Dose-Response Relationship Between Intracoronary Acetylcholine and Minimal Lumen Diameter in Coronary Endothelial Function Testing of Women and Men With Angina and No Obstructive Coronary Artery Disease

Muscarinic control of cardiovascular function in humans: a review of current clinical evidence

PURPOSE

To review the available evidence on the impact of muscarinic receptor modulation on cardiovascular control in humans.

METHODS

In this narrative Review we summarize data on cardiovascular endpoints from clinical trials of novel subtype-selective or quasi-selective muscarinic modulators, mostly PAMs, performed in the last decade. We also review the cardiovascular phenotype in recently described human genetic and autoimmune disorders affecting muscarinic receptors.

RESULTS

Recent advancements in the development of compounds that selectively target muscarinic acetylcholine receptors are expanding our knowledge about the physiological function of each muscarinic receptor subtype (M1, M2, M3, M4, M5). Among these novel compounds, positive allosteric modulators (PAMs) have emerged as the preferred therapeutic to regulate muscarinic receptor subtype function. Many muscarinic allosteric and orthosteric modulators (including but not limited to xanomeline-trospium and emraclidine) are now in clinical development and approaching regulatory approval for multiple indications, including the treatment of cognitive and psychiatric symptoms in patients with schizophrenia as well as Alzheimer's disease and other dementias. The results of these clinical trials provide an opportunity to understand the influence of muscarinic modulation on cardiovascular autonomic control in humans. While the results and the impact of each of these therapies on heart rate and blood pressure control have been variable, in part because the clinical trials were not specifically designed to measure cardiovascular endpoints, the emerging data is valuable to elucidate the relative cardiovascular contributions of each muscarinic receptor subtype.

CONCLUSION

Understanding the muscarinic control of cardiovascular function is of paramount importance and may contribute to the development of novel therapeutic strategies for treating cardiovascular disease.

Insights into the invasive diagnostic challenges of coronary artery vasospasm - A systematic review

Coronary provocation testing is an essential diagnostic procedure when evaluating vasospastic angina. Invasive methods using acetylcholine or ergonovine are considered the current gold standard. Despite efforts from global cardiovascular institutions, current protocols vary in dosage, administration time, and procedural approach. In addition, concerns over the specificity of findings and potential complications have limited routine uptake of this procedure in clinical practice. This systematic review evaluates current diagnostic protocols, focusing on invasive provocation testing. We included studies using intracoronary provocation testing with acetylcholine or ergonovine for the assessment of coronary artery vasospasm that detailed specific elements of the procedure (dosage, administration time, etc.) and included ≥50 patients. A total of 28 articles met strict inclusion criteria. Our review highlights the heterogeneity between current diagnostic protocols for invasive provocation testing. We believe standardization of a diagnostic protocol will encourage both current and future cardiologists to incorporate such procedures in the evaluation of variant angina.

Comprehensive Management of ANOCA, Part 1-Definition, Patient Population, and Diagnosis: JACC State-of-the-Art Review

Angina with nonobstructive coronary arteries (ANOCA) is increasingly recognized and may affect nearly one-half of patients undergoing invasive coronary angiography for suspected ischemic heart disease. This working diagnosis encompasses coronary microvascular dysfunction, microvascular and epicardial spasm, myocardial bridging, and other occult coronary abnormalities. Patients with ANOCA often face a high burden of symptoms and may experience repeated presentations to multiple medical providers before receiving a diagnosis. Given the challenges of establishing a diagnosis, patients with ANOCA frequently experience invalidation and recidivism, possibly leading to anxiety and depression. Advances in scientific knowledge and diagnostic testing now allow for routine evaluation of ANOCA noninvasively and in the cardiac catheterization laboratory with coronary function testing (CFT). CFT includes diagnostic coronary angiography, assessment of coronary flow reserve and microcirculatory resistance, provocative testing for endothelial dysfunction and coronary vasospasm, and intravascular imaging for identification of myocardial bridging, with hemodynamic assessment as needed.

