MINOCA Associated with a Myocardial Bridge: Pathogenesis, Diagnosis and Treatment

Coronary Artery Spasm: From Physiopathology to Diagnosis

Coronary artery spasm (CAS) is a reversible vasoconstriction of normal or atherosclerotic epicardial coronary arteries with a subsequent reduction in myocardial blood flow, leading to myocardial ischemia, myocardial infarction, severe arrhythmias, or even sudden death. It is an entity that should be recognized based on a particular clinical presentation. Numerous differences exist between CAS and obstructive coronary disease in terms of mechanisms, risk factors, and therapeutic solutions. The gold standard for CAS diagnosis is represented by transitory and reversible occlusion of the coronary arteries at spasm provocation test, which consists of an intracoronary administration of Ach, ergonovine, or methylergonovine during angiography. The pathophysiology of CAS is not fully understood. However, the core of CAS is represented by vascular smooth muscle cell contraction, with a circadian pattern. The initiating event of this contraction may be represented by endothelial dysfunction, inflammation, or autonomic nervous system unbalance. Our study explores the intricate balance of these factors and their clinical relevance in the management of CAS.

Morphological analysis of myocardial bridging leading to myocardial ischemia: myocardial coronary coupling

Introduction

Myocardial bridge (MB) is a segment of an otherwise extramyocardial blood vessel that traverses the myocardium. This congenital condition typically lacks obvious clinical manifestations during adolescence. However, as individuals age, the accumulated myocardial pressure on the coronary arteries can lead to non-obstructive coronary ischemia, angina pectoris, and even heart failure. Early diagnosis is crucial for assessing the risk of cardiovascular events.

Methods

This study performed a morphological analysis of MB in 75 patients using dual-source Computed Tomographic Angiography (CTA). Through geometric three-dimensional reconstruction, measurements and statistical analyses were conducted on muscle bridge length, depth, length-to-depth ratio, cross-sectional area, and coronary artery curvature.

Results

This study explores the morphological differences among normal individuals, those with superficial MB, and those with deep MB during diastole and systole under varying conditions of myocardial coronary coupling. The study found that the compression degree is greatest in the deep MB group, with the average compression level being approximately 17 times that of normal individuals and about 4.6 times that of patients with superficial MB.

Discussion

The differences in the average cross-sectional area are more significant than those in the minimum cross-sectional area. The depth of the MB is more closely related to the degree of compression, suggesting that clinical intervention and attention should be focused on deep MBs.

CT Predictors of Epicardial Coronary Spasm in Patients With Angina and Nonobstructive Coronary Arteries

BACKGROUND

Recent studies have shown that vasospastic angina (VSA) is associated with myocardial bridge (MB) and pericoronary adipose tissue inflammation. We aimed to investigate the clinical and coronary computed tomography angiographic (CCTA) features that could predict VSA in patients with angina and nonobstructive coronary arteries.

METHODS

We retrospectively studied patients with angina and nonobstructive coronary arteries who underwent a spasm provocation test and CCTA within 3 months before the spasm provocation test. Pericoronary adipose tissue inflammation was evaluated using the fat attenuation index (FAI) of the proximal reference diameter and the inner 2 mm adipose tissue layer (FAI2mm) from the vessel wall. Coronary plaques were qualitatively classified as noncalcified or calcified plaques in each vessel. In addition, MB was evaluated in the left anterior descending artery.

RESULTS

This study included 142 patients, with 55 (38.7%) diagnosed with VSA. Factors associated with VSA included male sex (74.5% versus 51.7%, P=0.01), smoking history (70.9% versus 52.9%, P=0.05), CCTA-defined MB (49.1% versus 28.7%, P=0.02), and FAI, especially FAI2mm in the right coronary artery-FAI2mm (-68.8 Hounsfield unit versus -74.0 Hounsfield unit, P<0.01), as well as the presence of CCTA-defined mixed or noncalcified plaque anywhere in the coronary tree (65.5% versus 39.1%, P<0.01). In a multivariable analysis, CCTA-defined MB (odds ratio, 2.23 [95% CI, 1.03-4.83]; P=0.04), right coronary artery-FAI2mm (odds ratio, 1.07 [95% CI, 1.02-1.12]; P<0.01), and the presence of mixed or noncalcified plaque (odds ratio, 3.15 [95% CI, 1.45-6.80]; P<0.01) were independently associated with VSA. A combination of CCTA-defined MB in the left descending artery, high right coronary artery-FAI2mm (≥-72.6 Hounsfield unit, median), and CCTA-defined mixed or noncalcified plaque in the coronary tree predicted VSA with a 75.0% probability, while the absence of all 3 factors precluded VSA with 95.6% probability.

CONCLUSIONS

For patients with angina and nonobstructive coronary arteries, a prespasm provocation test using a noninvasive comprehensive assessment with CCTA may help identify those at high risk for VSA.

Prognostic impact of coronary microvascular dysfunction assessed by AMR in acute coronary syndrome patients with chronic kidney disease

Background

Angiography-derived microcirculatory resistance (AMR) is proposed as a novel, pressure- temperature-wire-free and less-invasive method to evaluate coronary microvascular dysfunction (CMD). This study aims to examine the prognostic role of CMD assessed by AMR in predicting adverse events in acute coronary syndrome (ACS) patients with chronic kidney disease (CKD).

