Management of ischaemia with non-obstructive coronary arteries (INOCA)

Endothelial microRNAs in INOCA patients with diabetes mellitus

Ischemia with non-obstructive coronary artery (INOCA) is a common cause of hospital admissions, leading to negative outcomes and reduced quality of life. Central to its pathophysiology is endothelial dysfunction, which contributes to myocardial ischemia despite the absence of significant coronary artery blockage. Addressing endothelial dysfunction is essential in managing INOCA to alleviate symptoms and prevent cardiovascular events. Recent studies have identified diabetes mellitus (DM) as a significant factor exacerbating INOCA complications by promoting endothelial impairment and coronary microvascular dysfunction. MicroRNAs (miRNAs) have emerged as potential biomarkers and therapeutic targets in various biological processes, including endothelial dysfunction and cardiovascular diseases. However, research on miRNA biomarkers in INOCA patients is sparse. In this study, we examined a panel of circulating miRNAs involved in the regulation of endothelial function in INOCA patients with and without DM. We analyzed miRNA expression using RT-qPCR in a cohort of consecutive INOCA patients undergoing percutaneous coronary intervention. We detected a significant dysregulation of miR-363-5p and miR-92a-3p in INOCA patients with DM compared to those without DM, indicating their role as biomarkers for predicting and monitoring endothelial dysfunction in INOCA patients with DM.

New avenues for the assessment of stable ischemic heart disease

Myocardial ischemia is a complex condition which may result from epicardial and/or microvascular causes involving functional and structural mechanisms. These mechanisms may overlap in a given patient illustrating the difficulties for appropriate management. Assessment of myocardial ischemia can be performed using noninvasive and invasive tools. However, despite living in the era of individualized precision medicine, these tools are not yet used in a broader fashion. Emerging noninvasive techniques such as quantitative perfusion cardiac magnetic resonance imaging (CMR) and stress perfusion computed tomography (CT) or photon-counting CT techniques may contribute to new standards in the assessment of stable angina patients. Invasive evaluation of myocardial ischemia should not only focus on hemodynamically relevant epicardial disease but also involve coronary vasomotor function testing (coronary spasm, coronary flow reserve, and microvascular resistance) where appropriate. Optimal patient management will depend on accurate and comprehensive diagnostic evaluation of myocardial ischemia and development of new treatment options in the future.

Triglyceride-glucose index is associated with myocardial ischemia and poor prognosis in patients with ischemia and no obstructive coronary artery disease

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) is increasingly recognized and associated with poor outcomes. The triglyceride-glucose (TyG) index is a reliable alternative measure of insulin resistance significantly linked to cardiovascular disease and adverse prognosis. We investigated the association between the TyG index and myocardial ischemia and the prognosis in INOCA patients.

METHODS

INOCA patients who underwent both coronary angiography and myocardial perfusion imaging (MPI) were included consecutively. All participants were divided into three groups according to TyG tertiles (T1, T2, and T3). Abnormal MPI for myocardial ischemia in individual coronary territories was defined as summed stress score (SSS) ≥ 4 and summed difference score (SDS) ≥ 2. SSS refers to the sum of all defects in the stress images, and SDS is the difference of the sum of all defects between the rest images and stress images. All patients were followed up for major adverse cardiac events (MACE).

RESULTS

Among 332 INOCA patients, 113 (34.0%) had abnormal MPI. Patients with higher TyG index had a higher rate of abnormal MPI (25.5% vs. 32.4% vs. 44.1%; p = 0.012). Multivariate logistic analysis showed that a high TyG index was significantly correlated with abnormal MPI in INOCA patients (OR, 1.901; 95% CI, 1.045-3.458; P = 0.035). During the median 35 months of follow-up, 83 (25%) MACE were recorded, and a higher incidence of MACE was observed in the T3 group (T3 vs. T2 vs. T1: 36.9% vs. 21.6% vs. 16.4%, respectively; p = 0.001). In multivariate Cox regression analysis, the T3 group was significantly associated with the risk of MACE compared to the T1 group (HR, 2.338; 95% CI 1.253-4.364, P = 0.008).

CONCLUSION

This study indicates for the first time that the TyG index is significantly associated with myocardial ischemia and poor prognosis among INOCA patients.

