Presence of Coronary Endothelial Dysfunction, Coronary Vasospasm, and Adenosine-Mediated Vasodilatory Disorders in Patients With Ischemia and Nonobstructive Coronary Arteries

Rationale and design of the ILIAS ANOCA clinical trial: A blinded-arm controlled trial for routine ad-hoc coronary function testing

BACKGROUND

Angina with nonobstructive coronary arteries (ANOCA) is a major cause of chronic coronary syndromes, affecting nearly half of patients with anginal symptoms who undergo invasive coronary angiography. ANOCA may lead to substantial symptom burden, increased risk of adverse cardiac events, increased healthcare utilization due to ongoing symptoms, repeat hospitalizations, and invasive testing. The pathophysiology of ANOCA often involves a variety of coronary disorders, such as coronary microvascular dysfunction, epicardial or microvascular vasospasm and endothelial dysfunction. While coronary function testing (CFT) can identify each of these specific endotypes, in current practice it is used as a second- or third-line diagnostic tool, delaying diagnosis which contributes to persistent symptoms and diminished quality of life. The ILIAS ANOCA clinical trial aims to enhance understanding and management of ANOCA through early routine CFT-guided management.

METHODS

After exclusion of obstructive coronary artery disease, eligible patients undergo comprehensive CFT, and will be randomized to blinding of the CFT results (control group) or disclosure of the CFT results combined with a tailored medical therapy escalation plan (intervention group). The control group will be unblinded after 1 year. The primary outcome is the mean difference in the within-subject change in Seattle Angina Questionnaire (SAQ) summary score between the groups at 6 months from baseline. Secondary outcomes include differences in SAQ-summary score and additional health-status and quality of life questionnaires at 12 and 24 months from baseline.

CLINICAL TRIAL REGISTRATION

International Clinical Trials Registry Platform identifier NL-OMON20739.

Invasive coronary function testing in clinical practice: Implementing the 2024 ESC guidelines on chronic coronary syndromes

Angina with non-obstructive coronary arteries (ANOCA) is increasingly recognized as a significant aspect of chronic coronary syndromes. These patients frequently experience recurrent angina, resulting in high healthcare costs and impaired quality of life. Invasive coronary function testing (ICFT) is able to identify ANOCA endotypes, which can guide treatment and improve quality of life. Despite Class II recommendations for invasive microvascular assessments in the previous 2019 European Society of Cardiology (ESC) Guidelines, ICFT has yet to translate into widespread clinical practice. Patients with ANOCA experience poor quality of life and reduced functional capacity, highlighting the need for earlier ICFT implementation. The 2024 ESC Guidelines now strongly recommend ICFT (Class I, level of evidence B) for patients with non-obstructive coronary arteries and persistent angina despite optimal medical therapy, and for confirming or excluding ANOCA in patients with uncertain diagnoses on non-invasive testing (Class I, level of evidence B). Consequently, a standardized approach to optimize the management of ANOCA patients is warranted. Therefore, this review aims to provide interventional cardiologists with a contemporary review of the literature and a practical guideline on implementation of ICFT. It will discuss the following subjects: the definitions of the different endotypes, an example of an ICFT protocol, discontinuation of medication prior to ICFT, use of radial cocktail, target vessel for testing, acetylcholine injection techniques and rechallenge, adenosine injection techniques, the order of testing, the interpretation of ICFT, safety and feasibility, and the pharmacological treatment.

Intracoronary acetylcholine for vasospasm provocation in women with ischemia and no obstructive coronary artery disease

Objectives

To evaluate the utility of higher dose intracoronary acetylcholine (ACh) during invasive coronary function testing (CFT) in women with suspected ischemia and no obstructive coronary artery disease (INOCA) for detection of epicardial vasospasm, relation to quality of life (QoL) and the presence of scar by late gadolinium enhancement (LGE) on cardiac magnetic resonance imaging (CMRI).

Background

CFT is an established method for diagnosis of coronary microvascular dysfunction (CMD). The utility of epicardial vasospasm provocation testing with higher dose ACh infusion is not fully understood.

Methods

Women with suspected INOCA undergoing invasive CFT were enrolled in the Women's Ischemia Syndrome Evaluation-Pre-Heart Failure with Preserved Ejection Fraction (WISE Pre-HFpEF) study (NCT03876223). Incremental infusions of 0.364, 36.4 μg and 108 μg ACh were used for vasospasm provocation. Vasospasm was defined as ≥75 % artery diameter reduction compared to post-nitroglycerin diameter and related to QoL and LGE on CMRI.

Results

Among 73 women (56 ± 11 years), epicardial vasospasm was detected in 17 (23 %). Among women with vasospasm, the vast majority (94 %) had coronary endothelial dysfunction and few (12 %) had other abnormal CFT measures. Those with vasospasm had more nocturnal angina symptoms, calcium channel blocker use, poorer QoL (all p = 0.001) and disease perception (p = 0.02) than those without. LGE scar by CMRI was not associated with vasospasm (p = 0.22).

