Design and rationale of the NetherLands registry of invasive Coronary vasomotor Function Testing (NL-CFT)

Design and rationale of the efficacy of endothelin receptor antagonism in treatment of coronary artery spasm: a randomized controlled trial (EDIT-CAS)

BACKGROUND

Patients with angina and no obstructive coronary artery disease frequently have vasomotor dysfunction as the underlying mechanism for symptoms. Patients with vasomotor dysfunction have a high angina burden and their treatment frequently fails to reduce complaints sufficiently. Targeted therapies are currently unavailable due to heterogeneity in the patient population and incomplete understanding of the underlying pathophysiological mechanisms. One of the vasomotor dysfunction endotypes, epicardial spasm, is hypothesized to be a possible target for endothelin receptor antagonism treatment.

METHODS

The EDIT-CAS trial is a registry based, double blind, randomised, placebo-controlled clinical trial and aims to compare the efficacy of 10 weeks of add-on bosentan treatment versus placebo to prevent epicardial spasm at repeat spasm provocation test. Secondary and explorative outcomes are the effect on anginal complaints, safety of bosentan treatment, changes in coronary reactivity and the relationship between baseline endothelin levels and treatment success. We will include 100 patients with previously diagnosed epicardial vasospasm on a maximal triggering dose of 100 micrograms of acetylcholine and continuing angina(-like) symptoms at least weekly despite optimal medical treatment.

TRIAL REGISTRATION

The is registered in Clinical Trials Information System (2023-507782-25-00) and ClinicalTrials.gov (NCT06432452).

Challenges in diagnosing coronary microvascular dysfunction and coronary vasospasm

Chronic coronary syndromes (CCS) include 2 overlapping subgroups of patients - those with angina with nonobstructive coronary arteries (ANOCA), or ischaemia with non-obstructive coronary arteries (INOCA). A diagnosis of ANOCA-INOCA, is common and should be considered where angina is present and/or ischaemia is found on functional imaging in the absence of obstructive coronary artery disease (CAD) on coronary computed tomography angiography (CCTA) or invasive coronary angiography (ICA) (Ford and Berry, 2019). This review aims to provide an overview of contemporary challenges in the diagnosis of coronary microvascular dysfunction (CMD) and vasospastic disease, with a focus on recent guideline changes and current controversies. CMD and vasospastic angina (VSA) are increasingly acknowledged as an important and frequently overlooked, under investigated, and undertreated entities that contribute to ANOCA-INOCA (Samuels et al., 2023; Kunadian et al., 2020; Ford and Berry, 2019; Burgess and Mamas, 2024).

Safety, Feasibility, and Diagnostic Yield of Invasive Coronary Function Testing: Netherlands Registry of Invasive Coronary Vasomotor Function Testing

Importance

Patients with angina and no obstructive coronary artery disease frequently have coronary vasomotor dysfunction as underlying pathophysiological mechanism, comprising epicardial spasm, microvascular spasm, and/or microcirculatory dysfunction. These endotypes can be diagnosed by invasive coronary function testing which has previously shown to be safe in tertiary and expert centers.

Objective

To determine the prevalence of vasomotor dysfunction in patients with angina and no obstructive coronary artery disease who were clinically referred for a coronary function test (CFT); and assess safety and feasibility of a CFT.

Design, Setting, and Participants

This quality improvement study was performed using the Netherlands Registry of Invasive Coronary Vasomotor Function Testing (NL-CFT), a prospective, observational registry, in 15 participating hospitals (2 tertiary and 13 nontertiary). Patients with angina and no obstructive coronary artery disease who were referred for a clinically indicated CFT between December 2020 and January 2024 were included.

Main Outcomes and Measures

A complete CFT consisted of acetylcholine spasm provocation testing and assessment of microcirculatory function. Prevalence of different endotypes based on test results and overall safety were assessed.

Results

Among a total of 1207 patients included, 978 (81%) were female; and the mean (SD) age was 60 (10) years. The prevalence of coronary vasomotor dysfunction was very high (78%). There were 11 (0.9%) major and 10 (0.8%) minor complications reported. Of them, 3 major and all minor were definitely related to the coronary function test. No procedural death, myocardial infarction, or stroke was observed. No differences were found in the occurrence of complications between tertiary and nontertiary centers.

