Intracoronary Acetylcholine Provocation Testing for Assessment of Coronary Vasomotor Disorders

Summary

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.

Abstract

Intracoronary acetylcholine provocation testing (ACH-test) is an established method for assessment of epicardial coronary artery spasm in the catheterization laboratory which was introduced more than 30 years ago. Due to the short half-life of acetylcholine it can only be applied directly into the coronary arteries. Several studies have demonstrated the safety and clinical usefulness of this test. However, acetylcholine testing is only rarely applied in the U.S. or Europe. Nevertheless, it has been shown that 62% of Caucasian patients with stable angina and unobstructed coronary arteries on coronary angiography suffer from coronary vasomotor disorders that can be diagnosed with acetylcholine testing. In recent years it has been appreciated that the ACH-test not only assesses the presence of epicardial spasm but that it can also be useful for the detection of coronary microvascular spam. In such cases no epicardial spasm is seen after injection of acetylcholine but ischemic ECG shifts are present together with a reproduction of the patient's symptoms during the test. This article describes the experience with the ACH-test and its implementation in daily clinical routine.

Introduction

Angina pectoris is the hallmark of coronary artery disease and the concept of an epicardial stenosis causing myocardial ischemia and exercise-induced angina has been established for many years. However, many patients with angina pectoris do not have the typical triad of retrosternal pain, onset during exercise and relief by nitroglycerine or rest. Frequently patients report angina pectoris at rest or a combination of exertional and resting angina as well as shortness of breath upon exertion as a possible angina equivalent. In 1959 Prinzmetal was the first to introduce the concept of transient spasm of the coronary arteries causing angina at rest associated with ST-seg....

Protocol

NOTE: Intracoronary acetylcholine testing has been approved by the local ethics committee and the protocol follows the guidelines of our institution for human research.

1. Preparation of the Acetylcholine Solutions (See Materials Table)

1. Mix the 20 mg acetylcholine with the 2 ml solvent provided with the package.
2. Add the 2 ml ACH solution to 98 ml of NaCl 0.9 %. This corresponds to a dose of 0.2 mg/ml and is called stock solution 1. Add 9 ml of stock solution 1 to 91 ml of NaCl 0.9%, This corresponds to a dose of 18 µg/ml and is called stock solution 2.
3. Prepare 3 perfusion syringes (each of 50 ml) labeled....

Results

Interpretation of the acetylcholine test is based on three criteria. First, the patient is asked throughout the test whether or not symptoms occur. Frequently, patients report a reproduction of their usual symptoms such as chest pain, shortness of breath or other symptoms. This represents an important point for the overall interpretation of the test. Second, a 12-lead-ECG registration is continuously performed throughout the test with a special emphasis on ischemic ECG shifts such as ST-s.......

Discussion

It is feasible to implement the acetylcholine test in daily clinical routine in the catheterisation laboratory. Apart from the preparation of the ACH solutions there are several technical issues that have to be resolved before starting the test including radiolucent ECG leads for continuous 12-lead ECG registration. This is essential to be able to detect transient ischemic ECG changes during the test. Moreover, it is important to know that the ACH solutions can only be used for 2 hr. After that they should be newly prepa.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Vial of 20 mg acetylcholine chloride powder and 1 Ampoule of 2 ml diluent	Bausch & Lomb	NDC 24 208-539-20
3x 100 ml NaCl 0.9 %	BBraun	3200950
3x syringe 50 ml each	BBraun	4187903
1x 2 ml syringe	BBraun	4606027V
1x 10 ml syringe	BBraun	4606108V
2x cannula 20 G 70 mm	BBraun	4665791
5x 5 ml syringe	BBraun	4606051V
Contrast agent Imeron 350 with a 10 ml syringe for contrast injection	Bracco Imaging	30699.03.00
Coronary angiography suite (AXIOM Artis MP eco )	Siemens	n/a