Conclusions

Among women with suspected INOCA, intracoronary Ach spasm testing provoked epicardial vasospasm in one fourth. Women with epicardial vasospasm overwhelmingly had concomitant endothelial dysfunction, worse QoL but not more frequent myocardial scar on CMRI.

The impact of high microvascular resistance on coronary wave energetics depends on coronary microvascular functionality

Aims

The pathophysiological relevance of high hyperemic microvascular resistance (hMR) in stable coronary artery disease is controversial. Using wave intensity analysis (WIA, defined as the product of the time derivatives of the coronary pressure and velocity), we aim to compare the impact of high hMR on coronary wave energetics with respect to coronary microvascular dysfunction (CMD), defined as reduced coronary flow reserve (CFR < 2.5), in unobstructed arteries.

Methods and results

The study population (n = 258, mean age = 68 ± 10 years, 73% male) had a high cardiovascular risk profile including dyslipidemia (88%), hypertension (70%), smoking (55%) and diabetes (28%). The mean fractional flow reserve was 0.89 ± 0.05. Vessels (n = 312) were divided into four endotypes: no CMD-low hMR (CFR ≥ 2.5, hMR < 2.5 mmHg.s.cm-1), Functional CMD (CFR < 2.5, hMR < 2.5 mmHg.s.cm-1), Structural CMD (CFR < 2.5, hMR ≥ 2.5 mmHg.s.cm-1), and no CMD-high hMR (CFR ≥ 2.5, hMR ≥ 2.5 mmHg.s.cm-1). The no CMD-high hMR endotype had the lowest mean resting velocity (bAPV = 10 ± 3 cm.s-1  P < 0.001), highest mean basal microvascular resistance (bMR = 9 ± 2 mmHg/cm.s-1  P < 0.001) amongst all endotypes, yet, it had reference-level CFR, microvascular resistance reserve and resistive reserve ratio (P > 0.05 for all compared to no CMD-low hMR), unlike CMD endotypes (P < 0.05 compared to CMD endotypes). The no CMD-high hMR endotype exhibited the highest hyperemic increase in the accelerating wave energy proportion (AEP) (13% ± 13%, P = 0.042), indicating an intact autoregulatory response. Only in the CMD endotypes, high hMR was associated with reduced AEP (r = -0.229, P < 0.001), unlike no CMD endotypes (P = 0.383).

Conclusion

High hMR alone is not a definitive CMD marker. In line with the adaptive high hMR hypothesis, increased hMR does not necessarily limit augmentation of AEP, and is associated with robust autoregulatory capacity in vessels with preserved CFR. Cardiologists should be alert to a potential adaptive no CMD-high hMR endotype to avoid misdiagnosis.

Registration

NCT02328820.

Prediction of cardiac allograft vasculopathy using splenic switch-off on myocardial PET

BACKGROUND

Heart transplantation (HTx) is a definitive therapy for refractory heart failure. Cardiac allograft vasculopathy (CAV), characterized by diffuse arteriopathy involving the epicardial coronary arteries and microvasculature, is the major cause of death for patients with HTx. 13N-ammonia positron emission tomography (NH3-PET) can offer diagnostic and prognostic utility for CAV. The splenic switch-off (SSO) detected in NH3-PET is a hemodynamic indicator of favorable response to adenosine. We hypothesized that both CAV and SSO reflected a pathology that progresses in parallel with systemic vascular endothelial dysfunction. Therefore, we quantitatively evaluated splenic adenosine reactivity measured using NH3-PET as an index of endothelial function, and examined its predictability for CAV.

METHODS

Forty-eight patients who underwent NH3-PET after HTx were analyzed. The spleen ratio was calculated as the mean standardized uptake value, measured by placing an ROI on the spleen, at stress divided by that at rest. SSO was defined by a cutoff determined using receiver operating characteristic (ROC) analysis for the spleen ratio. The endpoint was appearance or progression of CAV. Predictability of SSO was analyzed using Kaplan-Meier analysis.

RESULTS

The endpoint occurred in 9 patients during a mean follow-up of 45 ± 17 months. ROC curve analysis demonstrated a cutoff of 0.94 for spleen ratio. Patients without SSO displayed a significantly higher CAV rate than those with SSO (p = 0.022).

CONCLUSIONS

SSO reflects the endothelial function of systemic blood vessels and was a predictor of CAV in patients with HTx.