Conclusions and Relevance

This study found that a CFT was feasible and safe to perform in both tertiary and nontertiary centers with a high diagnostic yield.

Association Between Coronary Artery Spasm and Atherosclerotic Disease

In at least one-half of the patients with angina or ischemia and nonobstructive coronary arteries undergoing coronary function testing, coronary artery spasm (CAS) is detected. CAS is associated with an adverse prognosis regarding recurrent complaints and ischemic events. Current treatment options are mainly focused on the complaints, not on the underlying pathophysiological process. In this review we discuss available evidence regarding the presence, amount, and morphology of atherosclerosis in CAS patients. The reviewed evidence confirmed that atherosclerosis and vulnerable plaque characteristics are often detected in patients with CAS. The amount of atherosclerosis is higher in patients with focal CAS compared with patients with diffuse CAS. Severity of atherosclerosis is associated with the presence of CAS and the prognosis in CAS patients with atherosclerotic stenosis is worse. Therefore, CAS patients with atherosclerosis might benefit from targeted atherosclerotic treatment. Longitudinal studies are needed to elucidate the exact relation between atherosclerosis and CAS.

Angina Severity and Symptom Improvement Are Associated With Diagnostic Acetylcholine Provocation Dose in Vasospastic Angina

BACKGROUND

A coronary function test (CFT) is the recommended diagnostic test to identify coronary vasomotor dysfunction as a cause of symptoms in patients with angina and nonobstructive coronary arteries (ANOCA). Acetylcholine is the commonly used pharmacological agent for spasm provocation. We aimed to investigate an association between severity of symptoms and provocative acetylcholine dose.

METHODS AND RESULTS

We included ANOCA patients undergoing clinically indicated CFT from the Netherlands Registry of Invasive Coronary Vasomotor Function Testing: NL-CFT. Patients with epicardial spasm (n=251) were divided according to acetylcholine spasm triggering dose: low (2-20 mcg, EpiLOW), middle (100 mcg, EpiMIDDLE) or high (200 mcg, EpiHIGH). Patients with microvascular spasm (n=157) were analyzed irrespective of triggering dose. The patient groups were compared to each other and to a control group with negative CFT results (n=101). We assessed mean Seattle Angina Questionnaire angina frequency and summary scores at baseline and follow-up and the proportion of patients improving or deteriorating. An inverse relationship between provocation dosage and angina frequency at baseline was found in epicardial spasm: the lower the triggering dose, the more frequently patients experienced angina (EpiLOW 48±20, EpiMIDDLE 53±21, EpiHIGH 57±19, microvascular spasm 61±21, controls 64±21, overall P=0.003). A trend was seen toward most patients improving in the high triggering dose group, and most patients deteriorating in the low triggering dose group.

CONCLUSIONS

A significant dose-dependent relationship between spasm provocation and anginal complaints exists. Acetylcholine provocation dose could be incorporated as a risk stratification factor or surrogate outcome in future clinical trials.

REGISTRATION

URL: https://www.clinicaltrials.gov; Unique identifier: NCT06083155.

SoutheAsTern eUrope microciRculATION (SATURATION) registry - Design and rationale

BACKGROUND

A considerable number of symptomatic patients leave the cardiac catheterization lab without a definitive diagnosis for their symptoms because no epicardial stenoses are found. The significance of disorders of coronary microvasculature and vasomotion as the cause of symptoms and signs of ischemia has only recently been appreciated. Today we have a wide spectrum of invasive coronary physiology tools but little is known about when and how these tools are used in clinical practice.

STUDY DESIGN AND METHODOLOGY

SoutheAsTern eUrope microciRculATION (SATURATION) registry will study the regional practice of patient selection for coronary function testing, indications, non-invasive ischemia testing, medications, procedural aspects of invasive physiology evaluation, and treatment changes after testing. The registry is expected to include 1600 patients in participating centers in Southeastern Europe from 2024 to 2029, using the thermodilution technique for evaluation of microcirculation. Major adverse cardiovascular events as well as patient-centered outcomes such as burden of angina and quality of life using Seattle Angina Questionnaire (SAQ) and EQ-5D-5L will be recorded. The study will include patients with different stages of coronary artery disease (presence of disease or degree of stenosis) to elucidate the effect of coronary microcirculation on the outcomes in this broad group.

