary syndromes formally recognize microvascular angina as a distinct clinical entity requiring specific management.

Vasospastic Angina is defined by acetylcholine-induced coronary artery spasm, either focal (greater than 90% constriction) or diffuse (greater than 50% constriction across multiple segments). Symptoms classically occur at rest, often in the early morning hours. Episodes may be triggered by cold, emotional stress, or hyperventilation. The acetylcholine provocation test is diagnostic.

Mixed Microvascular and Vasospastic Disease combines both pathophysiologies. The CorMicA trial found that a significant proportion of patients had abnormalities in both domains. This overlap explains why single-mechanism treatment often fails and why thorough testing is essential.

The WISE study follow-up data published by Taqueti and colleagues demonstrated that women with non-obstructive disease and impaired coronary microvascular function had elevated risk of developing heart failure with preserved ejection fraction. The microvascular dysfunction was not benign. It predicted future myocardial disease. 5 / Solid

Why Most Cath Labs Do Not Perform Functional Assessment

If functional testing changes diagnosis and management in nearly 90% of women with non-obstructive arteries, why is it not standard practice?

The reasons are structural, not scientific.

Equipment requirements. Coronary flow reserve and IMR measurement require specialized pressure-temperature wires. Not all cath labs stock them. Not all operators are trained in their use.

Time constraints. A standard diagnostic catheterization takes 20 to 30 minutes. Adding functional assessment extends this to 45 to 60 minutes. In high-volume labs, time is the limiting resource.

Reimbursement models. The current procedural coding structure does not adequately compensate for the additional time and expertise required for functional assessment. The economic incentives favor volume over completeness.

Training gaps. Interventional cardiology fellowship programs have historically emphasized epicardial revascularization. Functional assessment of non-obstructive disease receives less attention. Many practicing interventional cardiologists did not learn these techniques during their training.

Diagnostic inertia. For decades, “no obstructive CAD” was considered a reassuring result. It takes time for practice patterns to incorporate new evidence. The CorMicA trial was published in 2018. The EAPCI consensus document appeared in 2020. Guideline implementation always lags behind guideline publication.

The result is a two-tiered system. Centers with dedicated programs in coronary physiology and women’s cardiovascular health offer complete functional assessment. The majority of community cath labs do not.

The Language to Request Complete Assessment

You cannot demand what you cannot name. Here is the language to use.

Before your catheterization, ask your cardiologist: “If my angiogram shows non-obstructive coronary arteries, will you perform functional coronary assessment including coronary flow reserve and provocative testing for vasospasm?”

If the answer is no, ask: “Can you refer me to a center that performs thorough invasive coronary physiology testing?”

If you have already had a catheterization that showed “normal arteries” and your symptoms persist, say: “I understand my angiogram did not show significant blockages. However, I have continued symptoms and am concerned about microvascular disease or coronary vasospasm. I would like to be evaluated at a center that performs complete functional coronary assessment including CFR, IMR, and acetylcholine testing.”

Name the tests. Name the diagnoses you are concerned about. Name your symptoms and their impact on your life.

The clinical framework I use is called The Functional Completeness Standard. An invasive coronary evaluation is complete only when it addresses three questions: Is there epicardial obstruction? Is coronary flow reserve preserved? Is there provokable vasospasm? If any question remains unanswered, the workup is incomplete.

Centers Performing Complete Functional Assessment

Several academic medical centers have established programs in coronary microvascular disease and vasospastic angina. These centers perform the full complement of functional testing and have published their protocols and outcomes.

Cedars-Sinai Smidt Heart Institute (Los Angeles) houses the Barbra Streisand Women’s Heart Center, which has been central to WISE study research. They perform routine CFR, IMR, and acetylcholine testing in women with non-obstructive coronary disease.

Mayo Clinic (Rochester) has a dedicated coronary physiology laboratory and has published extensively on microvascular angina diagnosis and management.

Cleveland Clinic offers thorough invasive coronary function testing through its Women’s Cardiovascular Center.

Brigham and Women’s Hospital (Boston) has an active research program in coronary microvascular disease and performs functional assessment in the cath lab.

University of Florida Health has developed protocols for acetylcholine provocation testing and manages a substantial population of patients with vasospastic angina.

When calling these centers, ask specifically: “Do you perform invasive coronary physiology testing including CFR, IMR, and acetylcholine provocation for patients with non-obstructive coronary disease?” The answer should be yes without hesitation.

What Changes When You Get the Right Diagnosis

Diagnosis changes treatment. Treatment changes outcomes.