Evaluation of Ischemia with No Obstructive Coronary Arteries (INOCA) and Contemporary Applications of Cardiac Magnetic Resonance (CMR)

Ischemia with no obstructive coronary arteries (INOCA) is a relatively newly discovered ischemic phenotype that affects patients similarly to obstructive coronary artery disease (CAD) but has a unique pathophysiology and epidemiology. Patients with INOCA present with ischemic signs and symptoms but no obstructive CAD seen on coronary CTA or invasive coronary angiography, which can assess epicardial vessels. The mechanisms of INOCA can be grouped into three endotypes: coronary microvascular dysfunction, epicardial coronary vasospasm, or a combination of both. Accurate and comprehensive assessment of both epicardial and microvascular disease in suspected cases of INOCA is crucial for providing targeted therapy and improving outcomes in this underrepresented population. This review aims to clarify the complex pathophysiology of INOCA, present an overview of invasive and non-invasive diagnostic methods, and examine contemporary approaches for coronary perfusion assessment using cardiac magnetic resonance (CMR). We also explore how recent advancements in quantitative CMR can potentially revolutionize the evaluation of suspected INOCA by offering a rapid, accurate, and non-invasive diagnostic approach, thereby reducing the alarming number of cases that go undetected.

Sex-related differences in coronary vasomotor disorders: Comparisons between Western and Japanese populations

Sex-related differences in the prevalence of cardiac disorders have been elucidated beyond races. Angina/ischemia with nonobstructive coronary artery disease (AINOCA) is often observed in females. Coronary microvascular dysfunction (CMD) and coronary epicardial spasm (CES) are the principal cause of AINOCA. The clinical outcomes of Western patients with CMD were less satisfactory than expected, while the prognosis of Japanese patients with CES treated with medications including calcium channel blockers was favorable. However, the incidence and clinical features of coronary spasm endotypes were different between Western and Japanese populations. Furthermore, sex-related differences in the clinical manifestations and outcomes of patients with different spasm endotypes remain uncertain beyond race. In this article, we will review the sex differences in Japanese AINOCA patients with coronary vasomotor disorders, including CMD and CES, and compare them with those of Western patients.

Invasive coronary physiology in patients with angina and non-obstructive coronary artery disease: a consensus document from the coronary microvascular dysfunction workstream of the British Heart Foundation/National Institute for Health Research Partnership

Nearly half of all patients with angina have non-obstructive coronary artery disease (ANOCA); this is an umbrella term comprising heterogeneous vascular disorders, each with disparate pathophysiology and prognosis. Approximately two-thirds of patients with ANOCA have coronary microvascular disease (CMD). CMD can be secondary to architectural changes within the microcirculation or secondary to vasomotor dysfunction. An inability of the coronary vasculature to augment blood flow in response to heightened myocardial demand is defined as an impaired coronary flow reserve (CFR), which can be measured non-invasively, using imaging, or invasively during cardiac catheterisation. Impaired CFR is associated with myocardial ischaemia and adverse cardiovascular outcomes.The CMD workstream is part of the cardiovascular partnership between the British Heart Foundation and The National Institute for Health Research in the UK and comprises specialist cardiac centres with expertise in coronary physiology assessment. This document outlines the two main modalities (thermodilution and Doppler techniques) for estimation of coronary flow, vasomotor testing using acetylcholine, and outlines a standard operating procedure that could be considered for adoption by national networks. Accurate and timely disease characterisation of patients with ANOCA will enable clinicians to tailor therapy according to their patients' coronary physiology. This has been shown to improve patients' quality of life and may lead to improved cardiovascular outcomes in the long term.

Invasive evaluation of coronary microvascular dysfunction

Coronary microvascular dysfunction (CMD) is a prevalent cause of ischemic heart disease and is associated with poorer quality of life and worse patient outcomes. Both functional and structural abnormalities of the microcirculation can generate ischemia in the absence of epicardial stenosis or worsen concomitant obstructive coronary artery disease (CAD). The invasive assessment of CMD allows for the evaluation of the entirety of the coronary vascular tree, from the large epicardial vessels to the microcirculation, and enables the study of vasomotor function through vasoreactivity testing. The standard evaluation of CMD includes vasomotor assessment with acetylcholine, as well as flow- and resistance-derived indices calculated with either thermodilution or Doppler guidewires. Tailored treatment based upon the information gathered from the invasive evaluation of CMD has been demonstrated to reduce the burden of angina; therefore, a thorough understanding of these procedures is warranted with the aim of improving the quality of life of the patient. This review summarizes the most widespread approaches for the invasive evaluation of CMD, with a focus on patients with ischemia and non-obstructive CAD.

Coronary Vasospastic Angina: A Review of the Pathogenesis, Diagnosis, and Management

Vasospastic angina (VSA) is an under-appreciated cause of chest pain. It is characterised by transient vasoconstriction of the coronary arteries and plays a significant role in the pathogenesis of stable angina and acute coronary syndromes. Complex mechanistic pathways characterised by endothelial dysfunction and smooth muscle hypercontractility lead to a broad spectrum of clinical manifestations ranging from recurrent angina to fatal arrhythmias. Invasive provocation testing using intracoronary acetylcholine or ergonovine is considered the current gold standard for diagnosis, but there is a wide variation in protocols amongst different institutions. Conventional pharmacological therapy relies on calcium channel blockers and nitrates; however, refractory VSA has limited options. This review evaluates the pathophysiology, diagnostic challenges, and management strategies for VSA. We believe global efforts to standardise diagnostic and therapeutic guidelines will improve the outcomes for affected patients.