CONCLUSION

The registry will provide information regarding the current practice of invasive coronary physiology assessment in populations at high cardiovascular risk in Southeastern Europe. This could lead to a better understanding of coronary microvascular dysfunction and its relationship to various degrees of coronary atherosclerosis together with potential interventions that can be beneficial.

Effects of age on microvascular function in patients with normal coronary arteries

BACKGROUND

It has been suggested that coronary microvascular function decreases with age, irrespective of the presence of epicardial atherosclerosis.

AIMS

Our aim is to quantitatively investigate the effects of age on microvascular function in patients with normal coronary arteries.

METHODS

In 314 patients with angina with no obstructive coronary artery disease (ANOCA), microcirculatory function was tested using the continuous thermodilution method. In 305 patients, the association between age and both resting and hyperaemic myocardial blood flow (Q), microvascular resistance (Rμ), absolute coronary flow reserve (CFR) and microvascular resistance reserve (MRR) was assessed. In addition, patients were divided into 3 groups to test for differences based on age quartiles (≤52 years [24.9%], 53-64 years [49.2%], ≥65 years [25.9%]).

RESULTS

The mean age was 59±9 years with a range from 22 to 79 years. The mean resting Q (Qrest) was not different in the 3 age groups (88±34 mL/min, 82±29 mL/min, and 86±38 mL/min, R2=0.001; p=0.62). A trend towards a decreasing mean hyperaemic Q (Qmax) was observed with increasing age (223±79 mL/min, 209±84 mL/min, 200±80 mL/min, R2=0.010; p=0.083). The mean resting Rμ (Rμ,rest) were 1,204±460 Wood units (WU), 1,260±411 WU, and 1,289±455 WU (p=0.23). The mean hyperaemic Rμ (Rμ,hyp) increased significantly with advancing age (429±149 WU, 464±164 WU, 503±162 WU, R2=0.026; p=0.005). Consequently, MRR decreased with age (3.2±1.2, 3.1±1.0, 2.9±0.9; p=0.038). This trend was present in both the patients with (n=121) and without (n=184) coronary microvascular dysfunction (CMD).

CONCLUSIONS

There is an age-dependent physiological increase in minimal microvascular resistance and decrease in microvascular function, which is represented by a decreased MRR and is independent of atherosclerosis. The age-dependent decrease in MRR was present in both patients with and without CMD and was most evident in patients with smooth coronary arteries.

ANOCA patients with and without coronary vasomotor dysfunction present with limited electrocardiographic remodeling

Background

Coronary vasomotor dysfunction (CVDys) comprises coronary vasospasm (CVS) and/or coronary microvascular dysfunction (CMD) and is highly prevalent in patients with angina and non-obstructive coronary artery disease (ANOCA). Invasive coronary function testing (CFT) to diagnose CVDys is becoming more common, enabling pathophysiologic research of CVDys. This study aims to explore the electrophysiological characteristics of ANOCA patients with CVDys.

Methods

We collected pre-procedural 12-lead electrocardiograms of ANOCA patients with CVS (n = 35), CMD (n = 24), CVS/CMD (n = 26) and patients without CVDys (CFT-, n = 23) who participated in the NL-CFT registry and underwent CFT. Heart axis and conduction times were compared between patients with CVS, CMD or CVS/CMD and patients without CVDys.

Results

Heart axis, heart rate, PQ interval and QRS duration were comparable between the groups. A small prolongation of the QT-interval corrected with Bazett (QTcB) and Fridericia (QTcF) was observed in patients with CVDys compared to patients without CVDys (CVS vs CFT-: QTcB = 422 ± 18 vs 414 ± 18 ms (p = 0.14), QTcF = 410 ± 14 vs 406 ± 12 ms (p = 0.21); CMD vs CFT-: QTcB = 426 ± 17 vs 414 ± 18 ms (p = 0.03), QTcF = 413 ± 11 vs 406 ± 12 ms (p = 0.04); CVS/CMD vs CFT-: QTcB = 424 ± 17 vs 414 ± 18 ms (p = 0.05), QTcF = 414 ± 14 vs 406 ± 12 ms (p = 0.04)).