Sex-specific and ethnicity-specific differences in MINOCA

Suspected myocardial infarction with non-obstructive coronary arteries (MINOCA) has received increasing attention over the past decade. Given the heterogeneity in the mechanisms underlying acute myocardial infarction in the absence of obstructive coronary arteries, the syndrome of MINOCA is considered a working diagnosis that requires further investigation after diagnostic angiography studies have been performed, including coronary magnetic resonance angiography and functional angiography. Although once considered an infrequent and low-risk form of myocardial infarction, recent data have shown that the prognosis of MINOCA is not as benign as previously assumed. However, despite increasing awareness of the condition, many questions remain regarding the diagnosis, risk stratification and treatment of MINOCA. Women seem to be more susceptible to MINOCA, but studies on the sex-specific differences of the disease are scarce. Similarly, ethnicity-specific factors might explain discrepancies in the observed prevalence or underlying pathophysiological mechanisms of MINOCA but data are also scarce. Therefore, in this Review, we provide an update on the latest evidence available on the sex-specific and ethnicity-specific differences in the clinical features, pathophysiological mechanisms, treatment and prognosis of MINOCA.

Spherization indices measured by resting SPECT improve risk stratification in patients with ischemia with non-obstructive coronary artery disease (INOCA)

BACKGROUND

The prevalence of ischemia with non-obstructive coronary artery disease (INOCA) is substantial, but its risk stratification has been suboptimal. Resting SPECT myocardial perfusion imaging (MPI) could provide useful heart information including spherical indices. We aimed to evaluate the prognostic value of spherical indices in individuals with INOCA.

RESULTS

During a median follow-up of 47.2 ± 20.8 months, 49 (17.2%) patients experienced major adverse cardiac events (MACE). Compared to those without MACE, those with MACE had a higher shape index (SI) (0.60 ± 0.07 vs. 0.58 ± 0.06; P = 0.028) and a lower E2 (eccentricity index calculated by the QPS) (0.81 ± 0.05 vs. 0.83 ± 0.04; P = 0.019). MACE event-free survival analysis revealed significant differences in the SI and E2 among all patients (all log-rank P < 0.01). Multivariate Cox analysis showed abnormal SI (HR: 2.73, 95% CI 1.44-5.18, P = 0.002) and E2 (HR: 1.94, 95% CI 1.08-3.48, P = 0.026) were both independent predictors for MACE when they were put into the same model, respectively. The incorporation of the SI into the baseline model demonstrated a significant improvement in the predictive accuracy for MACEs (P = 0.026), whereas E2 did not exhibit a similar improvement (P > 0.05).

CONCLUSION

For patients with INOCA, spherical indices (especially the SI) were associated with long-term MACE, which could be a preferable indicator for risk stratification and prognostic prediction.

Targeted Therapies for Microvascular Disease

Coronary microvascular dysfunction (CMD) is a common cause of ischemia but no obstructive coronary artery disease that results in an inability of the coronary microvasculature to meet myocardial oxygen demand. CMD is challenging to diagnose and manage due to a lack of mechanistic research and targeted therapy. Recent evidence suggests we can improved patient outcomes by stratifying antianginal therapies according to the diagnosis revealed by invasive assessment of the coronary microcirculation. This review article appraises the evidence for management of CMD, which includes treatment of cardiovascular risk, antianginal therapy and therapy for atherosclerosis.

Targeted Therapies for Microvascular Disease

Coronary microvascular dysfunction (CMD) is a common cause of ischemia but no obstructive coronary artery disease that results in an inability of the coronary microvasculature to meet myocardial oxygen demand. CMD is challenging to diagnose and manage due to a lack of mechanistic research and targeted therapy. Recent evidence suggests we can improved patient outcomes by stratifying antianginal therapies according to the diagnosis revealed by invasive assessment of the coronary microcirculation. This review article appraises the evidence for management of CMD, which includes treatment of cardiovascular risk, antianginal therapy and therapy for atherosclerosis.

The role of left ventricular hypertrophy measured by echocardiography in screening patients with ischaemia with non-obstructive coronary arteries: a cross-sectional study

