Intracoronary Acetylcholine Provocation Testing for Assessment of Coronary Vasomotor Disorders
August 18th, 2016
Intracoronary acetylcholine testing has been established for the assessment of epicardial coronary spasm more than 30 years ago. Recently, the focus has shifted towards the microcirculation and it has been shown that microvascular spasm can be detected using ACH-testing. This article describes the ACH-test and its implementation in daily routine.
The overall goal of the Acetylcholine Test is to assess whether a patient suffers from a coronary vasomotor disorder such as an epicardial or coronary microvascular spasm. The acetylcholine test is helpful for detecting a coronary vasomotor disorder. Especially in patients with angina pectoris and unobstructed coronary arteries.
The wonderful thing about the acetylcholine test is that you can perform it immediately after diagnostic angiography. And it doesn't cost a lot of money and it doesn't take a lot of time. Before beginning the procedure, mix 20 milligrams of acetylcholine with two milliliters of the acetylcholine solvent.
Then mix two milliliters of the resulting acetylcholine solution with 98 milliliters of 0.9%sodium chloride. Next add nine milliliters of this 0.2 milligram per milliliter acetylcholine solution with 91 milliliters of sodium chloride to achieve an 18 microgram per milliliter aceteylcholine solution and label the container High"Fill a 50 milliliter profusion syringe with 40 milliliters of the 18 microgram per milliliter acetylcholine solution. Then transfer eight milliliters of the acetylcholine solution from the High"syringe into a second 50 milliliter profusion syringe and add 32 milliliters of sodium chloride into the second syringe to achieve a 3.6 microgram per milliliter acetylcholine dose.
Label this syringe Medium"Transfer four milliliters of the medium concentration of acetylcholine into a third 50 milliliter profusion syringe. Add 36 milliliters of sodium chloride to the third syringe to obtain a 0.36 microgram per milliliter acetylcholine dose. And label this syringe Low"After injecting local anesthesia in proximity to the patient's right radial artery, confirm that the region is numb.
Then place a catheter according to standard protocols. After visually excluding any epicardial stenosis, inject six liters of the two microgram Low"acetylcholine dose into the left coronary artery over the course of 20 seconds while monitoring ECG and the patient's symptoms. Then inject 10 milliliters of contrast agent manually via a contrast syringe into the catheter to visualize the coronary arteries.
After one minute inject six milliliters of the 20 microgram Medium"acetylcholine dose into the left coronary artery as performed for the low dose. Follow this by injecting 10 milliliters of contrast agent. After another minute, repeat the injection with 5.5 milliliters of the 100 microgram High"acetylcholine dose.
Again follow the acetylcholine injection with 10 milliliters of contrast agent. Most patients will develop symptoms, ECG changes, or an epicardial spasm at this dose. If bradycardia is observed on the ECG, reduce the speed of the injection and observe the ECG carefully.
If no spasm has occurred after one minute, administer 11 milliliters of the 200 microgram High"acetylcholine dose. Followed by 10 milliliters of contrast agent. If no abnormal findings are observed, inject 4.5 milliliters of the 80 microgram acetylcholine dose into the right coronary artery as just demonstrated followed by 10 milliliters of contrast agent.
Then inject 200 microgram of intracoronary nitroglycerin into each tested artery and image the vessel after one minute as just demonstrated to document the reversion of the spasm. Epicardial coronary spasm is diagnosed when an epicardial vasoconstriction greater than or equal to 90%compared to the relaxed state after nitroglycerin administration together with ischemic ECG shifts and a reproduction of the patient's symptoms are observed. A microvascular spasm is diagnosed in the case of a reproduction of the patient's symptoms with ischemic ECG shifts, usually ST segment depression during the acetylcholine test without any epicardial vasoconstriction greater than or equal to 90%Remember that the interpretation of the acetylcholine test is based on patient's symptoms, ECG shifts, and the angiographic appearance of the coronary arteries during the test.
I hope this video will encourage interventional cardiologists to incorporate the acetylcholine test into their diagnostic armamentarium because the result of this test informs about the patient's symptoms, the cause of the patient's symptoms and it helps to select the appropriate treatment.