Conclusions

Pre-procedural 12-lead electrocardiograms were comparable between patients with and without CVDys undergoing CFT except for a slightly longer QTc interval in patients with CVDys compared to patients without CVDys, suggesting limited cardiac remodeling in patients with CVDys.

Continuous Versus Bolus Thermodilution-Derived Coronary Flow Reserve and Microvascular Resistance Reserve and Their Association With Angina and Quality of Life in Patients With Angina and Nonobstructive Coronaries: A Head-to-Head Comparison

Background Coronary flow reserve (CFR) and microvascular resistance reserve (MRR) are physiological parameters to assess coronary microvascular dysfunction. CFR and MRR can be assessed using bolus or continuous thermodilution, and the correlation between these methods has not been clarified. Furthermore, their association with angina and quality of life is unknown. Methods and Results In total, 246 consecutive patients with angina and nonobstructive coronary arteries from the multicenter Netherlands Registry of Invasive Coronary Vasomotor Function Testing (NL-CFT) were investigated. The 36-item Short Form Health Survey Quality of Life and Seattle Angina questionnaires were completed by 153 patients before the invasive measurements. CFR and MRR were measured consecutively with bolus and continuous thermodilution. Mean continuous thermodilution-derived coronary flow reserve (CFRabs) was significantly lower than mean bolus thermodilution-derived coronary flow reserve (CFRbolus) (2.6±1.0 versus 3.5±1.8; P<0.001), with a modest correlation (ρ=0.305; P<0.001). Mean continuous thermodilution-derived microvascular resistance reserve (MRRabs) was also significantly lower than mean bolus thermodilution-derived MRR (MRRbolus) (3.1±1.1 versus 4.2±2.5; P<0.001), with a weak correlation (ρ=0.280; P<0.001). CFRbolus and MRRbolus showed no correlation with any of the angina and quality of life domains, whereas CFRabs and MRRabs showed a significant correlation with physical limitation (P=0.005, P=0.009, respectively) and health (P=0.026, P=0.012). In a subanalysis in patients in whom spasm was excluded, the correlation further improved (MRRabs versus physical limitation: ρ=0.363; P=0.041, MRRabs versus physical health: ρ=0.482; P=0.004). No association with angina frequency and stability was found. Conclusions Absolute flow measurements using continuous thermodilution to calculate CFRabs and MRRabs weakly correlate with, and are lower than, the surrogates CFRbolus and MRRbolus. Absolute flow parameters showed a relationship with physical complaints. No relationship with angina frequency and stability was found.

Practical Approach for Angina and Non-Obstructive Coronary Arteries: A State-of-the-Art Review

Anginal symptoms are frequently encountered in patients without the presence of significant obstructive coronary artery disease (CAD). It is increasingly recognized that vasomotor disorders, such as an abnormal vasodilatory capacity of the coronary microcirculation or coronary vasospasm, are the dominant pathophysiological substrate in these patients. Although the evidence with respect to angina in patients with non-obstructive coronary arteries is accumulating, the diagnosis and treatment of these patients remains challenging. In this review, we aimed to provide a comprehensive overview regarding the pathophysiological origins of angina with non-obstructive coronary arteries disorders and its diagnostic and therapeutic considerations. Hereby, we provide a practical approach for the management of patents with angina and non-obstructive CAD.

Coronary Vascular (DYS) Function and Invasive Physiology Assessment: Insights into Bolus and Continuous Thermodilution Methods

A considerable number of patients with angina or myocardial ischemia have no significant coronary artery disease on invasive angiography. In recent years, several steps towards a better comprehension of the pathophysiology of these conditions, angina or ischemia with non-obstructive coronary arteries (ANOCA/INOCA), have been made. Nevertheless, several gaps in knowledge still remain. This review is intended to provide a comprehensive overview of ANOCA and INOCA, with a particular focus on pathophysiology, recent diagnostic innovations, gaps in knowledge and treatment modalities.