Coronary Microvascular Vasodilatory Function: Related Clinical Features and Differences According to the Different Coronary Arteries and Types of Coronary Spasm

Evaluation of right ventricular pacing-induced coronary microvascular dysfunction using guide wire-based sensor technology: a case report

Background

The diagnosis of ischaemic non-obstructive coronary artery disease is crucial for the differential diagnosis of chest pain. However, the pathophysiology of chest pain and evaluation of coronary microcirculation in patients with right ventricular pacing (RVP) have not been sufficiently reported.

Case summary

The patient was a 53-year-old woman who underwent dual-chamber pacemaker implantation because of sinus node dysfunction. She experienced chest pain before pacemaker implantation; however, the frequency and severity of her chest pain increased after the implantation. She was referred for the evaluation of coronary microvascular dysfunction (CMD). Coronary angiography revealed no significant stenosis of the epicardial vessels. Subsequent evaluation of CMD showed that while the index of microcirculatory resistance [normalized index of microcirculatory resistance (IMR)] in the left anterior descending artery (LAD) was 19 U during the native rhythm, an increase in IMR (normalized IMR: 27 U) was observed during RVP.

Discussion

Right ventricular pacing may not only induce left ventricular dyssynchrony due to non-physiological excitation propagation but may also provoke CMD in the LAD territory, particularly in the septal branches, which could contribute to pacing-induced structural CMD and chest pain. However, RVP may well be a contributing but not exclusively a factor of CMD.

MINOCA: A Pathophysiological Approach of Diagnosis and Treatment-A Narrative Review

Myocardial infarction with non-obstructive coronary arteries (MINOCA) is a clinical entity characterized by the absence of significant coronary artery obstruction in epicardial arteries (<50%) on coronary angiography in the setting of acute myocardial infarction (AMI). This article aims to provide a narrative review of the pathophysiological mechanisms, diagnostic challenges, and prognosis associated with MINOCA based on pathophysiology regarding the atherosclerotic and non-atherosclerotic causes. Etiological factors, including thromboembolism, coronary artery spasm, spontaneous coronary artery dissection, coronary microvascular disease, and supply-demand mismatch, are addressed. Imaging modalities such as echocardiography, advances in coronary angiography like intravascular ultrasound (IVUS) and optical coherence tomography (OCT), cardiac magnetic resonance (CMR), and coronary computed tomography angiography (CCTA) are also analyzed. MINOCA patients have a better short-term prognosis compared to those with obstructive coronary artery disease but face significant long-term risks, underscoring the need for precise diagnosis and management strategies. Elevated inflammatory markers and specific genetic predispositions are also associated with adverse outcomes in MINOCA. This review focused on MINOCA from a pathophysiological perspective on the diverse underlying mechanisms, the challenges in achieving accurate diagnosis, the importance of a tailored therapeutic approach and the necessity for further investigation of clinical outcomes.

Factors Contributing to Coronary Microvascular Dysfunction in Patients with Angina and Non-Obstructive Coronary Artery Disease

BACKGROUND

Coronary microvascular dysfunction (CMD), characterised by a reduced coronary flow reserve (CFR) or an increased index of microcirculatory resistance (IMR), has received considerable attention as a cause of chest pain in recent years. However, the risks and causes of CMD remain unclear; therefore, effective treatment strategies have not yet been established. Heart failure or coronary artery disease (CAD) is a risk factor for CMD, with a higher prevalence among women. However, the other contributing factors remain unclear. In this study, we assessed the risk in patients with angina and non-obstructive coronary artery disease (ANOCA), excluding those with heart failure or organic stenosis of the coronary arteries. Furthermore, we analysed whether the risk of CMD differed according to component factors and sex.

METHODS

This study included 84 patients with ANOCA (36 men and 48 women; mean age, 63 years) who underwent coronary angiography and functional testing (CFT). The CFT included a spasm provocation test (SPT), followed by a coronary microvascular function test (CMVF). In the SPT, patients were mainly provoked by acetylcholine (ACh), and coronary spasm was defined as >90% transient coronary artery constriction on coronary angiography, accompanied by chest pain or ischaemic changes on electrocardiography. In 15 patients (18%) with negative ACh provocation, ergonovine maleate (EM) was administered as an additional provocative drug. In the CMVF, a pressure wire was inserted into the left anterior descending coronary artery using intravenous adenosine triphosphate, and the CFR and IMR were measured using previously described methods. A CFR < 2.0 or IMR ≥ 25 was indicative of CMD. The correlations between various laboratory indices and CMD and its components were investigated, and logistic regression analysis was performed, focusing on factors where p < 0.05.

