Invasive evaluation of patients with angina in the absence of obstructive coronary artery disease

INOCA: Ischemia in non-obstructive coronary arteries

This article provides a summary of the clinical spectrum of no obstructive coronary arteries. We describe the pathologies, invasive and noninvasive assessment, and management strategies.

Nonobstructive epicardial coronary artery disease: an evolving concept in need of diagnostic and therapeutic guidance

For decades, we have been treating patients presenting with angina and concerning electrocardiographic changes indicative of ischemia or injury, in whom no culprit epicardial coronary stenosis was found during diagnostic coronary angiography. Unfortunately, the clinical outcomes of these patients were not better than those with recognized obstructive coronary disease. Improvements in technology have allowed us to better characterize these patients. Consequently, an increasing number of patients with ischemia and no obstructive coronary artery disease (INOCA) or myocardial infarction in the absence of coronary artery disease (MINOCA) have now gained formal recognition and are more commonly encountered in clinical practice. Although both entities might share functional similarities at their core, they pose significant diagnostic and therapeutic challenges. Unless we become more proficient in identifying these patients, particularly those at higher risk, morbidity and mortality outcomes will not improve. Though this field remains in constant flux, data continue to become available. Therefore, we thought it would be useful to highlight important milestones that have been recognized so we can all learn about these clinical entities. Despite all the progress made regarding INOCA and MINOCA, many important knowledge gaps continue to exist. For the time being, prompt identification and early diagnosis remain crucial in managing these patients. Even though we are still not clear whether intensive medical therapy alters clinical outcomes, we remain vigilant and wait for more data.

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.

The Relationship between the Systemic Immune-Inflammation Index and Ischemia with Non-Obstructive Coronary Arteries in Patients Undergoing Coronary Angiography

BACKGROUND

Ischemia with the non-obstructive coronary artery (INOCA) is an ischemic heart disease that mostly includes coronary microvascular dysfunction and/or epicardial coronary vasospasm due to underlying coronary vascular dysfunction and can be seen more commonly in female patients. The systemic immune-inflammation index (SII, platelet × neutrophil/lymphocyte ratio) is a new marker that predicts adverse clinical outcomes in coronary artery disease (CAD).

OBJECTIVE

This study aims to investigate the relationship between INOCA and SII, a new marker associated with inflammation.

METHODS

A total of 424 patients (212 patients with INOCA and 212 normal controls) were included in the study. Peripheral venous blood samples were received from the entire study population prior to coronary angiography to measure SII and other hematological parameters. In our study, the value of p<0.05' was considered statistically significant.

RESULTS

The optimal cut-off value of SII for predicting INOCA was 153.8 with a sensitivity of 44.8% and a specificity of 78.77% (Area under the curve [AUC]: 0.651 [95% CI: 0.603-0.696, p=0.0265]). Their ROC curves were compared to assess whether SII had an additional predictive value over components. The AUC value of SII was found to be significantly higher than that of lymphocyte (AUC: 0.607 [95% CI: 0.559-0.654, p = 0.0273]), neutrophil (AUC: 0.559 [95%CI: 0.511-0.607, p=0.028]) and platelet (AUC: 0.590 [95% CI: 0.541-0.637, p = 0.0276]) in INOCA patients.

CONCLUSIONS

A high SII level was found to be independently associated with the existence of INOCA. The SII value can be used as an indicator to add to the traditional expensive methods commonly used in INOCA prediction.

Coronary slow flow and angiography-derived index of microcirculatory resistance as prognostic predictors in patients with angina and normal coronary arteries: a retrospective cohort study

BACKGROUND

This study aims to investigate prognostic implications of coronary slow flow (CSF) and angiography-derived index of microcirculatory resistance (caIMR) in patients with angina and normal coronary arteries.

METHODS

A total of 582 patients were enrolled with angiographically normal coronary arteries. caIMR was calculated using a commercial software. Patients were followed up for a median of 45 months. The primary endpoint was defined as major adverse cardiovascular events (MACEs) comprising death, myocardial infarction and readmission for angina or heart failure.

RESULTS

CSF was diagnosed when TIMI grade 2 flow presented in at least one coronary artery. Multivariate analysis indicated TIMI-flow-based determination of CSF was not significantly associated with MACEs [hazard ratio (HR): 2.14; 95% confidence interval (CI): 0.87-5.31; p = 0.099), while caIMR >42 (HR: 2.53; 95% CI: 1.02-6.32; p = 0.047) were independent predictors of MACEs. Incorporation of caIMR improved the area under the curve from 0.587 to 0.642.

CONCLUSIONS

caIMR was an independent prognostic factor of long-term cardiovascular events in patients with CSF. Evaluation of caIMR improved the risk stratification of patients with angiographically-normal coronary arteries.

Implementation of Microcirculation Examination in Clinical Practice-Insights from the Nationwide POL-MKW Registry

Background and Objectives: The assessment of coronary microcirculation may facilitate risk stratification and treatment adjustment. The aim of this study was to evaluate patients' clinical presentation and treatment following coronary microcirculation assessment, as well as factors associated with an abnormal coronary flow reserve (CFR) and index of microcirculatory resistance (IMR) values. Materials and Results: This retrospective analysis included 223 patients gathered from the national registry of invasive coronary microvascular testing collected between 2018 and 2023. Results: The frequency of coronary microcirculatory assessments in Poland has steadily increased since 2018. Patients with impaired IMR (≥25) were less burdened with comorbidities. Patients with normal IMR underwent revascularisation attempts more frequently (11.9% vs. 29.8%, p = 0.003). After microcirculation testing, calcium channel blockers (CCBs) and angiotensin-converting enzyme inhibitors were added more often for patients with IMR and CFR abnormalities, respectively, as compared to control groups. Moreover, patients with coronary microvascular dysfunction (CMD, defined as CFR and/or IMR abnormality), regardless of treatment choice following microcirculation assessment, were provided with trimetazidine (23.2%) and dihydropyridine CCBs (26.4%) more frequently than those without CMD who were treated conservatively (6.8%) and by revascularisation (4.2% with p = 0.002 and 0% with p < 0.001, respectively). Multivariable analysis revealed no association between angina symptoms and IMR or CFR impairment. Conclusions: The frequency of coronary microcirculatory assessments in Poland has steadily increased. Angina symptoms were not associated with either IMR or CFR impairment. After microcirculation assessment, patients with impaired microcirculation, expressed as either low CFR, high IMR or both, received additional pharmacotherapy treatment more often.

Beyond Coronary Artery Disease: Assessing the Microcirculation

Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary arteries, nearly half of patients with stable angina and IHD who undergo invasive coronary angiography do not have obstructive epicardial coronary artery disease. Ischemia with nonobstructive coronary arteries is frequently caused by microvascular angina with underlying coronary microvascular dysfunction (CMD). Greater understanding the pathophysiology, diagnosis, and treatment of CMD holds promise to improve clinical outcomes of patients with ischemic heart disease.