Methods

This retrospective cohort study included ACS with CKD patients in the China-Japan Friendship Hospital from January 2016 to November 2022. The patients were divided into CMD and non-CMD groups based on AMR values of less than or greater than 250 mmHg*s/m.

Results

A total of 345 eligible patients were included in this study. During a median follow-up of 23.0 months, higher prevalence rate of MACEs (28.3% vs. 15.1%, P = 0.003) and death (20.2% vs. 4.1%, P = 0.001) were observed in the CMD group. In multivariate Cox regression analysis, patients in the group of CMD had a 1.843 times higher hazard ratio (HR) for developing MACEs (HR: 1.843, 95% CI: 1.071-3.174, P = 0.027) and 5.325 times higher HR for developing death (HR: 5.325, 95% CI: 1.979-14.327, P < 0.001) for every 10 mmHg*s/m increment in AMR. The incorporation of AMR improved the predictive accuracy of the GRACE score for MACEs and death.

Conclusion

This study indicates that the AMR is significantly related to poor prognosis among patients with ACS and CKD. Furthermore, AMR could improve the predictive power of the GRACE risk score. These results indicated that AMR may serve as a valuable clinical tool for classification, risk stratification or therapy individualization in these patients.

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.

Myocardial infarction with non-obstructive coronary arteries in a young seropositive woman with human immunodeficiency virus: a case report and review of the literature

BACKGROUND

Elevated susceptibility to acute myocardial infarction and various cardiovascular diseases has been observed in individuals infected with the human immunodeficiency virus compared with the uninfected population, as demonstrated in numerous studies. The precise mechanism by which human immunodeficiency virus infection heightens the risk of acute myocardial infarction remains elusive. The manifestation of acute coronary syndrome in young patients with human immunodeficiency virus may deviate from the typical, displaying distinct pathophysiological and clinical characteristics. The occurrence of myocardial infarction with non-obstructive coronary arteries in young patients with human immunodeficiency virus poses diagnostic and treatment challenges.

CASE PRESENTATION

We present the case of a 46-year-old African woman with no traditional atherosclerotic risk factors. She was diagnosed with human immunodeficiency virus-1 infection 2 years prior to her current admission for chest pain. Her troponin levels were elevated, suggestive of acute coronary syndrome. Although coronary angiography ruled out coronary artery stenosis, it revealed mild myocardial bridging in the left anterior descending artery. Cardiac magnetic resonance imaging confirmed myocardial infarction, indicating a myocardial infarction with non-obstructive coronary arteries with an apical thrombus in the left ventricle. Following medical treatment, the patient experienced resolution of chest pain and improvement in ST-segment elevation.

CONCLUSIONS

In young female patients without traditional risk factors, human immunodeficiency virus infection is a possible etiological factor for myocardial infarction with non-obstructive coronary arteries. The likely pathophysiological pathway is superficial endothelial cell denudation as a result of chronic inflammation and immune activation.

Concurrent Myocardial Bridging and Coronary Artery Disease: A Study of an Iranian Population

Background

Myocardial bridging (MB) has been associated with acute coronary syndrome, ischemia, arrhythmia, and even sudden death. This study investigated the prevalence of MB and its complications and manifestations.

Methods

This cross-sectional study was conducted on symptomatic coronary patients who underwent angiography between March 2022 and March 2023 at Afshar or Shahid Sadoughi hospitals in Yazd, Iran. The angiographic reports of all patients were evaluated. Cases with MB were selected, and their angiographic films were assessed by an interventional cardiologist for diagnostic accuracy. Baseline, radiological, and clinical characteristics were also evaluated. Data were collected and analyzed using SPSS, version 20.0. The dependent variable was stratified based on independent variables using the χ2 test.

Results

Out of 3750 symptomatic patients, 165 (4.4%) were diagnosed with MB. Among these, 111 (67.3%) were male, and the mean age was 56.87±10.06 years. A total of 152 patients had MB in the left anterior descending artery, representing the highest occurrence proportion at 92.1%. The most common types of coronary artery disease (CAD) diagnosed included mono-vessel disease and slow flow, accounting for 35.1% and 25.8%, respectively. There was no significant frequency distribution of CAD co-occurrence based on baseline and radiological features (P>0.050).

Conclusion

This study provides valuable insights into the prevalence of MB in Iran and its co-occurrence with CAD. While some findings align with previous research, certain discrepancies warrant further investigation.

Coronary Spasm Testing with Acetylcholine: A Powerful Tool for a Personalized Therapy of Coronary Vasomotor Disorders

Coronary vasomotor disorders (CVD) are characterized by transient hypercontraction of coronary vascular smooth muscle cells, leading to hypercontraction of epicardial and/or microvascular coronary circulation. CVDs play a relevant role in the pathogenesis of ischemia, angina and myocardial infarction with non-obstructive coronary arteries. Invasive provocative testing with intracoronary Acetylcholine (ACh) administration is the gold standard tool for addressing CVD, providing relevant therapeutic and prognostic implications. However, safety concerns preclude the widespread incorporation of the ACh test into clinical practice. The purpose of this review is to shed light on the pathophysiology underlying CVD and on the clinical role of the ACh test, focusing on safety profile and prognostic implications. We will also discuss contemporary evidence on the management of CVD and the role of the ACh test in driving a personalized approach of patients with CVD.