RESULTS

Of the 84 patients, a CFR < 2.0 was found in 22 (26%) and an IMR ≥ 25 in 40 (48%) patients, with CMD identified in 46 (55%) patients. CMD was correlated with smoking (p = 0.020) and the use of EM (p = 0.020). The factors that correlated with a CFR < 2.0 included the echocardiograph index E/e' (p = 0.013), which showed a weak but positive correlation with the CFR (r = 0.268, p = 0.013). Conversely, the factors correlated with an IMR ≥ 25 included RAS inhibitor usage (p = 0.018) and smoking (p = 0.042). Assessment of the risk of CMD according to sex revealed that smoking (p = 0.036) was the only factor associated with CMD in men, whereas the left ventricular mass index (p = 0.010) and low glycated haemoglobin levels (p = 0.012) were associated with CMD in women.

CONCLUSIONS

Our results indicated that smoking status and EM use were associated with CMD. The risk of CMD differed between the two CMD components and sex. Although these factors should be considered when treating CMD, smoking cessation remains important. In addition, CMD assessment should be performed carefully when EM is used after ACh provocation. Further validation of our findings using prospective studies and large registries is warranted.

Acute Heart Failure Due to Multi-vessel Coronary Spasm

A 46-year-old man presented to our hospital with chest pain followed by coughing and dyspnea. His myocardial enzyme levels were almost normal, and electrocardiography and echocardiography showed no obvious abnormalities. Chest radiography revealed congestion. He was diagnosed with heart failure with a preserved ejection fraction (HFpEF). Although subjective symptoms improved with intravenous diuretics, the patient was admitted to the hospital for a close examination. Coronary angiography showed no obvious stenosis, and a subsequent spasm provocation test demonstrated the presence of multi-vessel and diffuse spasms. Coronary spasm should be considered as a differential cause of heart failure, even in patients with HFpEF.

Illness Perception and the Impact of a Definitive Diagnosis on Women With Ischemia and No Obstructive Coronary Artery Disease: A Qualitative Study

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) disproportionately impacts women, yet the underlying pathologies are often not distinguished, contributing to adverse health care experiences and poor quality of life. Coronary function testing at the time of invasive coronary angiography allows for improved diagnostic accuracy. Despite increased recognition of INOCA and expanding access to testing, data lack on first-person perspectives and the impact of receiving a diagnosis in women with INOCA.

METHODS

From 2020 to 2021, we conducted structured telephone interviews with 2 groups of women with INOCA who underwent invasive coronary angiography (n=29) at Yale New Haven Hospital, New Haven, CT: 1 group underwent coronary function testing (n=20, of whom 18 received a mechanism-based diagnosis) and the other group who did not undergo coronary function testing (n=9). The interviews were analyzed using the constant comparison method by a multidisciplinary team.

RESULTS

The mean age was 59.7 years, and 79% and 3% were non-Hispanic White and non-Hispanic Black, respectively. Through iterative coding, 4 themes emerged and were further separated into subthemes that highlight disease experience aspects to be addressed in patient care: (1) distress from symptoms of uncertain cause: symptom constellation, struggle for sensemaking, emotional toll, threat to personal and professional identity; (2) a long journey to reach a definitive diagnosis: self-advocacy and fortitude, healthcare interactions brought about further uncertainty and trauma, therapeutic alliance, sources of information; (3) establishing a diagnosis enabled a path forward: relief and validation, empowerment; and (4) commitment to promoting awareness and supporting other women: recognition of sex and racial/ethnic disparities, support for other women.

CONCLUSIONS

Insights about how women experience the symptoms of INOCA and their interactions with clinicians and the healthcare system hold powerful lessons for more patient-centered care. A coronary function testing-informed diagnosis greatly influences the healthcare experiences, quality of life, and emotional states of women with INOCA.