13N-ammonia positron emission tomography for diagnosis and monitoring of ischemia without obstructive coronary artery disease

BACKGROUND

Ischemia with no obstructive coronary arteries (INOCA), a chronic disorder with a poor prognosis, remains challenging to diagnose. 13N-ammonia positron emission tomography (13NH3 PET), which can quantify microcirculation, is its most reliable detection method. We aimed to investigate the differences in 13NH3 PET findings between INOCA and coronary artery disease (CAD).

METHODS

Overall, consecutive 433 patients with known or suspected CAD underwent adenosine-stress 13NH3 PET. Based on the European Society of Cardiology guidelines, INOCA was defined as typical angina without coronary stenosis (INOCA n = 45, CAD n = 293, no CAD n = 95). Papillary muscle ischemia (PMI) and global myocardial flow reserve (MFR) were examined as microvascular injuries using 13NH3 PET.

RESULTS

PMI was observed significantly more frequently in patients with INOCA than in those with CAD (40.0% vs. 11.6%, respectively; p = 0.02). Global MFR (1.84 ± 0.54 vs. 2.08 ± 0.66, respectively; p < 0.0001) and reactive hyperemia index were significantly lower in patients with INOCA than in those with CAD. Forty-five major adverse cardiac events (MACE) were recorded in a median follow-up time of 827 days. Kaplan-Meier analysis revealed that the survival rate worsened in patients with INOCA and PMI (log-rank test, p = 0.001). In the Cox proportional hazards model, PMI was an independent predictive factor for MACE (odds ratio, 4.16; 95% confidence interval, 2.13-8.15; p < 0.0001).

CONCLUSIONS

PMI presence and decreased MFR were 13NH3 PET findings characteristic of INOCA. 13NH3 PET can be used to monitor the treatment course.

Clinical aspects of ischemia with no obstructive coronary artery disease (INOCA)

Ischemia with no obstructive coronary arteries (INOCA) is defined as patients with evidence of myocardial ischemia without obstructive coronary artery disease. About 3-4 million people in the United States have INOCA, more commonly affecting women, and carries adverse morbidity, mortality, and relatively high healthcare costs. The pathophysiology of INOCA appears to be multi-factorial with a variety of contributing mechanisms. Diagnosis of INOCA is suggested by non-invasive or invasive testing consistent with myocardial ischemia. Due to the high prevalence of coronary risk factors and atherosclerosis in the INOCA population, current treatment strategies target angina, coronary atherosclerosis, and atherosclerotic risk factors, as well as burgeoning treatment of coronary microvascular dysfunction (CMD). Ongoing clinical trials are assessing different options.

Vasospastic angina: a review on diagnostic approach and management

Vasospastic angina (VSA) refers to chest pain experienced as a consequence of myocardial ischaemia caused by epicardial coronary spasm, a sudden narrowing of the vessels responsible for an inadequate supply of blood and oxygen. Coronary artery spasm is a heterogeneous phenomenon that can occur in patients with non-obstructive coronary arteries and obstructive coronary artery disease, with transient spasm causing chest pain and persistent spasm potentially leading to acute myocardial infarction (MI). VSA was originally described as Prinzmetal angina or variant angina, classically presenting at rest, unlike most cases of angina (though in some patients, vasospasm may be triggered by exertion, emotional, mental or physical stress), and associated with transient electrocardiographic changes (transient ST-segment elevation, depression and/or T-wave changes). Ischaemia with non-obstructive coronary arteries (INOCA) is not a benign condition, as patients are at elevated risk of cardiovascular events including acute coronary syndrome, hospitalization due to heart failure, stroke and repeat cardiovascular procedures. INOCA patients also experience impaired quality of life and associated increased healthcare costs. VSA, an endotype of INOCA, is associated with major adverse events, including sudden cardiac death, acute MI and syncope, necessitating the study of the most effective treatment options currently available. The present literature review aims to summarize current data relating to the diagnosis and management of VSA and provide details on the sequence that treatment should follow.

Angiography-based coronary microvascular assessment with and without intracoronary pressure measurements: a systematic review

BACKGROUND

In recent years, several indices have been proposed for quantifying coronary microvascular resistance. We intended to conduct a comprehensive review that systematically evaluates indices of microvascular resistance derived from angiography.

OBJECTIVE

The objective of this study was to identify and analyze angiography-derived indices of microvascular resistance that have been validated against an invasive reference method. We aimed to compare their limits of agreement with their reference methods and explore their advantages and inherent limitations.

METHODS AND RESULTS

We searched PubMed from inception until 2022 for studies on different techniques for quantifying microvascular resistance. Seven studies met the inclusion criteria. Five studies included techniques that applied calculations based solely on invasive angiography, and were validated against invasively measured thermodilution-derived index of microvascular resistance. The remaining two studies combined angiography with invasively measured intracoronary pressure data, and were validated against invasive Doppler measurements. We converted the ± 1.96 standard deviation limits of agreement with the reference method from the seven studies into percentages relative to the cut-off value of the reference method. The lower limits of agreement for angiography-based methods ranged from - 122 to - 60%, while the upper limits ranged from 74 to 135%. The range of the limits of agreement was considerably lower for the two combined angiography- and pressure-based methods, standing at - 52 to 60% and - 25 to 27%.

CONCLUSION

Our findings suggest that combined angiography- and pressure-based methods provide a more reliable assessment of microvascular resistance compared to methods relying solely on angiography. Central illustration. Comparative assessment of image-based methods quantifying microvascular resistance with and without intracoronary pressure measurements. Angiography-based methods rely on angiography alone to calculate the microvascular resistance by utilizing angiographic frame counting to extrapolate coronary flow (Q) and subsequently deriving distal coronary pressure using fluid dynamic equations. Combined angiography- and pressure-based methods utilize invasive intracoronary pressure gradients measured during rest and maximal vasodilation to determine coronary flow in their calculation of microvascular resistance. The combined methods showed more acceptable levels of agreement with their reference methods compared to angiography-based methods alone.

Angina and Non-Obstructive Coronary Artery (ANOCA) Patients with Coronary Vasomotor Disorders

Angina and Non-Obstructive Coronary Artery (ANOCA) patients often lack a clear explanation for their symptoms, and are frequently discharged with the label of "unspecified chest pain", despite the availability of functional coronary angiography (provocative spasm and microvascular function testing) to identify potential underlying coronary vasomotor disorders. This study compared the outcomes of ANOCA patients with a coronary vasomotor disorder diagnosis post elective coronary angiography to patients discharged with unspecified chest pain. Using the CADOSA (Coronary Angiogram Database of South Australia) registry, consecutive symptomatic patients (n = 7555) from 2012 to 2018 underwent elective angiography; 30% had ANOCA (stenosis <50%). Of this cohort, 9% had documented coronary vasomotor disorders diagnosed, and 91% had unspecified chest pain. Patients with coronary vasomotor disorders were younger and had a similar female prevalence compared with those with unspecified chest pain. New prescriptions of calcium channel blockers and long-acting nitrates were more common for the coronary vasomotor cohort at discharge. In the 3 years following angiography, both groups had similar all-cause mortality rates. However, those with coronary vasomotor disorders had higher rates of emergency department visits for chest pain (39% vs. 15%, p < 0.001) and readmissions for chest pain (30% vs. 10%, p < 0.001) compared with those with unspecified chest pain. This real-world study emphasizes the importance of identifying high-risk ANOCA patients for personalized management to effectively address their symptoms.