Coronary Endothelial Dysfunction and Vasomotor Dysregulation in Myocardial Bridging

Myocardial bridging (MB), a congenital variant where a coronary artery segment is tunneled within the myocardium, is increasingly recognized as a contributor to coronary endothelial and vasomotor dysfunction. Beyond the hallmark systolic compression observed on angiography, MB disrupts endothelial integrity, impairs the release of vasoactive substances, and induces vasomotor abnormalities. These effects exacerbate ischemic symptoms and predispose to atherosclerosis in the proximal segment, particularly in conditions such as ischemia/myocardial infarction with nonobstructive coronary arteries. Recent studies underscore MB's association with coronary vasospasm, microvascular endothelial dysfunction, and adverse cardiovascular outcomes, including sudden cardiac death. These findings highlight the interplay between MB's structural anomalies and functional impairments, with factors such as the bridge's length, depth, and orientation influencing its hemodynamic significance. Advances in imaging and coronary physiology assessment, including acetylcholine testing and stress diastolic fractional flow reserve/iFR/RFR, have enhanced diagnostic precision. This review explores the multifaceted impact of MB on coronary physiology, emphasizing its role in endothelial dysfunction and vasomotor regulation. Recognizing MB's contribution to cardiovascular disease is essential for accurate diagnosis and tailored management strategies aimed at mitigating ischemic risk and improving patient outcomes.

Coronary Myocardial Bridge Updates: Anatomy, Pathophysiology, Clinical Manifestations, Diagnosis, and Treatment Options

Myocardial bridging is a frequent anomaly of the heart in humans and other animals. A myocardial bridge is typically characterized by the systolic narrowing seen with traditional catheter angiography, but this abnormality is not by itself a sign of ischemia or the need for intervention. In particular, transient spontaneous angina must be corroborated by reproducible narrowing during acetylcholine testing; this narrowing occurs during resting conditions and is responsive to nitroglycerin administration. Ischemia in myocardial bridging can result from acquired arterial wall disease (coronary artery atherosclerotic disease) or from instances of coronary spasm. Clinical evaluation should seek to identify baseline features such as myocardial bridge thickness (by using computerized axial tomography or intravascular ultrasonography) and the severity of systolic compression or reproducible spasticity (by administering acetylcholine). Nuclear myocardial scintigraphy is usually negative in patients with isolated myocardial bridging. Spastic coronary hyperactivity must be treated initially with antispasmodic medications, such as calcium channel blockers and nitrates, rather than by percutaneous stent placement or bypass surgery. Only exceptionally prolonged and critically severe spasm can induce intraluminal clotting and acute myocardial infarction. Recognizing the exceptionality and variability of ischemic presentations related to myocardial bridging is essential, as is establishing appropriate investigational methods for each of these facets of the condition.

Assessment of coronary endothelial dysfunction using contemporary coronary function testing

BACKGROUND

The established diagnosis of coronary endothelial dysfunction (CED) is through the response to low-dose acetylcholine during invasive coronary function testing (CFT). Current diagnostic criteria encompass deficient epicardial vasodilation and/or insufficient increase in coronary blood flow (CBF) calculated from additional Doppler flow velocity measurements. The aim is to evaluate the diagnostic yield of using angiographic epicardial vasomotion and CBF as single criteria for diagnosing CED during CFT.

METHODS

A total of 110 patients with angina and non-obstructive coronary arteries who underwent clinically indicated CFT were included. CED was defined as any reduction in epicardial diameter through quantitative coronary angiography and/or < 50 % increase in CBF compared to baseline after low-dose acetylcholine.

RESULTS

Based on current diagnostic criteria, 78 % of patients (N = 86/110) was diagnosed with CED. When only considering epicardial diameter, 24 % CED (N = 21/86) and 50 % severe CED diagnoses (N = 19/38) were missed. When only considering CBF, 27 % CED (N = 23/86) and 18 % severe CED diagnoses (N = 7/38) were missed. A similar diagnostic yield for CED detection was found for both parameters (OR: 0.913, 95 %CI 0.481-1.726, p = 0.763). The incidence of CFT diagnoses was comparable among all groups.

CONCLUSIONS

As single parameters, both epicardial diameter and CBF were ineffective in accurately diagnosing CED compared to the current diagnostic criteria. Combining both parameters is necessary to diagnose the complete spectrum of CED, as missed diagnoses of deficient CBF responses (e.g., microvascular CED) and epicardial vasomotion (e.g., epicardial CED) might occur when relying on these parameters as single diagnostic criteria for CED.

Prognostic significance of myocardial ischaemia during exercise echocardiography in the absence of angiographic evidence of obstructive coronary disease

Aims

We studied the prognostic significance of myocardial ischaemia during exercise stress echocardiography (ExE) in the absence of angiographic evidence of obstructive coronary artery disease (CAD) in a contemporary cohort of patients.