Many patients with ischaemia with non-obstructive coronary arteries (INOCA) have a poor prognosis. This study aims to explore the diagnostic value of left ventricular hypertrophy (LVH)-related ultrasound parameters in INOCA patients. The study group consisted of 258 patients with INOCA in this retrospective cross-sectional study, and these patients were free of obstructive coronary artery disease, previous revascularization, atrial fibrillation, ejection fraction < 50%, major distortions of left ventricular geometry, suspected non-ischaemic causes. Control individuals were matched 1:1 with study group according to age, sex, cardiovascular risk factors, and time of hospital stay. According to left ventricular mass index (LVMI) and relative wall thickness, left ventricular geometry was composed of concentric hypertrophy, eccentric hypertrophy, concentric remodeling and normal geometry. LVH-related parameters, left ventricular geometry, demographic characteristics, laboratory parameters and other echocardiographic indicators were compared between the two groups. Subgroup analysis was performed based on sex. LVMI in the study group was higher than that in the control group (86.86 ± 18.83 g/m2 vs 82.25 ± 14.29 g/m2, P = 0.008). The ratio of LVH was higher in the study group (20.16% vs 10.85%, P = 0.006). After subgroup analysis based on sex, LVMI differences (85.77 ± 18.30 g/m2 vs 81.59 ± 14.64 g/m2, P = 0.014) and the ratio of LVH differences (25.00% vs 14.77%, P = 0.027) still existed in females between the two groups. There was no difference in the constituent ratio of left ventricular geometry between the two groups (P = 0.157). Sex-based subgroup analysis showed no difference in the constituent ratio of left ventricular geometry between the two groups in females (P = 0.242). The degree of LVH in the study group was higher than that in the control group, suggesting that LVH may play an important role in the occurrence and development of INOCA. Moreover, LVH-related ultrasound parameters may be of higher diagnostic value for female INOCA patients than for male INOCA patients.

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.

Factors Associated with Impaired Resistive Reserve Ratio and Microvascular Resistance Reserve

Coronary microvascular dysfunction (CMD) is described as an important subset of ischemia with no obstructive coronary artery disease. Resistive reserve ratio (RRR) and microvascular resistance reserve (MRR) have been proposed as novel physiological indices evaluating coronary microvascular dilation function. The aim of this study was to explore factors associated with impaired RRR and MRR. Coronary physiological indices were invasively evaluated in the left anterior descending coronary artery using the thermodilution method in patients suspected of CMD. CMD was defined as a coronary flow reserve <2.0 and/or index of microcirculatory resistance ≥25. Of 117 patients, 26 (24.1%) had CMD. RRR (3.1 ± 1.9 vs. 6.2 ± 3.2, p < 0.001) and MRR (3.4 ± 1.9 vs. 6.9 ± 3.5, p < 0.001) were lower in the CMD group. In the receiver operating characteristic curve analysis, RRR (area under the curve 0.84, p < 0.001) and MRR (area under the curve 0.85, p < 0.001) were both predictive of the presence of CMD. In the multivariable analysis, previous myocardial infarction, lower hemoglobin, higher brain natriuretic peptide levels, and intracoronary nicorandil were identified as factors associated with lower RRR and MRR. In conclusion, the presence of previous myocardial infarction, anemia, and heart failure was associated with impaired coronary microvascular dilation function. RRR and MRR may be useful to identify patients with CMD.

Clinical and psychological characteristics of patients with ischemia and non-obstructive coronary arteries (INOCA) and obstructive coronary artery disease

Study objective

Ischemia with non-obstructive coronary arteries (INOCA) is caused by vascular dysfunctions and predominantly seen in women. For better recognition and prevention more insight is needed on risk factors and well-being. We aimed to explore differences in psychological distress, quality of life, risk factors, and medication use between women with INOCA and obstructive coronary artery disease (CAD).

Methods

Patients from two separate studies (n = 373, 57 % women) completed a questionnaire assessing psychological and clinical factors. Analyses were performed for women only who were categorized into three groups: non-ischemic chest pain (n = 115), INOCA (n = 68), and obstructive CAD (n = 30). Secondary analyses were performed for men only, and sex differences within INOCA patients were explored.

Results and conclusion

Compared to obstructive CAD patients, INOCA patients reported better physical functioning (p = 0.041). Furthermore, INOCA patients had less often hypercholesterolemia (p < 0.001), were less often active smokers (p = 0.062), had a lower mean BMI (p = 0.022), and reported more often a familial history of CAD (p = 0.004). Patients with INOCA used antithrombotic, cholesterol lowering medications, and beta-blockers less often than patients with obstructive CAD. No differences between patients with INOCA and obstructive CAD were found for psychological distress, well-being, and for women-specific risk factors. The results suggest that women with INOCA experience similar levels of psychological distress and seem to have different risk factor profiles and are less optimally treated as compared to obstructive CAD patients. Further research on risk factors is needed for better prevention and treatment.

Stress Hyperglycemia Drives the Risk of Hospitalization for Chest Pain in Patients With Ischemia and Nonobstructive Coronary Arteries (INOCA)

OBJECTIVE

Ischemia with nonobstructive coronary arteries (INOCA) is a prevailing finding in patients with angina. However, the main factors underlying the risk of being rehospitalized for chest pain in patients with INOCA remain mostly unknown.