Coronary microvascular dysfunction and myocardial infarction with non-obstructive coronary arteries: Where do we stand?

In the past decade, scientific and clinical research has provided a translational perspective on myocardial infarction (MI) with non-obstructive coronary arteries (MINOCA). MINOCA is characterized by clinical documentation of an acute MI but angiography shows no significant coronary artery obstruction (stenosis <50%). The prevalence of MINOCA is estimated to range from approximately 6 to 10% among MI patients, and those with this condition have a poor prognosis, experiencing high rates of mortality, rehospitalization, and socioeconomic burden. MINOCA represents a major unmet need in cardiovascular medicine, with uncertain clinical management. It is a complex condition that can be caused by various factors, including atherosclerosis, plaque rupture, coronary vasospasm, and microvascular dysfunction. Effective management of MINOCA depends on identifying the underlying mechanism of the infarction, thus a systematic diagnostic approach is recommended. Contemporary data shows that a significant number of patients exhibit structural and functional abnormalities in coronary microcirculation, which is referred to as coronary microvascular dysfunction (CMD). CMD plays a crucial role in patients with signs and symptoms of myocardial ischemia and non-obstructive coronary artery stenosis, including MINOCA. Furthermore, conducting a thorough evaluation of coronary function can have significant prognostic and therapeutic implications, since personalized patient management strategies based on this assessment have been shown to improve symptoms and prognosis. Therefore, an accurate and timely diagnosis of CMD is essential for effective patient management, which can be achieved through various invasive and non-invasive methods. This review will discuss the pathophysiological understanding, current diagnostic techniques, and management strategies of patients with MINOCA and CMD.

Invasive Coronary Assessment in Myocardial Ischemia with No Obstructive Coronary Arteries

PURPOSE OF REVIEW

The purpose of this review is threefold: (i) to give an overview of well-established invasive methods for assessing patients with ischemia with no obstructive coronary arteries (INOCA) in the cardiac catheterization laboratory; (ii) to describe the prognostic and treatment implications based on these findings, and (iii) to discuss current knowledge gaps and future perspectives.

RECENT FINDINGS

Recent studies have demonstrated that invasive coronary function testing not only allows for risk stratification of patients with INOCA but also guides medical therapy with improvement in symptoms and quality of life. Based on these findings, invasive coronary function assessment is now a class 2a recommendation in the 2021 ACC/AHA chest pain guideline to improve the diagnosis of coronary microvascular dysfunction and to enhance risk stratification. Invasive functional testing for patients with INOCA is well established and easily performed in the catheterization laboratory. Comprehensive invasive assessment is a key to differentiating INOCA endotypes and optimizing both medical therapy and preventive strategies including lifestyle modification.

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.

Challenge in Diagnosis and Management of a Patient With Myocardial Bridge and Coronary Artery Spasm

Positive ischemia by noninvasive imaging studies often results in nonobstructive disease in cardiac catheterization. In this case, we observed ischemia by nuclear stress test in only the anteroseptal area, and the apex is free of ischemia. Coronary angiogram findings were unremarkable, but intravascular ultrasound confirmed the long length of the myocardial bridge. Further testing with spasm provocation and microvascular testing showed diffuse epicardial spasm in this area of myocardial bridge without microvascular dysfunction. We observed the myocardial bridge but no microvascular dysfunction. This case illustrates the coexistence of spasm in the area of a myocardial bridge and the challenges in the medical management of these patients. (Level of Difficulty: Advanced.).

Echocardiographic assessment of primary microvascular angina and primary coronary microvascular dysfunction

There is an increasing interest in the role of echocardiography in the evaluation of primary microvascular angina, which is attributed to primary coronary microvascular dysfunction. Valid echocardiographic techniques are expected to facilitate the diagnosis and follow-up of these patients and would be valuable for research purposes and therapy evaluation. However, adequate echocardiographic data are lacking, and the interpretation of the limited available literature is hindered by the previous addition of microvascular angina under more inclusive entities, such as cardiac syndrome X. In experienced hands, the assessment of primary coronary microvascular dysfunction in patients with suspected primary microvascular angina, using multiple echocardiographic techniques is feasible, relatively inexpensive, and safe. Exclusion of obstructive epicardial coronary artery disease is, however, a prerequisite for diagnosis. Two-dimensional transthoracic echocardiography, routine stress echocardiography, and speckle-tracking echocardiography indirectly assess primary coronary microvascular dysfunction by evaluating potential impairment in myocardial function and lack diagnostic sensitivity and specificity. Conversely, certain echocardiographic techniques, including Doppler-derived coronary flow velocity reserve and myocardial contrast echocardiography, assess some coronary microvascular dysfunction parameters and have exhibited diagnostic and prognostic potentials. Doppler-derived coronary flow velocity reserve is the best studied and only guideline-approved echocardiographic technique for documenting coronary microvascular dysfunction in patients with suspected microvascular angina. Myocardial contrast echocardiography, by comparison, can detect heterogeneous and patchy myocardial involvement by coronary microvascular dysfunction, which is an advantage over the common practice of coronary flow velocity reserve assessment in a single vessel (commonly the left anterior descending artery) which only reflects regional microvascular function. However, there is no consensus regarding the diagnostic criteria, and expertise performing this technique is limited. Echocardiography remains underexplored and inadequately utilized in the setting of microvascular angina and coronary microvascular dysfunction. Appraisal of the current echocardiographic literature regarding coronary microvascular dysfunction and microvascular angina is important to stay current with the progress in its clinical recognition and create a basis for future research and technological advancements.

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.

Prognostic utility of 99mTc-MIBI single photon emission computerized tomography myocardial perfusion imaging in patients with ischemia and non-obstructive coronary artery disease

Objective

The aim of our study was to evaluate the prognostic value of gated SPECT MPI in non-obstructed coronary arteries (INOCA) patients, sought to stratify patients more accurately and thus derive more reliable prognostic information.

Materials and methods

In total, 167 patients with INOCA were enrolled. The patients were divided into two groups according to their SSS. Patients were followed-up regularly in terms of major adverse cardiovascular event (MACE), including cardiac death, nonfatal myocardial infarction, stroke, re-hospitalization with angina pectoris, and recurrent angina pectoris. Kaplan-Meier curves and Cox's proportional hazards models were used to analyze survival and identify predictive factors.

