# Ischaemia with Non-Obstructive Coronary Arteries

> Ischaemia with non-obstructive coronary arteries for NEET-PG Medicine: microvascular dysfunction, vasospasm, MINOCA causes, provocation testing and cardiac MRI.

- Canonical URL: https://prepelephant.com/topics/neet-pg/medicine/ischaemia-with-non-obstructive-coronary-arteries
- Exam / course: NEET-PG · Subject: Medicine
- Publisher: PrepElephant (https://prepelephant.com) — Prepared and reviewed by the PrepElephant Academic Review Team
- First published: 2026-10-14
- Last updated: 2026-10-14
- Reference basis: Braunwald's Heart Disease; Harrison's Principles of Internal Medicine; ESC Guidelines on chronic coronary syndromes
- How to cite: "Ischaemia with Non-Obstructive Coronary Arteries", PrepElephant, https://prepelephant.com/topics/neet-pg/medicine/ischaemia-with-non-obstructive-coronary-arteries

## Direct answer

Ischaemia with non-obstructive coronary arteries is myocardial ischaemia, or infarction, in a patient whose angiogram shows no stenosis large enough to explain it. The cause lies in the coronary microcirculation, in epicardial vasospasm, in plaque erosion, in embolism or in a non-atherosclerotic process such as dissection. Invasive measurement of coronary flow reserve and acetylcholine provocation testing separate these mechanisms and guide treatment.

## What you must remember

- **Definitions:** ANOCA describes angina with non-obstructive arteries, and MINOCA describes myocardial infarction with no coronary stenosis of 50 percent or more.
- **Who:** women, especially after the menopause, and patients with hypertension, diabetes or dyslipidaemia are over-represented.
- **Microvascular dysfunction:** impaired dilatation of small arterioles, with low coronary flow reserve and often endothelial dysfunction.
- **Vasospasm:** transient epicardial narrowing, confirmed by acetylcholine provocation during angiography with at least 90 percent narrowing and reproduction of symptoms.
- **Other MINOCA causes:** plaque erosion or rupture with resolved thrombus, coronary embolism, spontaneous coronary artery dissection, myocarditis and Takotsubo syndrome.
- **Cardiac MRI:** mid-wall or subepicardial late gadolinium enhancement outside a coronary territory suggests myocarditis, whereas subendocardial enhancement in one territory suggests infarction.
- **Treatment:** calcium channel blockers and nitrates are first-line for spasm, while microvascular angina is treated with beta-blockers or calcium channel blockers, with statins and ACE inhibitors for vascular risk.
- **Beta-blockers:** non-selective agents can worsen spasm and are avoided in vasospastic disease.

## A pathway for the clean-artery patient

A 52-year-old woman has exertional chest tightness and a positive exercise test, but her coronary angiogram shows smooth arteries with no lesion above 30 percent. The evaluation now asks which mechanism explains her symptoms.

1. **Exclude acute coronary syndrome.** Serial troponin and an ECG establish whether infarction has occurred before the case is classed as stable.
2. **Review the angiogram critically.** Intravascular ultrasound or optical coherence tomography can reveal a plaque or dissection that angiography missed.
3. **Test for vasospasm.** Escalating intracoronary acetylcholine during angiography reproduces spasm, which is confirmed by at least 90 percent narrowing with symptoms and ECG change.
4. **Measure microvascular function.** Coronary flow reserve below about 2.0 or a raised index of microvascular resistance suggests coronary microvascular dysfunction.
5. **Check the myocardium.** Cardiac MRI looks for the oedema and late gadolinium enhancement pattern of myocarditis, Takotsubo syndrome or a small infarct.
6. **Match the drug to the mechanism.** Calcium channel blockers and nitrates target spasm, beta-blockers or calcium channel blockers suit microvascular angina, with risk factor control added for atherosclerotic disease.

## Where the exam tries to catch you

Clean-artery questions reward the candidate who keeps investigating after a normal angiogram.

- **Trap:** calling a normal-looking angiogram reassuring and stopping the workup — **Correct:** angiography excludes only obstructive stenosis, so infarction with clean arteries still needs assessment for erosion, embolism, dissection and myocarditis.
- **Trap:** using beta-blockers as default anti-anginal therapy in vasospastic angina — **Correct:** calcium channel blockers and nitrates are preferred, because non-selective beta-blockers can worsen spasm.
- **Trap:** dismissing chest pain with clean arteries as anxiety — **Correct:** microvascular and vasospastic angina are objective ischaemic conditions with real prognostic weight, and they need treatment.

## Frequently asked questions

### What is the difference between ANOCA and MINOCA?

ANOCA stands for angina with non-obstructive coronary arteries and describes ischaemic symptoms without infarction. MINOCA stands for myocardial infarction with non-obstructive coronary arteries, where troponin rises but the angiogram shows no significant stenosis.

### Which test confirms coronary vasospasm?

Intracoronary provocation testing with acetylcholine, performed during coronary angiography, confirms vasospasm. Spasm is diagnosed when the artery narrows by at least 90 percent with reproduction of the patient's symptoms and ECG change.

### Which cardiac MRI pattern suggests myocarditis rather than infarction?

A mid-wall or subepicardial late gadolinium enhancement that does not follow a coronary territory suggests myocarditis. Infarction typically shows subendocardial enhancement confined to one coronary distribution.

### What is coronary flow reserve and why is it measured?

Coronary flow reserve is the ratio of maximal to resting coronary blood flow, measured with an intracoronary Doppler or thermodilution wire. A value below about 2.0 suggests coronary microvascular dysfunction in patients whose arteries are non-obstructive.