Methods and results

We retrospectively enrolled 84 patients who underwent ExE and had exercise-induced myocardial ischaemia followed by angiographic coronary evaluation. Fifty-one (61%) patients had non-obstructive CAD (iNOCAD), and 33 (39%) had normal coronaries (iNC). iNC and NOCAD patients were propensity matched to 99 and 153 patients with non-ischaemic ExE, respectively. Compared to iNOCAD, iNC patients were younger (60.9 ± 10.4 vs. 68 ± 8.9 years, P = 0.002) and predominantly women (76% vs. 47%, P = 0.009). Ejection fraction (57 ± 9.4 vs. 56.4 ± 6, P = 0.776) as well as other clinical and demographic variables were similar. During median follow-up of 3.2 years, there were 27 composite adverse cardiovascular events (1 death, 10 acute chest pain events, 2 strokes, and 21 cardiac hospitalizations). iNC was associated with a higher risk of acute chest pain (HR: 19.0, 95% CI: 3.7-93) and the composite adverse outcome (HR: 3.3, 95% CI: 1.7-6.6), compared to matched patients. Similarly, iNOCAD was associated with a higher risk of the composite outcome (HR: 2.2, 95% CI: 1.2-4.2).

Conclusion

Ischaemic ExE in the absence of angiographically obstructive CAD carries an elevated risk of adverse cardiovascular events necessitating medical optimization and close follow-up for progression.

Dose-related effect of acetylcholine on human gingival blood flow

BACKGROUND

This study investigates the dose-response relationship of acetylcholine (ACh) on healthy human gingival blood flow (GBF). Understanding this dose-response relationship contributes to studying vasodilatory mechanisms in various pathological conditions.

METHODS

The study involved 22 young healthy men (21 - 32 years) to investigate the dose-response relationship of ACh on GBF. Semi-circular wells were created on the labial surface of the upper right second incisor (FDI #12) and upper left first incisor (FDI #21), including the gingival sulcus, for the application of drugs. ACh-chloride solutions at 0.1, 1, and 10 mg/mL were administered to the gingival sulcus of tooth FDI #12 with a Hamilton syringe. Physiological saline was applied on the contralateral side to FDI #21 as a control. The GBF was measured non-invasively by the laser speckle contrast imaging method in four 1mm high adjacent regions: coronal, midway1, midway2, and apical, and was expressed in a laser speckle perfusion unit (LSPU). After the baseline blood flow recording, ACh doses were applied sequentially, with washout periods in between. Data were statistically analyzed using a linear mixed model.

RESULTS

The GBF did not change on the saline site throughout the experiment. The GBF was significantly higher at the coronal region after all ACh doses (baseline: 218±31 LSPU, and 227±38 LSPU p < 0.05, 239±40 LSPU p < 0.001, 291±54 LSPU p < 0.001, respectively) compared to the saline. It was also elevated following 1 and 10 mg/mL at the midway1 (245±48 LSPU, p < 0.05, 293±65 LSPU p < 0.001). At midway2 and apical, only the 10 mg/mL dose was effective (285±71 LSPU, p < 0.001; 302±82 LSPU, p < 0.001).

CONCLUSIONS

Our findings suggest a dose-dependent vasodilation to ACh, emphasizing its role in human gingival microcirculation. Only the 10 mg/mL ACh could evoke remote vasodilation 3 mm from the application. The described method could facilitate the investigation of endothelium-dependent vasodilation in disorders affecting microcirculation, such as periodontitis or diabetes.

Contemporary Functional Coronary Angiography: An Update

Functional coronary angiography (FCA) is a novel modality for assessing the physiology of coronary lesions, going beyond anatomical visualization by traditional coronary angiography. FCA incorporates indices like fractional flow reserve (FFR) and instantaneous wave-free ratio (IFR), which utilize pressure measurements across coronary stenoses to evaluate hemodynamic impacts and to guide revascularization strategies. In this review, we present traditional and evolving modalities and uses of FCA. We will also evaluate the existing evidence and discuss the applicability of FCA in various clinical scenarios. Finally, we provide insight into emerging evidence, current challenges, and future directions in FCA.

Prognostic Implications of Resistive Reserve Ratio in Patients With Nonobstructive Coronary Artery Disease With Myocardial Bridging

BACKGROUND

Myocardial bridging (MB) is accompanied by the dynamic extravascular compression of epicardial coronary arteries, leading to intracoronary hemodynamic disturbance with abnormal coronary flow profiles. We aimed to evaluate the prognostic implications of resistive reserve ratio (RRR), a composite measure of flow and pressure parameters that represents the vasodilatory capacity of the coronary arteries, in patients with angina with nonobstructive coronary artery disease (ANOCA) and MB, in comparison with coronary flow reserve (CFR).