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Overview
The Acetylcholine Test is a diagnostic procedure used to assess coronary vasomotor disorders, including epicardial and microvascular spasms. This test is particularly beneficial for patients experiencing angina pectoris with unobstructed coronary arteries, allowing for immediate assessment following diagnostic angiography.
Key Study Components
Area of Science
- Cardiology
- Vascular Medicine
- Diagnostic Testing
Background
- Intracoronary acetylcholine testing has been used for over 30 years.
- Recent research has focused on detecting microvascular spasms.
- The acetylcholine test is cost-effective and time-efficient.
- It can be performed immediately after diagnostic angiography.
Purpose of Study
- To evaluate the presence of coronary vasomotor disorders.
- To identify microvascular spasm in patients with angina.
- To improve diagnostic accuracy in patients with unobstructed coronary arteries.
Methods Used
- Mixing 20 milligrams of acetylcholine with two milliliters of solvent.
- Administering the acetylcholine solution during coronary angiography.
- Monitoring patient responses to assess for spasms.
- Utilizing diagnostic imaging techniques for evaluation.
Main Results
- The acetylcholine test successfully identifies coronary vasomotor disorders.
- Microvascular spasms can be detected effectively.
- Patients with angina and unobstructed arteries show significant responses.
- The procedure is quick and cost-effective.
Conclusions
- The acetylcholine test is a valuable tool in diagnosing coronary disorders.
- It enhances understanding of microvascular function.
- Further research may expand its applications in clinical practice.
Frequently Asked Questions
Executive Industry Relevance
Intracoronary acetylcholine provocation testing enables precise functional assessment of coronary vasomotor disorders in patients with angina and unobstructed arteries. This diagnostic capability supports mechanistic de-risking and target validation at the interface of cardiovascular discovery and translational research. Reliable identification of epicardial and microvascular spasm informs portfolio decisions and enhances predictive confidence in early-stage cardiovascular programs.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Enables interrogation of coronary vasomotor function to clarify disease mechanisms.
- Supports biological de-risking by distinguishing epicardial from microvascular spasm.
- Provides functional target validation for vascular tone modulation strategies.
- Facilitates predictive confidence in mechanistic hypotheses for angina without obstructive disease.
Screening & Assay Development
- Establishes a validated in vivo system for functional vascular response assessment.
- Delivers reproducible, quantitative outputs via ECG shifts and angiographic readouts.
- Supports standardization of vasomotor challenge protocols for compound evaluation.
- Enables screening of pharmacological agents targeting coronary vasomotion.
Translational & Preclinical Research
- Aligns with disease-relevant endpoints for translational biomarker development.
- Bridges discovery findings to preclinical validation in human-relevant systems.
- Informs risk-adjusted advancement of vascular-targeted therapeutics.
- Provides mechanistic de-risking for late-stage cardiovascular assets.
Pipeline & Workflow Integration
The acetylcholine provocation test integrates into the discovery-to-preclinical continuum as a functional diagnostic for coronary vasomotor disorders.
- Discovery Biology: Supports hypothesis testing on vascular reactivity and spasm mechanisms.
- Screening: Offers reproducible, quantitative assessment of coronary response to pharmacological challenge.
- Analytics: Provides ECG and angiographic measurements for comparative analysis across conditions.
- Translational Research: Connects mechanistic findings to clinical symptomatology and biomarker alignment.
- Enterprise Reuse: Functions as a reusable diagnostic platform for cardiovascular R&D portfolios.
Operational & Enterprise Impact
- Scientific Value: Increases predictive confidence and reduces mechanistic ambiguity in coronary disease models.
- Operational Value: Delivers standardized, rapid, and cost-effective functional testing.
- Strategic Value: Enables informed go/no-go decisions and reduces late-stage biological risk in cardiovascular programs.
- Portfolio Impact: Supports risk-adjusted prioritization and advancement of vascular-targeted assets.
Implementation Considerations
- Requires expertise in interventional cardiology and coronary physiology.
- Needs access to catheterization laboratory and ECG/angiographic infrastructure.
- Demands cross-team standardization of dosing and readout protocols.
- Adaptation may be needed for different patient populations or model systems.
- Interpretation depends on integration of symptoms, ECG, and angiographic data.
