Differences in diagnostic yield of invasive coronary function testing between high and low volume centres, in patients with angina and no obstructive coronary artery disease
Authors: Crooijmans C , Jansen T P J , Meeder J , Konst R E , Paradies V , De Vos A , Appelman Y , Winkler P , Den Ruijter H , Onland-Moret C , Van De Hoef T P , Dimitriu-Leen A L , Elias-Smale S E , Van Royen N , Damman P 
Published: November 2023

Abstract

Introduction
Coronary angiograms for stable angina frequently show no obstructive coronary artery disease (ANOCA). A large proportion of ANOCA patients have underlying coronary vasomotor dysfunction. They can be divided into different endotype subgroups, according to their invasive coronary function test (CFT) results. A complete CFT in the studied cohort consists of both spasm provocation with acetylcholine as well as testing physiology of the microcirculation with adenosine and bolus thermodilution. There is a high prevalence of vasomotor dysfunction in our tertiary, high volume CFT centre where &gt;100 CFT s are performed each year. No data is available yet on the prevalence in low volume centres.

Purpose
To compare CFT results of patients who underwent complete CFT in a high volume centre versus low volume centres.

Methods
We included all consecutive patients from the pilot version of a prospective national registry of coronary function tests in the Netherlands (NL-CFT) who underwent a complete standardized CFT between February 2019 and January 2023 (n=593). We compared CFT diagnosis (endotypes) in high versus low volume centres by acetylcholine spasm provocation and adenosine bolus thermodilution test results. A high volume CFT centre was defined as performing more than 100 CFT’s per year. Coronary microvascular dysfunction (CMD) was defined as a coronary flow reserve CFR &lt;2 and/or index of microvascular resistance IMR ≥25. Coronary vasomotor dysfunction was present when epicardial or microvascular spasm was diagnosed, when CFR and/or IMR was abnormal, or when both parts of the CFT were abnormal. We expect to be able to present expanded data on approximately 1000 patients with complete CFTs around the ESC congress.

Results
Currently, 593 patients underwent complete CFT (83% female, mean age 60 ± 9.5 years). The high volume centre performed 307 (52%) of all CFTs in the studied period. The four low volume centres combined performed the other 286 (48%). A total of 461 (78%) of patients had coronary vasomotor dysfunction.
Prevalence of coronary vasomotor dysfunction was significantly higher in a high volume centre compared to low volume centres (88% vs 66% p&lt;0.001). Coronary spasm was present in 84% of CFTs in a high volume centre: 54% isolated and 30% combined with CMD. Isolated CMD was present in 4% and only 12% had a normal CFT.
In low volume centres coronary spasm was present in 54% of patients: 36% isolated and 19% combined with CMD. Isolated CMD was present in 12% and 34% of all performed CFT’s was normal.

Conclusions
In this pilot data of NL-CFT, a large prospective registry, 593 patients underwent complete CFT. We show that the prevalence of coronary vasomotor dysfunction is significantly higher in a high volume CFT centre compared to low volume centres. Vasospasm is the predominant endotype, either isolated or combined with CMD. Nevertheless, prevalence of vasomotor dysfunction in low volume centres is still high and warrants attention.Distribution of endotypes