Safety of Provocative Testing With Intracoronary Acetylcholine and Implications for Standard Protocols

BACKGROUND

Heterogeneity in diagnostic criteria and provocation protocols has posed challenges in understanding the safety of coronary provocation testing with intracoronary acetylcholine (ACh) for the contemporary diagnosis of epicardial and microvascular spasm.

OBJECTIVES

We examined the safety of testing and subgroup differences in procedural risks based on ethnicity, diagnostic criteria, and provocation protocols.

METHODS

PubMed and Embase were searched in November 2021 to identify original articles reporting procedural complications associated with intracoronary ACh administration. The primary outcome was the pooled estimate of the incidence of major complications including death, myocardial infarction, ventricular tachycardia/fibrillation, and shock.

RESULTS

A total of 16 studies with 12,585 patients were included in the meta-analysis. The overall pooled estimate of the incidence of major complications was 0.5% (95% CI: 0.0%-1.3%) without any reports of death. Exploratory subgroup analyses revealed that the pooled incidence of major complications was significantly higher in the studies that followed the contemporary diagnosis criteria for epicardial spasm defined as ≥90% diameter reduction (1.0%; 95% CI: 0.3%-2.0%) but significantly lower in Western populations (0.0%; 95% CI: 0.0%-0.45%). The rate of positive epicardial spasm and the incidence of major complications were similar between provocation protocols using the maximum ACh doses of 100 μg and 200 μg.

CONCLUSIONS

Intracoronary ACh administration for the contemporary diagnosis of epicardial and microvascular spasm is a safe procedure. Moreover, excellent safety records are observed in Western populations primarily presenting with myocardial ischemia and/or infarction with nonobstructive coronary arteries. This study will help standardize ACh testing to improve clinical diagnosis and ensure procedural safety.

Prevalence of Coronary Microvascular Disease and Coronary Vasospasm in Patients With Nonobstructive Coronary Artery Disease: Systematic Review and Meta-Analysis

Background

A relevant proportion of patients with suspected coronary artery disease undergo invasive coronary angiography showing normal or nonobstructive coronary arteries. However, the prevalence of coronary microvascular disease (CMD) and coronary spasm in patients with nonobstructive coronary artery disease remains to be determined. The objective of this study was to determine the prevalence of coronary CMD and coronary vasospastic angina in patients with no obstructive coronary artery disease.

Methods and Results

A systematic review and meta‐analysis of studies assessing the prevalence of CMD and vasospastic angina in patients with no obstructive coronary artery disease was performed. Random‐effects models were used to determine the prevalence of these 2 disease entities. Fifty‐six studies comprising 14 427 patients were included. The pooled prevalence of CMD was 0.41 (95% CI, 0.36–0.47), epicardial vasospasm 0.40 (95% CI, 0.34–0.46) and microvascular spasm 24% (95% CI, 0.21–0.28). The prevalence of combined CMD and vasospastic angina was 0.23 (95% CI, 0.17–0.31). Female patients had a higher risk of presenting with CMD compared with male patients (risk ratio, 1.45 [95% CI, 1.11–1.90]). CMD prevalence was similar when assessed using noninvasive or invasive diagnostic methods.

Conclusions

In patients with no obstructive coronary artery disease, approximately half of the cases were reported to have CMD and/or coronary spasm. CMD was more prevalent among female patients. Greater awareness among physicians of ischemia with no obstructive coronary arteries is urgently needed for accurate diagnosis and patient‐tailored management.

Acetylcholine Use in Modern Cardiac Catheterization Laboratories: A Systematic Review

BACKGROUND

The use of acetylcholine for the diagnosis of vasospastic angina is recommended by international guidelines. However, its intracoronary use is still off-label due to the absence of safety studies. We aimed to perform a systematic review of the literature to identify adverse events related to the intracoronary administration of acetylcholine for vasoreactivity testing to fill this gap.

METHODS AND RESULTS

We conducted a systematic review of observational studies and randomized controlled trials dealing with the intracoronary administration of acetylcholine. Articles were searched in MEDLINE (PubMed) using the MeSH strategy. Three independent reviewers determined whether the studies met the inclusion and exclusion criteria. A total of 434 articles were selected. Data concerning clinical characteristics, study population, acetylcholine dosage, and adverse effects were retrieved from the articles. Overall, 71,566 patients were included, of which only 382 (0.5%) developed one adverse event, and there were no fatal events reported (0%).