RESEARCH DESIGN AND METHODS

We evaluated INOCA patients referred to the "Casa di Cura Montevergine" in Mercogliano (Avellino), Italy, from January 2016 to January 2021 for percutaneous coronary intervention (PCI). In these subjects, we assessed the impact of the stress hyperglycemia ratio (SHR), defined as the ratio of mmol/L blood glucose and % HbA1c, on the risk of rehospitalization for chest pain.

RESULTS

A total of 2,874 patients with INOCA successfully completed the study. At the 1-year follow-up, the risk of rehospitalization for chest pain was significantly higher (P < 0.001) in INOCA patients with SHR >1 compared to patients with SHR ≤1. These findings were confirmed by multivariable analyses (adjusting for potential confounders, including age, BMI, blood pressure, heart rate, chronic kidney disease, and cholesterol), propensity score matching, and inverse probability of treatment weighting.

CONCLUSIONS

Our data indicate, to our knowledge for the first time, that SHR on hospital admission significantly and independently increases the risk of rehospitalization for chest pain in INOCA patients.

Targeted Therapies for Microvascular Disease

Coronary microvascular dysfunction (CMD) is a common cause of ischemia but no obstructive coronary artery disease that results in an inability of the coronary microvasculature to meet myocardial oxygen demand. CMD is challenging to diagnose and manage due to a lack of mechanistic research and targeted therapy. Recent evidence suggests we can improved patient outcomes by stratifying antianginal therapies according to the diagnosis revealed by invasive assessment of the coronary microcirculation. This review article appraises the evidence for management of CMD, which includes treatment of cardiovascular risk, antianginal therapy and therapy for atherosclerosis.

Endothelial dysfunction in patients with angina and non-obstructed coronary arteries is associated with an increased risk of mayor cardiovascular events. Results of the Spanish ENDOCOR registry

BACKGROUND

Coronary endothelial dysfunction and vasospasm are potential causes of ischemia in patients without obstructive coronary stenoses (INOCA).

OBJECTIVE

To evaluate the prevalence of endothelial dysfunction and the clinical profile of patients with INOCA in Spain, as well as to identify the predictors and the prognostic impact of endothelial dysfunction in this scenario.

METHODS

A total of 438 consecutive patients with INOCA in whom the acetylcholine test was performed were prospectively enrolled. Patients were followed up at 1 and 2 years.

RESULTS

Mean age was 62 ± 11 years with 60% female. Clinical presentation comprised 52.6% angina at rest, 61.2% exertional angina, and 31.7% dyspnea. There were no major complications of the acetylcholine test. Endothelial dysfunction was observed in 198 (45%) of patients, with severe vasoconstriction (defined as over 70% constriction), being observed in 101 (23%). Multivariable regression analysis showed that endothelial dysfunction was predicted by the presence of exertional angina (OR 2.2; CI95%1.01-2.55; p = 0.02), prior coronary disease (OR 2.46; CI95% 1.57-3.89; p < 0.01), and coronary intramyocardial bridging (2.35; CI95% 1.02-5.60; p = 0.04). Patients with endothelial dysfunction presented with worsening angina compared to those without endothelial dysfunction (25.6% vs. 12.8%) and also presented with increased levels of minimal effort angina (40% vs. 26,7%, p = 0.03) more frequently during the follow up than those without endothelial dysfunction. Endothelial dysfunction was also an independent predictor of the occurrence of myocardial infarction or unstable angina at one year (OR 2.85, CI 95% 1.01-9.25; p = 0.03).

CONCLUSIONS

Endothelial dysfunction is present in almost half of patients with INOCA and is associated with worsening symptoms, as well as with a higher rate of adverse events.

Effect of nonobstructive coronary stenosis on coronary microvascular dysfunction and long-term outcomes in patients with INOCA

BACKGROUND

Ischemic pain with no-obstructive coronary artery (INOCA) is clinically significant and defined by nonobstructive coronary stenosis <50%. Coronary microvascular dysfunction (CMD) is a relevant cause associated with adverse outcomes.

OBJECTIVES

Investigated the effect of no-stenosis (0% stenosis) and non-obstructive (0% < stenosis < 50%) on the prognostic impact of CMD in INOCA.

METHOD

A retrospective study assessed the coronary microvascular function in 151 INOCA patients who underwent invasive angiography by the coronary angiography-derived index of microcirculation-resistance (caIMR). CZT-SPECT was performed to evaluate myocardial perfusion imaging (MPI) abnormalities. Chi-square test/Fisher exact test, Student t-test, Kaplan-Meier curve, and Uni-multivariable Cox proportional models were used for analysis. Clinical outcomes were major adverse cardiovascular events (MACE) during a median follow-up of 35 months.