Results

Adverse cardiac events occurred in 33 cases (19.8%). The rate of MACE was higher in the summed stress score (SSS) ≥4 group than in the SSS 0-3 group (30.1% vs. 9.5%, respectively, P = 0.001) and MACE-free survival was lower (annual MACE-free rates of 87.5% vs. 96.2%, respectively, P = 0.003). Event-free survival was consistently higher in patients with normal arteries than in those with non-obstructive coronary artery disease (annual MACE-free rates of 96.1% and 88.4%, P = 0.035). When the SSS and the CAG results were combined, patients with normal coronary arteries (SSS 0-3) had the best prognosis and those with non-obstructive coronary artery stenosis (SSS ≥ 4) had the worst. However, the early prognosis of patients with non-obstructive coronary artery disease and SSS of 0-3 was comparable to that of patients with normal coronary arteries and SSS ≥ 4 (annual MACE-free rates of 100%, 94.6%, 93.1%, and 78.2%, respectively). Multivariate Cox's regression indicated that the SSS [hazard ratio (HR) = 1.126, 95% confidence interval (CI) 1.042-1.217, P = 0.003] and non-obstructive coronary artery disease (HR = 2.559, 95% CI 1.249-5.246, P = 0.01) were predictors of adverse cardiac events.

Conclusion

SPECT MPI data were prognostic for INOCA patients, thus identifying groups at high risk. The long-term predictive efficacy of such data exceeded that of CAG data. A combination of the two measures more accurately stratified INOCA patients in terms of risk.

The prognostic value of CZT SPECT myocardial blood flow (MBF) quantification in patients with ischemia and no obstructive coronary artery disease (INOCA): a pilot study

BACKGROUND

Despite the demonstrated adverse outcome, it is difficult to early identify the risks for patients with ischemia and no obstructive coronary artery disease (INOCA). We aimed to explore the prognostic potential of CZT SPECT in INOCA patients.

METHODS

The study population consisted of a retrospective cohort of 118 INOCA patients, all of whom underwent CZT SPECT imaging and invasive coronary angiography (ICA). Dynamic data were reconstructed, and MBF was quantified using net retention model. Major adverse cardiovascular events (MACEs) were defined as cardiovascular death, nonfatal myocardial infarction, nonfatal stroke, heart failure, late coronary revascularization, or hospitalization for unstable angina.

RESULTS

During a median follow-up of 15 months (interquartile range (IQR) 11-20), 19 (16.1%) MACEs occurred; both stress myocardial blood flow (sMBF) ([Formula: see text]) and coronary flow reserve (CFR) ([Formula: see text]) were significantly lower in the MACE group. Optimal thresholds of sMBF<3.16 and CFR<2.52 were extracted from the ROC curves, and both impaired sMBF (HR: 15.08; 95% CI 2.95-77.07; [Formula: see text]) and CFR (HR: 6.51; 95% CI 1.43-29.65; [Formula: see text]) were identified as prognostic factors for MACEs. Only sMBF<3.16 (HR: 11.20; 95% CI 2.04-61.41; [Formula: see text]) remained a robust predictor when sMBF and CFR were integrated considered. Compared with CFR, sMBF provides better prognostic model discrimination and reclassification ability (C-index improvement = 0.06, [Formula: see text]; net reclassification improvement (NRI) = 0.19; integrated discrimination improvement (IDI) = 0.10).

CONCLUSION

The preliminary results demonstrated that quantitative analysis on CZT SPECT provides prognostic value for INOCA patients, which may allow the stratification for early prevention and intervention.

Coronary Microvascular Disease in Contemporary Clinical Practice

Coronary microvascular disease (CMD) causes myocardial ischemia in a variety of clinical scenarios. Clinical practice guidelines support routine testing for CMD in patients with ischemia with nonobstructive coronary artery disease. Invasive testing to identify CMD requires Doppler or thermodilution measures of flow to determine the coronary flow reserve and measures of microvascular resistance. Acetylcholine coronary reactivity testing identifies concomitant endothelial dysfunction, microvascular spasm, or epicardial coronary spasm. Comprehensive testing may improve symptoms, quality of life, and patient satisfaction by establishing a diagnosis and guiding-targeted medical therapy and lifestyle measures. Beyond ischemia with nonobstructive coronary artery disease, testing for CMD may play a role in patients with acute myocardial infarction, angina following coronary revascularization, heart failure with preserved ejection fraction, Takotsubo syndrome, and after heart transplantation. Additional education and provider awareness of CMD and its role in cardiovascular disease is needed to improve patient-centered outcomes of ischemic heart disease.

Coronary Artery Spasm-Related Heart Failure Syndrome: Literature Review

Although heart failure (HF) is a clinical syndrome that becomes worse over time, certain cases can be reversed with appropriate treatments. While coronary artery spasm (CAS) is still underappreciated and may be misdiagnosed, ischemia due to coronary artery disease and CAS is becoming the single most frequent cause of HF worldwide. CAS could lead to syncope, HF, arrhythmias, and myocardial ischemic syndromes such as asymptomatic ischemia, rest and/or effort angina, myocardial infarction, and sudden death. Albeit the clinical significance of asymptomatic CAS has been undervalued, affected individuals compared with those with classic Heberden's angina pectoris are at higher risk of syncope, life-threatening arrhythmias, and sudden death. As a result, a prompt diagnosis implements appropriate treatment strategies, which have significant life-changing consequences to prevent CAS-related complications, such as HF. Although an accurate diagnosis depends mainly on coronary angiography and provocative testing, clinical characteristics may help decision-making. Because the majority of CAS-related HF (CASHF) patients present with less severe phenotypes than overt HF, it underscores the importance of understanding risk factors correlated with CAS to prevent the future burden of HF. This narrative literature review summarises and discusses separately the epidemiology, clinical features, pathophysiology, and management of patients with CASHF.

Clinical Implication and Optimal Management of Myocardial Bridging: Role of Cardiovascular Imaging

Myocardial bridging (MB) was historically considered a benign structure as most people with MB are clinically asymptomatic. Recently, however, mounting evidence indicates that MB can cause adverse cardiac events owing to arterial systolic compression/diastolic restriction, atherosclerotic plaque progression upstream from MB, and/or vasospastic angina. In MB patients with refractory angina, the optimal treatment strategy should be determined individually based on versatile anatomic and hemodynamical assessments that often require multidisciplinary diagnostic approaches. The present review summarizes the clinical implication and management of MB, highlighting the role of imaging modalities currently available in this arena.

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.

Coronary Microvascular Spasm: Clinical Presentation and Diagnosis

Professor Maseri pioneered the research and treatment of coronary vasomotion abnormalities represented by coronary vasospasm and coronary microvascular dysfunction (CMD). These mechanisms can cause myocardial ischaemia even in the absence of obstructive coronary artery disease, and have been appreciated as an important aetiology and therapeutic target with major clinical implications in patients with ischaemia with non-obstructive coronary artery disease (INOCA). Coronary microvascular spasm is one of the key mechanisms responsible for myocardial ischaemia in patients with INOCA. Comprehensive assessment of coronary vasomotor reactivity by invasive functional coronary angiography or interventional diagnostic procedure is recommended to identify the underlying mechanisms of myocardial ischaemia and to tailor the best treatment and management based on the endotype of INOCA. This review highlights the pioneering works of Professor Maseri and contemporary research on coronary vasospasm and CMD with reference to endothelial dysfunction, Rho-kinase activation and inflammation.