Frequency and Clinical Impact of Family History of Coronary Artery Disease in Patients with Vasospastic Angina

BACKGROUND

Family history (FH) of coronary artery disease (CAD) [FH-CAD] is a well-known risk factor for atherosclerotic CAD. However, FH-CAD frequency in patients with vasospastic angina (VSA) remains unknown, and the clinical characteristics and prognosis of VSA patients with FH-CAD are unclear. Therefore, this study compared FH-CAD frequency between patients with atherosclerotic CAD and those with VSA and examined the clinical characteristics and prognosis of VSA patients with FH-CAD.

METHODS

Coronary angiography and spasm provocation tests (SPT) were used to investigate chest pain of coronary artery origin in patients classified into atherosclerotic CAD (362 cases), VSA (221 cases; positive for SPT) and non-VSA (73 cases; negative for SPT) groups, with FH-CAD being defined. In the VSA group, flow-mediated vasodilation (FMD) and nitroglycerin-independent vasodilation (NID) via brachial artery echocardiography and clinical symptoms in the groups with and without FH-CAD were checked, with Kaplan-Meier curves revealing major adverse cardiovascular events (cardiac death and rehospitalisation for cardiovascular disease) between the two groups.

RESULTS

The atherosclerotic CAD group had a significantly lower FH-CAD frequency (12%, p = 0.029) than the VSA (19%) and non-VSA groups (19%). FH-CAD was more common in females in the VSA and non-VSA groups than in the atherosclerotic CAD group (p < 0.001). Nonpharmacological treatment for CAD in FH-CAD was more common in the atherosclerotic CAD group (p = 0.017). In the VSA group, FH-CAD tended to be more common in females (p = 0.052). Although no differences in FMD of the brachial artery were observed between the groups, the FH-CAD (+) group had significantly higher NID than the FH-CAD (-) group (p = 0.023). Kaplan-Meier's analysis revealed a similar prognosis between the two groups, and other clinical characteristics did not differ.

CONCLUSION

Patients with VSA have a higher FH-CAD frequency than those with atherosclerotic CAD, especially in females. Although FH-CAD may affect vascular function in patients with VSA, its effect on the severity and prognosis of VSA appears to be minimal. FH-CAD and its confirmation may assist in CAD diagnosis, especially in female patients.

Vasospastic angina in women: Clinical backgrounds and prognoses of patients younger than and older than 60 years

BACKGROUND

We frequently encounter cases of women with vasospastic angina (VSA). Additionally, some women with VSA are younger than 60 years old. However, it is unknown whether the characteristics of VSA in women aged < 60 years are different from those in women aged ≥ 60 years.

AIM

To investigate and compare the clinical characteristics and prognosis of VSA in women aged < 60 years from those in women aged ≥ 60 years.

METHODS

We enrolled 94 women with VSA who were diagnosed using the spasm provocation test. According to the age at diagnosis, the patients were divided into two groups: Group Y (age < 60 years, n = 17) and Group O (age ≥ 60 years, n = 77). Flow-mediated dilation (FMD) and nitroglycerin (NTG)-induced dilation (NID) of the brachial artery were performed and assessed using brachial ultrasonography. Moreover, conventional coronary risk factors, such as atherosclerotic lesions (stenosis > 20%) detected using coronary angiography and focal spasms (coronary spasm within one segment of one coronary artery), and major cardiovascular adverse events (MACE) were assessed in both groups.

RESULTS

Smoking was more prevalent in Group Y than in Group O (P = 0.04). FMD was similar in both groups (Group O: 4.3% ± 3.2%, Group Y: 4.5% ± 3.3%; P = 0.75), whereas NID was higher in Group Y (20.5% ± 8.6%) than in Group O (13.6% ± 5.3%, P < 0.01). Atherosclerosis was not detected in Group Y but was detected in Group O (61%, P < 0.01). Focal spasms were less frequent in Group Y (12%) than in Group O (38%, P = 0.04). The incidence of major adverse cardiac events did not differ between the two groups (P = 0.40).

CONCLUSION

Women aged < 60 years with VSA have less atherosclerotic lesions and focal spasms. These characteristics may be affected by smoking habits and vascular smooth muscle dysfunction.