METHODS AND RESULTS

In this retrospective cohort study, we included patients with ANOCA who underwent coronary reactivity testing, where MB was identified by transient constriction in coronary artery segments between systole and diastole. Abnormal CFR and RRR were defined as <2.5 and <2.62, respectively. Major adverse cardiac events, including cardiovascular death, stroke, myocardial infarction, heart failure, and late revascularization, served as outcomes. Among 1251 patients with ANOCA, 191 (15.3%) had MB. The prevalence of abnormal CFR or RRR was not significantly different between patients with and without MB (P=0.144 and P=0.398, respectively). Over a median follow-up time of 6.9 years, abnormal RRR predicted major adverse cardiac events in patients with MB (hazard ratio [HR], 4.38 [95% CI, 1.71-11.21]; P=0.002) and without MB (HR, 1.91 [95% CI, 1.38-2.64]; P<0.001). Abnormal CFR predicted major adverse cardiac events in patients without MB (HR, 2.15 [95% CI, 1.54-3.00]; P<0.001), whereas it was not predictive of major adverse cardiac events in patients with MB (HR, 2.29 [95% CI, 0.93-5.65]; P=0.073).

CONCLUSIONS

In patients with ANOCA and MB, impaired RRR was superior to impaired CFR in distinguishing patients at a higher risk of future adverse events, suggesting that RRR may serve as a risk stratification tool in patients with MB and ANOCA.

Evaluating Ischemic Heart Disease in Women: Focus on Angina With Nonobstructive Coronary Arteries (ANOCA)

Ischemic heart disease (IHD) is common in women, and cardiovascular disease is a leading cause of morbidity and mortality. While obstructive coronary artery disease is the most common form of IHD, millions of women suffer from angina with nonobstructive coronary arteries (ANOCA), an umbrella term encompassing multiple nonatherosclerotic disorders of the coronary tree. The underlying pathology leading to ischemia in these syndromes may be challenging to diagnose, leaving many women without a diagnosis despite persistent symptoms that impact quality of life and adversely affect long-term cardiovascular prognosis. In the last decade, there have been significant advances in the recognition and diagnostic evaluation of ANOCA. Despite these advances, the standard approach to evaluating suspected IHD in women continues to focus predominantly on the assessment of atherosclerotic coronary artery disease, leading to missed opportunities to accurately diagnose and treat underlying coronary vasomotor disorders. The goal of this review is to describe advances in diagnostic testing that can be used to evaluate angina in women and present a pragmatic diagnostic algorithm to guide evaluation of ANOCA in symptomatic patients. The proposed approach for the assessment of ANOCA is consistent with prior expert consensus documents and guidelines but is predicated on the medical interview and pretest probability of disease to inform a personalized diagnostic strategy.

Multivessel Coronary Function Testing Increases Diagnostic Yield in Patients With Angina and Nonobstructive Coronary Arteries

BACKGROUND

Invasive CFT is the gold standard for diagnosing coronary vasomotor dysfunction in patients with ANOCA. Most institutions recommend only testing the left coronary circulation. Therefore, it is unknown whether testing multiple coronary territories would increase diagnostic yield.

OBJECTIVES

The aim of this study was to evaluate the diagnostic yield of multivessel, compared with single-vessel, invasive coronary function testing (CFT) in patients with angina and nonobstructive coronary arteries (ANOCA).

METHODS

Multivessel CFT was systematically performed in patients with suspected ANOCA. Vasoreactivity testing was performed using acetylcholine provocation in the left (20 to 200 μg) and right (20 to 80μg) coronary arteries. A pressure-temperature sensor guidewire was used for coronary physiology assessment in all three epicardial vessels.

RESULTS

This multicenter study included a total of 228 vessels from 80 patients (57.8 ± 11.8 years of age, 60% women). Compared with single-vessel CFT, multivessel testing resulted in more patients diagnosed with coronary vasomotor dysfunction (86.3% vs 68.8%; P = 0.0005), coronary artery spasm (60.0% vs 47.5%; P = 0.004), and CMD (62.5% vs 36.3%; P < 0.001). Coronary artery spasm (n = 48) predominated in the left coronary system (n = 38), though isolated right coronary spasm was noted in 20.8% (n = 10). Coronary microvascular dysfunction (CMD), defined by abnormal index of microcirculatory resistance and/or coronary flow reserve, was present 62.5% of the cohort (n = 50). Among the cohort with CMD, 27 patients (33.8%) had 1-vessel CMD, 15 patients (18.8%) had 2-vessel CMD, and 8 patients (10%) had 3-vessel CMD. CMD was observed at a similar rate in the territories supplied by all 3 major coronary vessels (left anterior descending coronary artery = 36.3%, left circumflex coronary artery = 33.8%, right coronary artery = 31.3%; P = 0.486).

CONCLUSIONS

Multivessel CFT resulted in an increased diagnostic yield in patients with ANOCA compared with single-vessel testing. The results of this study suggest that multivessel CFT has a role in the management of patients with ANOCA.