Clinical Value of Positron Emission Tomography Myocardial Perfusion Imaging and Blood Flow Quantification

Myocardial blood flow (MBF) and flow reserve (MFR) measurements by PET/computed tomography provide incremental diagnostic and prognostic information over traditional quantification of ischemia and scar by myocardial perfusion imaging. A normal stress MBF and MFR (>2.0) have a very high negative predictive value for excluding high-risk obstructive coronary artery disease (CAD). These flow measurements are also used for surveillance of coronary allograft vasculopathy after heart transplantation. A global normal MFR (>2.0) identifies patients at lower clinical risk, whereas a severely reduced MFR (<1.5) identifies patients at high risk for adverse events, even among patients without regional perfusion abnormalities.

A bibliometric analysis on the progress of myocardial bridge from 1980 to 2022

Introduction

Although the vast majority of patients with a myocardial bridge (MB) are asymptomatic, the anomaly was found to be associated with stable or unstable angina, vasospastic angina, acute coronary syndrome, and even malignant arrhythmias and sudden cardiac death in some cases.

Methods

By retrieving the relevant literature on MB from 1 January 1980 to 31 July 2022 from the Web of Science Core Collection (WoSCC) database, we used the bibliometric tools, including CiteSpace, VOS viewer, and alluvial generator, to visualize the scientific achievements on MB.

Results

A total of 630 articles were included. The number of published articles was in a fluctuating growth trend. These publications came from 37 contries, led by the USA and China. The leading country on MB was the United States, the leading position among institutions was Stanford University, and the most productive researcher on MB was Jennifer A. Tremmel. After analysis, the most common keywords were myocardial bridge, mortality, coronary angiography, descending coronary artery, and sudden death.

Conclusion

Our findings can aid researchers in understanding the current state of MB research and in choosing fresh lines of inquiry for forthcoming investigations. Prevalence and prognosis, mechanism atherosclerosis, hemodynamic significance, and molecular autops will likely become the focus of future research. In addition, more studies and cooperations are still needed worldwide.

Case report: Diagnosis of apical hypertrophic cardiomyopathy that escaped clinical and echocardiographic investigations for twenty years: Reasons and clinical implications

Background

Apical hypertrophic cardiomyopathy (ApHCM) is a rare form of hypertrophic cardiomyopathy which predominantly affects the apex of the left ventricle. The diagnosis can be challenging due to several factors, ranging from no typical clinical and electrocardiogram (EKG) findings to potential difficulties in executing and interpreting the echocardiographic examination.

Case presentation

We report the case of an 84-year-old woman who came to our echo-lab to undergo a routine echocardiogram. She had a history of permanent atrial fibrillation, paced rhythm and previous episodes of heart failure (HF), allegedly explained by a diagnosis of hypertensive heart disease that had been confirmed many times over the previous 20 years. The clinical examination and the EKG were unremarkable. The echocardiographic images were poor quality. But a senior cardiologist, expert in imaging and echocardiography, noted the lack of delineation of the endocardial border of the left ventricular (LV) apex region. Contrast echocardiography was performed and severe apical hypertrophy discovered.

Conclusion

ApHCM can be a challenging diagnosis. Contrast echocardiography must always be applied in cases of poor delineation of the LV apical endocardial border at baseline echocardiography. Timely detection and appropriate lifestyle intervention might slow the development of LV hypertrophy, and possibly minimize and delay heart failure (HF) related symptoms and arrhythmias. The prognosis remains relatively benign during long term follow-up.

Beyond Coronary Artery Disease: Assessing the Microcirculation

Ischemic heart disease (IHD) affects more than 20 million adults in the United States. Although classically attributed to atherosclerosis of the epicardial coronary arteries, nearly half of patients with stable angina and IHD who undergo invasive coronary angiography do not have obstructive epicardial coronary artery disease. Ischemia with nonobstructive coronary arteries is frequently caused by microvascular angina with underlying coronary microvascular dysfunction (CMD). Greater understanding the pathophysiology, diagnosis, and treatment of CMD holds promise to improve clinical outcomes of patients with ischemic heart disease.

Coronary Slow Flow Is Not Diagnostic of Microvascular Dysfunction in Patients With Angina and Unobstructed Coronary Arteries

Background Guidelines recommend that coronary slow flow phenomenon (CSFP), defined as corrected thrombolysis in myocardial infarction frame count (CTFC) >$$ > $$27, can diagnose coronary microvascular dysfunction (CMD) in patients with angina and nonobstructed coronary arteries. CSFP has also historically been regarded as a sign of coronary endothelial dysfunction (CED). We sought to validate the utility of CTFC, as a binary classifier of CSFP and as a continuous variable, to diagnose CMD and CED. Methods and Results Patients with angina and nonobstructed coronary arteries had simultaneous coronary pressure and flow velocity measured using a dual sensor-tipped guidewire during rest, adenosine-mediated hyperemia, and intracoronary acetylcholine infusion. CMD was defined as the inability to augment coronary blood flow in response to adenosine (coronary flow reserve <2.5) and CED in response to acetylcholine (acetylcholine flow reserve ≤1.5); 152 patients underwent assessment using adenosine, of whom 82 underwent further acetylcholine testing. Forty-six patients (30%) had CSFP, associated with lower flow velocity and higher microvascular resistance as compared with controls (16.5±$$ \pm $$6.9 versus 20.2±$$ \pm $$6.9 cm/s; P=0.001 and 6.26±$$ \pm $$1.83 versus 5.36±$$ \pm $$1.83 mm Hg/cm/s; P=0.009, respectively). However, as a diagnostic test, CSFP had poor sensitivity and specificity for both CMD (26.7% and 65.2%) and CED (21.1% and 56.0%). Furthermore, on receiver operating characteristics analyses, CTFC could not predict CMD or CED (area under the curve, 0.41 [95% CI, 0.32%-0.50%] and 0.36 [95% CI, 0.23%-0.49%], respectively). Conclusions In patients with angina and nonobstructed coronary arteries, CSFP and CTFC are not diagnostic of CMD or CED. Guidelines supporting the use of CTFC in the diagnosis of CMD should be revisited.

Pathophysiology and Outcomes of Endothelium Function in Coronary Microvascular Diseases: A Systematic Review of Randomized Controlled Trials and Multicenter Study

BACKGROUND

Coronary macrovascular disease is a concept that has been well-studied within the literature and has long been the subject of debates surrounding coronary artery bypass grafting (CABG) vs. Percutaneous Coronary Intervention (PCI). ISCHEMIA trial reported no statistical difference in the primary clinical endpoint between initial invasive management and initial conservative management, while in the ORBITA trial PCI did not improve angina frequency score significantly more than placebo, albeit PCI resulted in more patient-reported freedom from angina than placebo. However, these results did not prove the superiority of the PCI against OMT, therefore do not indicate the benefit of PCI vs. the OMT. Please rephrase the sentence. We reviewed the role of different factors responsible for endothelial dysfunction from recent randomized clinical trials (RCTs) and multicentre studies.

METHODS

A detailed search strategy was performed using a dataset that has previously been published. Data of pooled analysis include research articles (human and animal models), CABG, and PCI randomized controlled trials (RCTs). Details of the search strategy and the methods used for data pooling have been published previously and registered with Open-Source Framework.