CONCLUSIONS

Intracoronary administration of acetylcholine in the setting of coronary spasm provocation testing is safe and plays a central role in the evaluation of coronary vasomotion disorders, making it worthy of becoming a part of clinical practice in all cardiac catheterization laboratories.

Coronary Endothelium-Dependent Vasomotor Function After Drug-Eluting Stent and Bioresorbable Scaffold Implantation

Background Early generation drug-eluting stents (DESs) showed a high grade of coronary endothelial dysfunction that was attributed to lack of stent reendothelialization. Endothelium-dependent vasomotor response of current DESs and bioresorbable scaffolds (BRSs) remains unknown. This study sought to assess the device-related endothelial function of current devices and to correlate neointima healing with endothelial function. Methods and Results A total of 206 patients from 4 randomized trials treated with the durable-polymer everolimus-eluting Xience (n=44), bioresorbable-polymer sirolimus-eluting Orsiro (n=35), polymer-free biolimus-eluting Biofreedom (n=24), bioactive endothelial-progenitor cell-capturing sirolimus-eluting Combo DES (n=25), polymer-based everolimus-eluting Absorb (n=44), and Mg-based sirolimus-eluting Magmaris BRS (n=34) underwent endothelium-dependent vasomotor tests and optical coherence tomography imaging, as per protocol, at follow-up. Crude vasomotor responses of distal segments to low-dose acetylcholine (10^-6 mol/L) were different between groups: bioresorbablepolymer DEShad the worst (-8.4%±12.6%) and durable-polymer DES had the most physiologic (-0.4%±11.8%; P=0.014). High-dose acetylcholine (10^-4 mol/L) showed similar responses between groups (ranging from -10.8%±11.6% to -18.1%±15.4%; P=0.229). Device healing was different between devices. Uncovered struts ranged from 6.3%±7.1% (bioresorbable-polymer DES) to 2.5%±4.5% (bioactive DES; P=0.056). In multivariate models, endothelium-dependent vasomotor response was associated with age, bioresorbable-polymer DES, and angiographic lumen loss, but not with strut coverage nor plaque type. Endothelial dysfunction (defined as ≥4% vasoconstriction) was observed in 46.6% of patients with low-dose and 68.9% with high-dose acetylcholine, without differences between groups. Conclusions At follow-up, endothelial dysfunction was frequently observed in distal segments treated with current stents without remarkable differences between devices. Although neointima healing was different between devices, poor healing was not associated with endothelial dysfunction.

Sex Differences in Coronary Function Test Results in Patient With Angina and Nonobstructive Disease

Introduction: Invasive coronary function testing (CFT) has become the recommended diagnostic tool to assess the various endotypes of coronary vasomotor dysfunction in patients with angina and no obstructive coronary artery disease (ANOCA), which has implications for therapy and prognosis. Although the expanding performance of CFT is leading to increased knowledge of coronary vasomotor dysfunction, little is known about sex-related differences in the results of comprehensive CFT.

Methods: We conducted a prospective study of all consecutive patients with ANOCA that underwent clinically indicated CFT in a tertiary interventional from February 2019 to February 2021. CFT consisted of acetylcholine testing to diagnose epicardial or microvascular spasm, and adenosine testing to diagnose CMD. CMD was defined as an index of microvascular resistance (IMR) ≥ 25 and/or coronary flow reserve (CFR) < 2.0.

Results: In total, 228 women and 38 men underwent CFT. No differences in traditional risk factors were seen, but women had a higher prevalence of migraine (45 vs. 14%, p = 0.001). Men more often had a history of percutaneous coronary intervention (12 vs. 49%, p = 0.001). We found no difference in clinical presentation. Coronary vasomotor dysfunction was present in 95% of men and 88% of women (p = 0.25), but males show more often epicardial spasm and less microvascular spasm than women (63 vs. 42% and 29 vs. 40% respectively, p = 0.039). Impaired CFR was more prevalent among females (6 vs 20%, p = 0.033). IMR [median of 23 (15–32) vs. 19 (13–25), p = 0.08] did not differ between the sexes.

Conclusion: Men undergoing CFT show a comparable prevalence of coronary vascular dysfunction as women. However, men have a higher prevalence of epicardial spasm and a lower prevalence of microvascular spasm compared with women. An impaired CFR was more often present in women, with an equally impairment of IMR.