Japanese Herbal Medicine (Kampo) as a Possible Treatment for Ischemia With Non-obstructive Coronary Artery Disease

Patients presenting with the syndrome of symptoms and signs suggesting ischemic heart disease but found to have no obstructed coronary arteries (INOCA) are increasingly recognized. Although there are non-invasive tests for the diagnosis of INOCA, such as transthoracic Doppler echocardiography, positron emission tomography, and cardiac magnetic resonance imaging to evaluate increased blood flow with adenosine and other agents, the diagnosis of INOCA by coronary angiography with the coronary spasm provocation test and coronary microvascular function evaluation using pressure wires has become the gold standard, but it is not well established in the treatment of INOCA. Despite the lack of objection to lifestyle modification and the use of coronary dilators, mainly calcium-channel blockers, for conditions involving epicardial coronary artery spasm, there is no entirely effective long-term treatment for microvascular spasm or coronary microvascular dysfunction. Although some combinations of drugs have been empirically administered in certain cases, it is difficult to conclude that they are sufficiently effective. Recently, it has been reported that some Japanese herbal medicines (Kampo) have been effective in the treatment of INOCA. In order to increase the knowledge on the treatment of INOCA, this review focuses on the effects of Japanese herbal medicine on INOCA and its presumed mechanisms and problems.

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.

Does the intracoronary pressure differ according to two types (diffuse or focal) of coronary spasm?

BACKGROUND

Several reports show that two types of coronary vasospasm (diffuse and focal spasm) are associated with the severity or prognosis of coronary spasm in patients with vasospastic angina (VSA). It is unclear whether intracoronary pressure differs between the two spasm types.

AIM

To investigate such relationships using a pressure wire during the spasm provocation test (SPT) in patients with VSA.

METHODS

Eighty-seven patients with VSA (average age: 67 years; 50 men, 37 women) underwent SPT. During the SPT, a pressure wire was advanced into the distal portion of the right coronary artery and left anterior descending coronary artery, and the ratio of the intracoronary pressure to the aortic pressure (Pd/Pa) was continuously monitored. An SPT was performed using acetylcholine (ACh), and the presence of coronary spasm was defined as the presence of > 90% arterial narrowing in response to an ACh infusion, with the usual chest symptoms and/or ischemic ECG changes. Focal spasm was defined as total or subtotal spasm within one segment of the AHA classification, while diffuse spasm was defined as > 90% spasm with two or more segments.

RESULTS

Among 87 patients, the frequencies of metabolic syndrome and having coronary atherosclerosis were higher in the focal group (n = 33) than in the diffuse spasm group (n = 54, P < 0.05). In the vessel analyses, in these 134 spastic segments, diffuse and focal spasms were detected in 100 and 34 vessels, respectively. The Pd/Pa at baseline was similar in both groups (diffuse: 0.96 ± 0.05, focal: 0.95 ± 0.05, P = 0.35); however, the Pd/Pa during coronary spasm was lower in focal spastic vessels (0.66 ± 0.20) than in diffuse spastic vessels (0.76 ± 0.11, P < 0.01), and the reduction in Pd/Pa during an SPT was also lower in focal spastic vessels (-0.29 ± 0.20) than in diffuse spastic vessels (-0.18 ± 0.11, P < 0.01). The presence of focal spasm was a significant factor responsible for reduction in Pd/Pa during SPT.

CONCLUSION

These findings suggest that focal spasm may be more severe than diffuse spasm, judging from the intracoronary pressure during coronary spasm.

Clinical Characteristics and Prognosis of Patients with Vasospastic Angina Subjected to the Spasm Provocation Test and the Unavoidable Use of Nitroglycerin