RESULTS

The roles of nitric oxide (NO), endothelium-derived contracting factors (EDCFs), and vasodilator prostaglandins (e.g., prostacyclin), as well as endothelium-dependent hyperpolarization (EDH) factors, are crucial for the maintenance of vasomotor tone within the coronary vasculature. These homeostatic mechanisms are affected by sheer forces and other several factors that are currently being studied, such as vaping. The role of intracoronary testing is crucial when determining the effects of therapeutic medications with further studies on the horizon.

CONCLUSION

The true impact of coronary microvascular dysfunction (CMD) is perhaps underappreciated, which supports the role of medical therapy in determining outcomes. Ongoing trials are underway to further investigate the role of therapeutic agents in secondary prevention.

Impairment in quantitative microvascular function in non-ischemic cardiomyopathy as demonstrated using cardiovascular magnetic resonance

Background

Microvascular dysfunction (MVD) is present in various cardiovascular diseases and portends worse outcomes. We assessed the prevalence of MVD in patients with non-ischemic cardiomyopathy (NICM) as compared to subjects with preserved ejection fraction (EF) using stress cardiovascular magnetic resonance (CMR).

Methods

We retrospectively studied consecutive patients with NICM and 58 subjects with preserved left ventricular (LV) EF who underwent stress CMR between 2011–2016. MVD was defined visually as presence of a subendocardial perfusion defect and semiquantitatively by myocardial perfusion reserve index (MPRI<1.51). MPRI was compared between groups using univariate analysis and multivariable linear regression.

Results

In total, 41 patients with NICM (mean age 51 ± 14, 59% male) and 58 subjects with preserved LVEF (mean age 51 ± 13, 31% male) were identified. In the NICM group, MVD was present in 23 (56%) and 11 (27%) by semiquantitative and visual evaluation respectively. Compared to those with preserved LVEF, NICM patients had lower rest slope (3.9 vs 4.9, p = 0.05) and stress perfusion slope (8.8 vs 11.7, p<0.001), and MPRI (1.41 vs 1.74, p = 0.02). MPRI remained associated with NICM after controlling for age, gender, hypertension, ethnicity, diabetes, and late gadolinium enhancement (log MPR, β coefficient = -0.19, p = 0.007).

Conclusions

MVD—as assessed using CMR—is highly prevalent in NICM as compared to subjects with preserved LVEF even after controlling for covariates. Semiquantitative is able to detect a greater number of incidences of MVD compared to visual methods alone. Further studies are needed to determine whether treatment of MVD is beneficial in NICM.

Prognostic Impact of Coronary Flow Reserve in Patients With CKD

Introduction

Both coronary flow reserve (CFR) and chronic kidney disease (CKD) are known to be associated with adverse cardiac events. However, it is unclear how these prognostic factors are interrelated. This study evaluated the association between intracoronary physiologic indexes and CKD and their prognostic implications.

Methods

A total of 351 patients without left ventricular systolic dysfunction (ejection fraction ≥ 40%) and not on dialysis whose revascularization was deferred based on fractional flow reserve (FFR) > 0.80 were analyzed. Depressed CFR was defined as CFR ≤ 2.0. The primary outcome was a composite of cardiac death or hospitalization for heart failure at 3 years.

Results

Patients with CKD showed lower CFR than the non-CKD population (3.28 ± 1.77 vs. 2.60 ± 1.09, P < 0.001), mainly driven by increased resting coronary flow. There was no significant difference in hyperemic coronary flow, FFR, and index of microvascular resistance between the 2 groups. CFR was significantly associated with estimated glomerular filtration rate (eGFR) (P = 0.045), and the proportion of depressed CFR was significantly increased with higher CKD stages (P = 0.011). The risk of cardiac death or hospitalization for heart failure was the lowest in the non-CKD and preserved CFR group (11.9%) and the highest in the CKD and depressed CFR group (60.0%, overall log rank P < 0.001). Both CKD (adjusted hazard ratio [HR_adj] 2.614, 95% confidence interval [CI] 1.505-4.539, P < 0.001) and depressed CFR (HR_adj 3.237, 95% CI 2.015-5.199, P < 0.001) were independently associated with the risk of the primary outcome.

Conclusion

There was a significant association between severity of CKD and CFR. Both CKD and depressed CFR showed independent association with higher risk of cardiac death or hospitalization for heart failure.

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.

Determination of [N-13]-ammonia extraction fraction in patients with coronary artery disease by calibration to invasive coronary and fractional flow reserve

BACKGROUND

This study presents a new extraction fraction (EF) model based on physiological measures of invasive coronary flow reserve (CFR) and fractional flow reserve (FFR) in patients with suspected coronary artery disease (CAD) and normal index microcirculatory resistance (IMR). To ascertain the clinical relevance of the new EFs, flow measurements using the newly patient-determined EFs were compared to flow measurements using traditional animal-determined EFs.

METHODS

39 patients were retrospectively selected that included a total of 91 vascular territories with invasive coronary angiography physiological measures. [N-13]-ammonia dynamic rest/adenosine-stress PET imaging was conducted in all patients and absolute myocardial flow was estimated using four published compartmental models. The extraction fraction during hyperemic flow was iteratively estimated by maximizing the agreement between invasive CFR and FFR with the non-invasive analogs myocardial flow reserve (MFR) and relative flow reserve (RFR) at similar physiological states, respectively.

RESULTS

Using the new patient-determined EFs, agreement between CFR vs MFR for Model 1 and 2 was moderate and poor for Model 3 and 4. All models showed moderate agreement for FFR vs RFR. When using published models of animal-determined EFs, agreement between CFR vs MFR remained moderate for Model 1 and 2, and poor for Model 3 and 4. Similarly, all models showed moderate agreement for FFR vs RFR using animal-determined EF values. None of the observed differences were statistically significant.

CONCLUSIONS

Flow measurements using extraction fraction correction for [N-13]-ammonia based on calibration to invasive intracoronary angiography physiological measures in patients with CAD were not discordant from those reported in the literature. Either patient-determined or traditional animal-determined EF correction, when used with the appropriate flow model, yields moderate agreement with invasive measurements of coronary flow reserve and fractional flow reserve.

Colocalization of Coronary Plaque with Wall Shear Stress in Myocardial Bridge Patients

PURPOSE

Patients with myocardial bridges (MBs) have a higher prevalence of atherosclerosis. Wall shear stress (WSS) has previously been correlated with plaque in coronary artery disease patients, but such correlations have not been investigated in symptomatic MB patients. The aim of this paper was to use a multi-scale computational fluid dynamics (CFD) framework to simulate hemodynamics in MB patient, and investigate the co-localization of WSS and plaque.

METHODS

We identified N = 10 patients from a previously reported cohort of 50 symptomatic MB patients, all of whom had plaque in the proximal vessel. Dynamic 3D models were reconstructed from coronary computed tomography angiography (CCTA), intravascular ultrasound (IVUS) and catheter angiograms. CFD simulations were performed to compute WSS proximal to, within and distal to the MB. Plaque was quantified from IVUS images in 2 mm segments and registered to CFD model. Plaque area was compared to absolute and patient-normalized WSS.