Comparison of the Diagnostic Yield of Intracoronary Acetylcholine Infusion and Acetylcholine Bolus Injection Protocols During Invasive Coronary Function Testing

Coronary endothelial dysfunction (CED) and coronary artery spasm (CAS) are causes of angina with no obstructive coronary arteries in patients. Both can be diagnosed by invasive coronary function testing (ICFT) using acetylcholine (ACh). This study aimed to evaluate the diagnostic yield of a 3-minute ACh infusion as compared with a 1-minute ACh bolus injection protocol in testing CED and CAS. We evaluated 220 consecutive patients with angina and no obstructive coronary arteries who underwent ICFT using continuous Doppler flow measurements. Per protocol, 110 patients were tested using 3-minute infusion, and thereafter 110 patients using 1-minute bolus injections, because of a protocol change. CED was defined as a <50% increase in coronary blood flow or any epicardial vasoconstriction in reaction to low-dose ACh and CAS according to the Coronary Vasomotor Disorders International Study Group (COVADIS) criteria, both with and without T-wave abnormalities, in reaction to high dose ACh. The prevalence of CED was equal in both protocols (78% vs 79%, p = 0.869). Regarding the endotypes of CAS according to COVADIS, the equivocal endotype was diagnosed less often in the 3 vs 1-minute protocol (24% vs 44%, p = 0.004). Including T-wave abnormalities in the COVADIS criteria resulted in a similar diagnostic yield of both protocols. Hemodynamic changes from baseline to the low or high ACh doses were comparable between the protocols for each endotype. In conclusion, ICFT using 3-minute infusion or 1-minute bolus injections of ACh showed a similar diagnostic yield of CED. When using the COVADIS criteria, a difference in the equivocal diagnosis was observed. Including T-wave abnormalities as a diagnostic criterion reclassified equivocal test results into CAS and decreased this difference. For clinical practice, we recommend the inclusion of T-wave abnormalities as a diagnostic criterion for CAS and the 1-minute bolus protocol for practicality.

Ischemia but no obstructive coronary artery disease: more than meets the eye

Symptomatic women with angina are more likely to have ischemia with no obstructive coronary arteries (INOCA) compared to men. In both men and women, the finding of INOCA is not benign and is associated with adverse cardiovascular events, including myocardial infarction, heart failure and angina hospitalizations. Women with INOCA have more angina and a lower quality of life compared to men, but they are often falsely reassured because of a lack of obstructive coronary artery disease (CAD) and a perception of low risk. Coronary microvascular dysfunction (CMD) is a key pathophysiologic contributor to INOCA, and non-invasive imaging methods are used to detect impaired microvascular flow. Coronary vasospasm is another mechanism of INOCA, and can co-exist with CMD, but usually requires invasive coronary function testing (CFT) with provocation testing for a definitive diagnosis. In addition to traditional heart disease risk factors, inflammatory, hormonal and psychological risk factors that impact microvascular tone are implicated in INOCA. Treatment of risk factors and use of anti-atherosclerotic and anti-anginal medications offer benefit. Increasing awareness and early referral to specialized centers that focus on INOCA management can improve patient-oriented outcomes. However, large, randomized treatment trials to investigate the impact on major adverse cardiovascular events (MACE) are needed. In this focused review, we discuss the prevalence, pathophysiology, presentation, diagnosis and treatment of INOCA.

Nicorandil alleviates cardiac microvascular ferroptosis in diabetic cardiomyopathy: Role of the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway

Mitochondria-associated ferroptosis exacerbates cardiac microvascular dysfunction in diabetic cardiomyopathy (DCM). Nicorandil, an ATP-sensitive K+ channel opener, protects against endothelial dysfunction, mitochondrial dysfunction, and DCM; however, its effects on ferroptosis and mitophagy remain unexplored. The present study aimed to assess the beneficial effects of nicorandil against endothelial ferroptosis in DCM and the underlying mechanisms. Cardiac microvascular perfusion was assessed using a lectin perfusion assay, while mitophagy was assessed via mt-Keima transfection and transmission electron microscopy. Ferroptosis was examined using mRNA sequencing, fluorescence staining, and western blotting. The mitochondrial localization of Parkin, ACSL4, and AMPK was determined via immunofluorescence staining. Following long-term diabetes, nicorandil treatment improved cardiac function and remodeling by alleviating cardiac microvascular injuries, as evidenced by the improved microvascular perfusion and structural integrity. mRNA-sequencing and biochemical analyses showed that ferroptosis occurred and Pink1/Parkin-dependent mitophagy was suppressed in cardiac microvascular endothelial cells after diabetes. Nicorandil treatment suppressed mitochondria-associated ferroptosis by promoting the Pink1/Parkin-dependent mitophagy. Moreover, nicorandil treatment increased the phosphorylation level of AMPKα1 and promoted its mitochondrial translocation, which further inhibited the mitochondrial translocation of ACSL4 via mitophagy and ultimately suppressed mitochondria-associated ferroptosis. Importantly, overexpression of mitochondria-localized AMPKα1 (mitoAα1) shared similar benefits with nicorandil on mitophagy, ferroptosis and cardiovascular protection against diabetic injury. In conclusion, the present study demonstrated the therapeutic effects of nicorandil against cardiac microvascular ferroptosis in DCM and revealed that the mitochondria-localized AMPK-Parkin-ACSL4 signaling pathway mediates mitochondria-associated ferroptosis and the development of cardiac microvascular dysfunction.