Background: Multi-vessel spasm (MVS) has a prognostic impact in patients with vasospastic angina (VSA). Thus, the presence of coronary spasm in both the left coronary artery (LCA) and right coronary artery (RCA) should be assessed through the spasm provocation test (SPT). Nitroglycerin (NTG) is used to avoid SPT-related complications; however, this unavoidable use of NTG may decrease the detection of MVS. Therefore, we investigated the frequency of the unavoidable use of NTG during SPT and clarified the clinical characteristics in patients with VSA who underwent the unavoidable use of NTG during STP. Methods: A total of 141 patients with positive SPT were evaluated. A positive SPT was defined as > 90% constriction in epicardial coronary arteries in response to acetylcholine, accompanied by the usual chest symptoms and/or ischaemic ST-T changes on electrocardiography. When a coronary spasm occurred, we usually wait for the spontaneous relief of the coronary spasm. However, if a prolonged coronary spasm or unstable haemodynamics occurred, 0.3 mg NTG was administered intracoronarily to promptly relieve the coronary spasm and this was defined as the unavoidable use of NTG. Even when the unavoidable use of NTG was administered in one coronary artery, an additional SPT was performed on another coronary artery. If a coronary spasm occurred in another coronary artery, a positive SPT was diagnosed. In contrast, if a coronary spasm was not induced after the unavoidable use of NTG, the judgement was classified as undiagnosed. The patients were divided into two groups according to the unavoidable use of NTG: U-NTG (n = 42) and the final use of NTG: F-NTG (n = 99). The clinical characteristics and frequencies of MVS (≥2 major coronary arteries in which a coronary spasm was provoked) and complications (malignant arrhythmia and unstable haemodynamics requiring catecholamines) during the SPT were compared between the groups. Results: Except for smoking status, all other clinical characteristics did not differ significantly between the groups. More current smokers were observed in the U-NTG group (29%) than in the F-NTG group (12%, p = 0.02). The frequency of MVS did not vary significantly between the groups (p = 0.28), with 64% for U-NTG and 55% for F-NTG. No significant difference was found between the groups in the frequency of severe complications during SPT (p = 0.83), with 2% for U-NTG and 3% for F-NTG. In the U-NTG group, the positive induction rate of coronary spasm in another coronary artery was 40% (17/42). Conclusions: The unavoidable use of NTG occurred in ~30% of patients with VSA, most of whom were current smokers. It did not decrease the detection of MVS and potentially prevented severe complications during SPT. Therefore, the unavoidable use of NTG is acceptable during SPT. However, an additional test may need to be performed to assess the presence of MVS.

The Impact of Myocardial Bridging on the Coronary Functional Test in Patients with Ischaemia with Non-Obstructive Coronary Artery Disease

Background: The possibility of myocardial bridging (MB) causing chest pain has been widely reported; however, the effect of MB on coronary microvessels has not been thoroughly investigated. Therefore, this study evaluated the effects of MB on epicardial coronary artery and coronary microvascular function during coronary angiography (CAG) and coronary function test (CFT) in patients with ischaemia with non-obstructive coronary artery disease (INOCA). Methods: This study included 62 patients with INOCA who underwent CAG and CFT for the left anterior descending coronary artery (LAD) to evaluate chest pain. In the CFT, acetylcholine was first administered intracoronarily in a stepwise manner, followed by chest symptoms, electrocardiographic ST-T changes and CAG. Positive coronary spasm was defined as coronary vasoconstriction of >90% on CAG accompanied by chest symptoms or electrocardiographic ST-T changes. After nitroglycerin administration, CAG was performed to assess MB, which was defined as systolic narrowing of the coronary artery diameter by >20% compared with that in diastole. Coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) were subsequently obtained via transvenous adenosine triphosphate infusion using a pressure wire. Coronary microvascular vasodilatory dysfunction (CMD) was defined as a CFR of <2.0 or an IMR of ≥25 units. Results: Of the 62 patients, 15 (24%) had MB. The patients’ characteristics did not differ between the two groups. Regarding the CAG and CFT results, the presence of coronary spasm in the LAD was higher in the MB (+) group (87%) than in the MB (−) group (53%, p = 0.02), whereas the values of CFR (MB (+): 2.7 ± 1.4, MB (−): 2.8 ± 1.1) and IMR (MB (+): 26.9 ± 1.0, MB (−): 30.0 ± 17.3) and the presence of CMD (MB (+): 53%, MB (−): 60%) were similar in the two groups. Conclusions: The findings suggest that MB predisposes patients with INOCA to coronary spasms. Conversely, MBs may have a limited effect on microvessels, particularly in such patients.

What More Can Be Delivered to Future Patients with Coronary Syndromes?

Coronary artery disease (CAD) is a major cardiovascular disease that imposes substantial clinical and socioeconomic burdens worldwide [...]