RESULTS

WSS was lower in the proximal segment compared to the bridge segment (6.1 ± 2.9 vs. 16.0 ± 7.1 dynes/cm², p value < 0.01). Plaque area and plaque burden measured from IVUS peaked at 1-3 cm proximal to the MB entrance, coinciding with the first diagonal branch. Normalized WSS showed a statistically significant moderate correlation with plaque area (r = 0.41, p < 0.01).

CONCLUSION

WSS may be obtained non-invasively in MB patients and provides a surrogate marker of plaque area. Using CFD, it may be possible to non-invasively assess the extent of plaque area, and identify patients who could benefit from frequent monitoring or medical management.

Clinical Practice Variations in the Management of Ischemia With No Obstructive Coronary Artery Disease

Background Ischemia with no obstructive coronary artery disease is a condition associated with major adverse cardiovascular outcomes. To date, there are no specific American Heart Association or American College of Cardiology guidelines. The objective of this survey is to better understand the clinical practice and knowledge gaps that exist nationally. Methods and Results Participant-specific links for a survey with 11 questions and 3 reminders were sent between September and October 2020 to the American College of Cardiology CardioSurve Panel. The panel consist of randomly selected cardiologists (n=437) who represent the current profile of the American College of Cardiology US membership. The survey received a 30% response rate. Of the 172 respondents, 130 (76%) indicated that they have treated patients with ischemia with no obstructive coronary artery disease. Although the majority (69%) are generally confident in their ability to manage this condition, 1 of 3 report lack of confidence or are neutral. The American College of Cardiology/American Heart Association Chronic Stable Angina Guidelines are the most commonly used reference for treating ischemia with no obstructive coronary artery disease (81%), with most cardiologists wanting additional clinical guidance, such as randomized controlled trials (61%). More than 4 of 5 cardiologists rarely or never order advanced imaging modalities to assess coronary flow reserve. Approximately 2 of 3 of respondents frequently prescribe statins (68%), aspirin (66%), calcium channel blockers (63%), and β blockers or α/β blockers (55%). However, nearly 70% never prescribe angiotensin-converting enzyme inhibitors or angiotensin receptor blockers. Conclusions This survey demonstrates heterogeneity in the management of ischemia with no obstructive coronary artery disease among US cardiologists, identifies support for guideline development, and outlines knowledge gaps for research and education in the therapeutic management of this condition.

Hidden Coronary Atherosclerosis Assessment but Not Coronary Flow Reserve Helps to Explain the Slow Coronary Flow Phenomenon in Patients with Angiographically Normal Coronary Arteries

The significance of the slow coronary flow phenomenon (SCFph), as visualized in patients (pts) with angiographically normal coronary arteries, is controversial. Absolute coronary flow reserve (CFR) in the left anterior descending coronary artery (LAD), non-invasively assessed by a transthoracic color-guided pulsed-wave Doppler (E-Doppler TTE), is a reliable parameter to assess coronary microcirculatory dysfunction (CMD). Mild and angiographically hidden epicardial atherosclerosis (Hath), as visualized by intracoronary ultrasound (IVUS), which could be the clue to atherosclerotic coronary microvascular involvement, has never been investigated together with CFR in patients. This study was aimed at assessing the value of CFR and HA in explaining the SCFph. Methods. Both non-invasive assessment of CFR in the LAD and corrected TIMI frame count assessment of the coronary contrast runoff were performed in 124 pts with angiographically normal coronary arteries. Among the whole group, 32 patients also underwent intracoronary ultrasounds in the LMCA and LAD, and the maximal plaque burden was assessed (Lesion external elastic (EEM) cross sectional area (CSA)—Lesion Lumen CSA/Lesion EEM CSA * 100). We found that 24 of the 124 pts (group 1) had the SCFph and the remaining 100 had a normal runoff (group 2). CFR, evaluated in both groups, was not significantly different, being 2.79 ± 0.79 (Mean ± SD) in group 1 and 2.90 ± 0.8 in group 2 (p = ns); in the pts also examined by IVUS (32 pts), the SCFph was always associated with hidden atherosclerosis, and a plaque burden of ≥33%. On the contrary, in the normal runoff group, any grade of PB was observed (from no athero to a PB > 70%) and remarkably, 10 pts had no signs of athero or just a minimal plaque burden. This resulted in a ROC curve analysis in which PB < 33% had a high negative predictive value (100%) in ruling out the SCFph. In addition, considering a CFR value < 2.21 as an index of coronary microcirculatory dysfunction, we found CMD in 15 pts (15%) in group 1 and in 7 pts (29%) in group 2 (p = ns). In conclusion, the SCFph is strongly connected to epicardial athero to the extent that the absence of hidden coronary athero has a very high negative predictive power in ruling out SCFph. CFR that is based on an endothelium-independent mechanism remains fairly normal in this condition. An endothelium-dependent microcirculatory constriction at rest due to atherosclerotic involvement of the coronary microvascular network is a possible explanation of the SCFph.

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

BACKGROUND

Coronary function testing in patients with ischemia and nonobstructive coronary arteries (INOCA) commonly includes assessment of adenosine-mediated vasodilation and acetylcholine spasm provocation. The purpose of this study was to evaluate the diagnostic value of additional endothelial function testing for the diagnosis of vasomotor dysfunction in patients with INOCA.

METHODS

In this retrospective cohort study, we included patients with INOCA who underwent clinically indicated comprehensive coronary function testing. Endothelial dysfunction was defined as a <50% increase in coronary blood flow, determined by Doppler flow, and/or epicardial vasoconstriction compared to baseline, in response to low-dose acetylcholine. Coronary artery spasm (CAS) was defined as vasospastic angina or microvascular angina in response to coronary high-dose acetylcholine. An impaired adenosine-mediated vasodilation was defined as a coronary flow reserve <2.5 and/or hyperemic microvascular resistance ≥2.5.

RESULTS

Among all 110 patients, 79% had endothelial dysfunction, 62% had CAS, and 29% had an impaired adenosine-mediated vasodilation. Endothelial dysfunction was present in 80% of patients who tested positively for CAS and/or an impaired adenosine-mediated vasodilation. Endothelial function testing increases the diagnostic yield of coronary function testing that only incorporates adenosine testing and spasm provocation by 17% to 92%. Of patients with normal adenosine-mediated vasodilation and no inducible CAS, 68% had endothelial dysfunction.

CONCLUSIONS

Concomitant endothelial dysfunction was prevalent in the vast majority of patients with INOCA with inducible CAS and/or an impaired adenosine-mediated vasodilation. In patients with INOCA without inducible CAS and normal adenosine-mediated vasodilation, two-thirds had endothelial dysfunction. These results indicate the relevance to perform endothelial function testing in patients with INOCA in view of its therapeutic implication.