Silent Myocardial Ischemia Revisited, Another Silent Killer, Emphasis on the Diagnostic Value of Stress Echocardiography with Focused Update and Review

Silent myocardial ischemia (SMI) is a relatively common phenomenon in patients with coronary artery disease (CAD). The original description of SMI dates back to the 1970s. We performed an extensive search of the literature starting from 2000, using MEDLINE or PubMed, and 676 documents were analyzed, and only 45 articles found suitable for the study were selected. Data regarding the prevalence and risk factors of SMI were discussed, along with the different mechanistic processes behind it; also, methods for screening and diagnosis are exposed, namely electrocardiographic stress test, stress echocardiography, and single-photon emission computed tomography (SPECT). The silent nature of the condition presumes that patients are diagnosed at a more advanced stage, and screening high-risk patients for early management is essential. Education of patients is necessary, and medical management along with cardiac rehabilitation is valid for mild cases, whereas patients with moderate-to-severe myocardial ischemia might require a more invasive approach. SMI is relatively common, diagnostic approach offers data regarding the presence of ischemia along with its anatomic extent, providing important prognostic value. Given its silent and critical nature, future directions for better screening and management must be searched and implemented extensively.

Pharmacotherapy in patients with vasomotor disorders

Background

Anginal symptoms in patients with non-obstructive coronary artery disease are frequently related to vasomotor disorders of the coronary circulation. Although frequently overlooked, a distinct diagnosis of different vasomotor disorders can be made by intracoronary function testing. Early detection and treatment seems beneficial, but little evidence is available for the medical treatment of these disorders. Nevertheless, there are several pharmacotherapeutic options available to treat these patients and improve quality of life.

Methods & findings

We performed an extensive yet non-systematic literature search to explore available pharmacotherapeutic strategies for addressing vasomotor disorders in individuals experiencing angina and non-obstructive coronary artery disease. This article presents a comprehensive overview of therapeutic possibilities for patients exhibiting abnormal vasoconstriction (such as spasm) and abnormal vasodilation (like coronary microvascular dysfunction).

Conclusion

Treatment of vasomotor disorders can be very challenging, but a general treatment algorithm based on the existing evidence and the best available current practice is feasible.

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.

Endothelial dysfunction, platelet hyperactivity, hypertension, and the metabolic syndrome: molecular insights and combating strategies

Metabolic syndrome (MetS) is a multifaceted condition that increases the possibility of developing atherosclerotic cardiovascular disease. MetS includes obesity, hypertension, dyslipidemia, hyperglycemia, endothelial dysfunction, and platelet hyperactivity. There is a concerning rise in the occurrence and frequency of MetS globally. The rising incidence and severity of MetS need a proactive, multipronged strategy for identifying and treating those affected. For many MetS patients, achieving recommended goals for healthy fat intake, blood pressure control, and blood glucose management may require a combination of medicine therapy, lifestyles, nutraceuticals, and others. However, it is essential to note that lifestyle modification should be the first-line therapy for MetS. In addition, MetS requires pharmacological, nutraceutical, or other interventions. This review aimed to bring together the etiology, molecular mechanisms, and dietary strategies to combat hypertension, endothelial dysfunction, and platelet dysfunction in individuals with MetS.

Efficacy and safety of the endothelin-1 receptor antagonist macitentan in epicardial and microvascular vasospasm; a proof-of-concept study

Background

Treatment of patients diagnosed with angina due to epicardial or microvascular coronary artery spasm (CAS) is challenging because patients often remain symptomatic despite conventional pharmacological therapy. In this prospective, randomized, double-blind, placebo-controlled, sequential cross-over proof-of-concept study, we compared the efficacy and safety of macitentan, a potent inhibitor of the endothelin-1 receptor, to placebo in symptomatic patients with CAS despite background pharmacological treatment.

Methods

Patients with CAS diagnosed by invasive spasm provocation testing with >3 anginal attacks per week despite pharmacological treatment were considered for participation. Participants received either 10 mg of macitentan or placebo daily for 28 days as add-on treatment. After a wash-out period patients were crossed over to the alternate treatment arm. The primary endpoint was the difference in anginal burden calculated as [1] the duration (in minutes) * severity (on a Visual Analogue Scale (VAS) pain scale 1-10); and [2] the frequency of angina attacks * severity during medication use compared to the run-in phase.