For microvascular angina, first-line therapy includes beta-blockers or calcium channel blockers to reduce myocardial oxygen demand. Ranolazine, which improves myocardial relaxation without affecting heart rate or blood pressure, has evidence in this population. ACE inhibitors improve endothelial function. Statins reduce vascular inflammation. Exercise training improves microvascular function over time.

For vasospastic angina, calcium channel blockers are the cornerstone of treatment. Long-acting nitrates may be added. Beta-blockers, paradoxically, can worsen vasospasm in some patients and are used cautiously if at all. Trigger avoidance, including smoking cessation and cold exposure management, is essential.

For mixed disease, combination therapy addressing both pathophysiologies is required.

The CorMicA trial demonstrated that targeted treatment based on functional diagnosis produces measurable symptom improvement. Generic reassurance does not.

The Report You Deserve

Your catheterization report should answer these questions:

1. Is there obstructive epicardial coronary artery disease? (Anatomical assessment)
2. What is the coronary flow reserve? (Functional assessment)
3. What is the index of microcirculatory resistance? (Microvascular assessment)
4. Was provocative testing for vasospasm performed? If so, what was the result? (Vasospasm assessment)

If your report addresses only the first question, you have received an incomplete evaluation. This is not a criticism of your cardiologist. It is a statement about the current state of practice. The standard of care is evolving. Your advocacy can accelerate that evolution.

At your next cardiology appointment, bring this article. Ask for the four-question assessment. If your center cannot provide it, request referral to one that can.

Your symptoms are real. Your coronary physiology is measurable. The tests exist. The treatments work. The only barrier is asking the right questions and refusing to accept an incomplete answer.

Frequently Asked Questions

Why did my cardiologist say my heart is fine when I still have chest pain?

Standard cardiac catheterization evaluates coronary artery diameter using contrast dye and X-ray imaging. It identifies blockages of 50% or greater. It does not measure blood flow, microvascular resistance, or the tendency of arteries to spasm. If your large arteries are open but your small vessels are dysfunctional, or if your arteries constrict paradoxically under stress, the standard catheterization will not detect it. The test measures anatomy, not physiology. Your symptoms may be caused by coronary microvascular disease or vasospastic angina, both of which require functional testing, not anatomical imaging, for diagnosis. Request coronary flow reserve measurement and acetylcholine provocative testing.

What tests should I ask for if my cath was normal but I still have symptoms?

Request three specific tests: coronary flow reserve (CFR) measurement using a pressure-temperature wire during adenosine infusion, index of microcirculatory resistance (IMR) to evaluate your small vessel function, and acetylcholine provocative testing to unmask coronary vasospasm. These tests require specialized equipment and operator expertise. Not all cath labs perform them routinely. Ask your cardiologist directly: “Do you perform thorough functional coronary assessment including CFR, IMR, and acetylcholine provocation?” If the answer is no, request referral to an academic center with a dedicated coronary physiology program.

How common is it to have chest pain with normal-looking arteries?

Extremely common, particularly in women. The WISE study found that 62% of women referred for cardiac catheterization due to suspected ischemia had no significant epicardial stenosis. Contemporary data suggests this proportion may be as high as 65% in women. These women were not symptom-free. They had angina, abnormal stress tests, and elevated cardiovascular risk. Subsequent functional testing in this population reveals abnormal coronary flow reserve, elevated microvascular resistance, or provokable vasospasm in the majority. The normal angiogram does not mean normal coronary function. It means the anatomical portion of the evaluation was negative.

What is coronary flow reserve and why does it matter?

Coronary flow reserve is the ratio of coronary blood flow during maximal stress (hyperemia) to blood flow at rest. It measures the reserve capacity of your coronary circulation, the ability to increase blood supply when your heart demands more oxygen. Normal CFR exceeds 2.5. A CFR below 2.0 is definitively abnormal. Research from the University of Michigan demonstrated that patients with CFR below 2.0 have a 3.2-fold increased risk of cardiac death, regardless of whether their angiogram shows blockages. The flow reserve predicts outcomes better than the anatomical appearance of the arteries. This is why functional testing matters: it identifies risk that anatomical imaging misses.

Where can I get complete functional coronary testing?

Academic medical centers with dedicated women’s heart programs or coronary physiology laboratories are most likely to offer thorough functional assessment. Cedars-Sinai Smidt Heart Institute in Los Angeles, Mayo Clinic in Rochester, Cleveland Clinic, and Brigham and Women’s Hospital in Boston have established protocols for CFR, IMR, and acetylcholine testing. When contacting these centers, ask specifically whether they perform invasive coronary physiology testing for patients with non-obstructive coronary disease. Confirm that acetylcholine provocation testing is available. Travel may be required, but accurate diagnosis is worth the investment.