Perspectives in noninvasive imaging for chronic coronary syndromes

Both the latest European guidelines on chronic coronary syndromes and the American guidelines on chest pain have underlined the importance of noninvasive imaging to select patients to be referred to invasive angiography. Nevertheless, although coronary stenosis has long been considered the main determinant of inducible ischemia and symptoms, growing evidence has demonstrated the importance of other underlying mechanisms (e.g., vasospasm, microvascular disease, energetic inefficiency). The search for a pathophysiology-driven treatment of these patients has therefore emerged as an important objective of multimodality imaging, integrating "anatomical" and "functional" information. We here provide an up-to-date guide for the choice and the interpretation of the currently available noninvasive anatomical and/or functional tests, focusing on emerging techniques (e.g., coronary flow velocity reserve, stress-cardiac magnetic resonance, hybrid imaging, functional-coronary computed tomography angiography, etc.), which could provide deeper pathophysiological insights to refine diagnostic and therapeutic pathways in the next future.

A novel CFD-based computed index of microcirculatory resistance (IMR) derived from coronary angiography to assess coronary microcirculation

OBJECTIVES

This study sought to present a novel approach for computation of the index of microcirculatory resistance (IMR) and to evaluate its diagnostic performance.

BACKGROUND

IMR is a quantitative assessment to identify coronary microvascular dysfunction. However, its clinical use remains extremely limited. Calculation of IMR from coronary angiography images may increase the utility of coronary microvasculature assessment.

METHODS

203 patients with 203 vessels were included in this study. Physiology measurements were obtained with pressure-wire in the whole cohort. The computational fluid dynamics (CFD)-based AccuIMR was computed and evaluated in a blinded fashion using wire-based IMR as the reference standard.

RESULTS

The overall diagnostic accuracy, sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of AccuIMR for detecting coronary microvascular disease were 91.1% (95% CI: 86.4% to 94.7%), 89.4% (95% CI: 80.9% to 95.0%), 92.4% (95% CI: 86.0% to 96.5%), 89.4% (95% CI: 81.8% to 94.1%), and 92.2% (95% CI: 86.7% to 95.8%), respectively. The correlation coefficient equaled to 0.81 (p < 0.001) between AccuIMR and wire-based IMR with the receiver-operating curve had area under the curve of 0.924 (95% CI: 0.878 to 0.956).

CONCLUSIONS

AccuIMR is a novel pressure-wire free approach to assess coronary microvascular disease with great diagnostic performance, which can be a valid, efficient, and cost-reducing tool to provide an easier routine assessment of coronary microcirculation.

Pressure- and 3D-Derived Coronary Flow Reserve with Hydrostatic Pressure Correction: Comparison with Intracoronary Doppler Measurements

Purpose: To develop a method of coronary flow reserve (CFR) calculation derived from three-dimensional (3D) coronary angiographic parameters and intracoronary pressure data during fractional flow reserve (FFR) measurement. Methods: Altogether 19 coronary arteries of 16 native and 3 stented vessels were reconstructed in 3D. The measured distal intracoronary pressures were corrected to the hydrostatic pressure based on the height differences between the levels of the vessel orifice and the sensor position. Classical fluid dynamic equations were applied to calculate the flow during the resting state and vasodilatation based on morphological data and intracoronary pressure values. 3D-derived coronary flow reserve (CFRp-3D) was defined as the ratio between the calculated hyperemic and the resting flow and was compared to the CFR values simultaneously measured by the Doppler sensor (CFRDoppler). Results: Haemodynamic calculations using the distal coronary pressures corrected for hydrostatic pressures showed a strong correlation between the individual CFRp-3D values and the CFRDoppler measurements (r = 0.89, p < 0.0001). Hydrostatic pressure correction increased the specificity of the method from 46.1% to 92.3% for predicting an abnormal CFRDoppler < 2. Conclusions: CFRp-3D calculation with hydrostatic pressure correction during FFR measurement facilitates a comprehensive hemodynamic assessment, supporting the complex evaluation of macro-and microvascular coronary artery disease.

A Practical Approach to Invasive Testing in Ischemia with No Obstructive Coronary Arteries (INOCA)

Up to 65% of women and approximately 30% of men have ischemia with no obstructive coronary artery disease (CAD; commonly known as INOCA) on invasive coronary angiography performed for stable angina. INOCA can be due to coronary microvascular dysfunction or coronary vasospasm. Despite the absence of obstructive CAD, those with INOCA have an increased risk of all-cause mortality and adverse outcomes, including recurrent angina and cardiovascular events. These patients often undergo repeat testing, including cardiac catheterization, resulting in lifetime healthcare costs that rival those for obstructive CAD. Patients with INOCA often remain undiagnosed and untreated. This review discusses the symptoms and prognosis of INOCA, offers a systematic approach to the diagnostic evaluation of these patients, and summarizes therapeutic management, including tailored therapy according to underlying pathophysiological mechanisms.

Coronary microvascular disease: The "Meeting Point" of Cardiology, Rheumatology and Endocrinology

BACKGROUND

Exertional chest pain/dyspnea or chest pain at rest are the main symptoms of coronary artery disease (CAD), which are traditionally attributed to insufficiency of the epicardial coronary arteries. However, 2/3 of women and 1/3 of men with angina and 10% of patients with acute myocardial infarction have no evidence of epicardial coronary artery stenosis in X-ray coronary angiography. In these cases, coronary microvascular disease (CMD) is the main causative factor.

AIMS

To present the pathophysiology of CMD in Cardiology, Rheumatology and Endocrinology.

MATERIALS-METHODS

The pathophysiology of CMD in Cardiology, Rheumatology and Endocrinology was evaluated. It includes impaired microvascular vasodilatation, which leads to inability of the organism to deal with myocardial oxygen needs and, hence, development of ischemic pain. CMD, observed in inflammatory autoimmune rheumatic and endocrine/metabolic disorders, brings together Cardiology, Rheumatology and Endocrinology. Causative factors include persistent systemic inflammation and endocrine/metabolic abnormalities influencing directly the coronary microvasculature. In the past, the evaluation of microcirculation was feasible only with the use of invasive techniques, such as coronary flow reserve assessment. Currently, the application of advanced imaging modalities, such as cardiovascular magnetic resonance (CMR), can evaluate CMD non-invasively and without ionizing radiation.

RESULTS

CMD may present with a variety of symptoms with 1/3 to 2/3 of them expressed as typical chest pain in effort, more commonly found in women during menopause than in men. Atypical presentation includes chest pain at rest or exertional dyspnea,but post exercise symptoms are not uncommon. The treatment with nitrates is less effective in CMD, because their vasodilator action in coronary micro-circulation is less pronounced than in the epicardial coronary arteries.

DISCUSSION

Although both classic and new medications have been used in the treatment of CMD, there are still many questions regarding both the pathophysiology and the treatment of this disorder. The potential effects of anti-rheumatic and endocrine medications on the evolution of CMD need further evaluation.

CONCLUSION

CMD is a multifactorial disease leading to myocardial ischemia/fibrosis alone or in combination with epicardial coronary artery disease. Endothelial dysfunction/vasospasm, systemic inflammation, and/or neuroendocrine activation may act as causative factors and bring Cardiology, Rheumatology and Endocrinology together. Currently, the application of advanced imaging modalities, and specifically CMR, allows reliable assessment of the extent and severity of CMD. These measurements should not be limited to "pure cardiac patients", as it is known that CMD affects the majority of patients with autoimmune rheumatic and endocrine/metabolic disorders.