Results

28 patients of whom 22 females (79%) and a mean age of 55.3 ± 7.6 completed the entire study protocol (epicardial CAS n = 19 (68), microvascular CAS n = 9 (32)). Change in both indices of anginal burden were not different during treatment with add-on macitentan as compared to add-on placebo (duration*severity: -9 [-134 78] vs -45 [-353 11], p = 0.136 and frequency*severity: -1.7 [-5.8 1.2] vs -1.8 [-6.2 0.3], p = 0.767). The occurrence and nature of self-reported adverse events were closely similar between the treatment phase with macitentan and placebo.

Conclusion

In patients with angina due to epicardial or microvascular CAS despite background pharmacological treatment, 28 days of add-on treatment with the ET-1 receptor antagonist, macitentan 10 mg daily, did not reduce anginal burden compared to add-on treatment with placebo.Trial Registrationhttps://trialsearch.who.int/, Identifier: EUCTR2018-002623-42-NL. Registration date: 20 February 2019.

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 Microvascular Dysfunction: What Clinicians and Investigators Should Know

PURPOSE OF REVIEW

Abnormal structure and function of the coronary microvasculature have been implicated in the pathophysiology of multiple cardiovascular disease processes. This article reviews recent research progress related to coronary microvascular dysfunction (CMD) and salient clinical takeaways.

RECENT FINDINGS

CMD is prevalent in patients with signs and symptoms of ischemia and no obstructive epicardial coronary artery disease (INOCA), particularly in women. CMD is associated with adverse outcomes, including most frequently the development of heart failure with preserved ejection fraction. It is also associated with adverse outcomes in patient populations including hypertrophic cardiomyopathy, dilated cardiomyopathy, and acute coronary syndromes. In patients with INOCA, stratified medical therapy guided by invasive coronary function testing to define the subtype of CMD leads to improved symptoms. There are invasive and non-invasive methodologies to diagnose CMD that provide prognostic information and mechanistic information to direct treatment. Available treatments improve symptoms and myocardial blood flow; ongoing investigations aim to develop therapy to improve adverse outcomes related to CMD.

Ischemia With Nonobstructive Coronary Artery Disease: Concept, Assessment, and Management

In daily clinical practice, physicians often encounter patients with angina or those with evidence of myocardial ischemia from noninvasive tests but not having obstructive coronary artery disease. This type of ischemic heart disease is referred to as ischemia with nonobstructive coronary arteries (INOCA). INOCA patients often suffer from recurrent chest pain without adequate management and are associated with poor clinical outcomes. There are several endotypes of INOCA, and each endotype should be treated based on its specific underlying mechanism. Therefore, identifying INOCA and discriminating its underlying mechanisms are important issues and of clinical interest. Invasive physiologic assessment is the first step in the diagnosis of INOCA and discriminating the underlying mechanism; additional provocation tests help physicians identify the vasospastic component in INOCA patients. Comprehensive information acquired from these invasive tests can provide a template for mechanism-specific management for patients with INOCA.

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

BACKGROUND

Angina without angiographic evidence of obstructive coronary artery disease (ANOCA) is a highly prevalent condition with insufficient pathophysiological knowledge and lack of evidence-based medical therapies. This affects ANOCA patients prognosis, their healthcare utilization and quality of life. In current guidelines, performing a coronary function test (CFT) is recommended to identify a specific vasomotor dysfunction endotype. The NetherLands registry of invasive Coronary vasomotor Function testing (NL-CFT) has been designed to collect data on ANOCA patients undergoing CFT in the Netherlands.

METHODS

The NL-CFT is a web-based, prospective, observational registry including all consecutive ANOCA patients undergoing clinically indicated CFT in participating centers throughout the Netherlands. Data on medical history, procedural data and (patient reported) outcomes are gathered. The implementation of a common CFT protocol in all participating hospitals promotes an equal diagnostic strategy and ensures representation of the entire ANOCA population. A CFT is performed after ruling out obstructive coronary artery disease. It comprises of both acetylcholine vasoreactivity testing as well as bolus thermodilution assessment of microvascular function. Optionally, continuous thermodilution or Doppler flow measurements can be performed. Participating centers can perform research using own data, or pooled data will be made available upon specific request via a secure digital research environment, after approval of a steering committee.

CONCLUSION

NL-CFT will be an important registry by enabling both observational and registry based (randomized) clinical trials in ANOCA patients undergoing CFT.

Relationship between Inflammation and Vasospastic Angina

Coronary artery spasm (CAS) is a dynamic coronary stenosis causing vasospastic angina (VSA). However, VSA is a potentially lethal medical condition with multiple presentations, including sudden cardiac death. Despite investigations to explore its pathogenesis, no single mechanism has been found to explain the entire process of VSA occurrence. The roles of elevated local and systemic inflammation have been increasingly recognized in VSA. Treatment strategies to decrease local and systemic inflammation deserve further investigation.