RESULT

No-stenosis was present in 71 (47%) INOCA patients, and 80 (53%) were with nonobstructive. CMD (caIMR ≥ 25) was more prevalent in patients with no-stenosis than nonobstructive (76.1% vs. 48.8%, p = .001), along with abnormal MPI (39.4% vs. 22.5%, p = .024). The MACE rates were not different between no-stenosis and nonobstructive stenosis. CMD showed an increased risk of MACE for all INOCA. No-stenosis with CMD had the worst prognosis. Cox regression analysis identified CMD and abnormal MPI as predictors of MACE in all INOCA and patients with no-stenosis. However, no-stenosis and nonobstructive stenosis were not predictors of MACE in INOCA.

CONCLUSION

CMD was more frequently present in INOCA with no-stenosis. However, there was no difference in long-term clinical outcomes between no-stenosis and nonobstructive stenosis. CMD could independently predict poor outcomes in INOCA, particularly in patients with no-stenosis.

Management of vasospastic angina

Vasospastic angina is a well-established cause of chest pain that is caused by coronary artery spasm. It can be clinically diagnosed during a spontaneous episode by documenting nitrate-responsive rest angina with associated transient ischaemic ECG changes but more often requires provocative coronary spasm testing with acetylcholine during coronary angiography. Vasospastic angina may result in recurrent episodes of angina (including nocturnal angina), which can progress on to major adverse cardiac events. Calcium channel blockers are first-line therapy for this condition, given their anti-anginal and cardioprotective benefits. Despite an established diagnostic and therapeutic management pathway for vasospastic angina, this diagnosis is often overlooked in patients presenting with chest pain. Thus, there is need for increased clinical awareness of vasospastic angina to improve outcomes in affected patients.

Myocardial infarction with non-obstructive coronary arteries in a patient double-seropositive for anti-glomerular basement membrane and anti-neutrophil cytoplasmic antibodies: A case report

We report a case of a patient double-seropositive for anti-glomerular basement membrane (anti-GBM) and anti-neutrophil cytoplasmic antibodies (ANCA) who reported retrosternal chest pain during a regular hemodialysis session associated with ST-segment depression in electrocardiogram and an increase of serum high-sensitivity troponin T. Urgent coronary angiography excluded obstructive coronary artery disease, suggesting the diagnosis of ischemia with non-obstructive coronary arteries. This case illustrates an unusual presentation of cardiovascular involvement in a patient with double-positive ANCA/anti-GBM disease, emphasizing the possible relevance of coronary microvascular dysfunction and the need for close cardiovascular follow-up in this patient population.

FT4/FT3 ratio: A novel biomarker predicts coronary microvascular dysfunction (CMD) in euthyroid INOCA patients

BACKGROUND

Ischemia and no obstructive coronary artery disease (INOCA) patients who presented coronary microvascular dysfunction (CMD) demonstrate a poor prognosis, yet the risk factors for CMD remain unclear. Subtle changes in thyroid hormone levels within the normal range, especially the free thyroxine (FT4)/free triiodothyronine (FT3) ratio, have been shown to regulate the cardiovascular system. This prospective study investigated the correlation between FT4/FT3 ratio and CMD in euthyroid patients with INOCA.

METHODS

This prospective study (www.chictr.org.cn/, ChiCTR2000037112) recruited patients with myocardial ischemia symptoms who underwent both coronary angiography (CAG) and myocardial perfusion imaging (MPI) with dynamic single-photon emission computed tomography (D-SPECT). INOCA was defined as coronary stenosis< 50% and CMD was defined as coronary flow reserve (CFR)<2.5. All patients were excluded from abnormal thyroid function and thyroid disease history.

RESULTS

Among 71 INOCA patients (15 [21.1%] CMD), FT4 and FT4/FT3 ratio in CMD group were significantly higher and both showed significantly moderate correlation with CFR (r=-0.25, p=0.03; r=-0.34, p=0.003, respectively). The ROC curve revealed that FT4/FT3 ratio had the highest efficacy for predicting CMD with an optimized cutoff value>3.39 (AUC 0.78, p<0.001, sensitivity, 80.0%; specificity, 71.4%). Multivariate logistic regression showed that FT4/FT3 ratio was an independent predictor of CMD (OR 7.62, 95% CI 1.12-51.89, p=0.038, P for trend=0.006).

CONCLUSION

In euthyroid INOCA patients, increased FT4/FT3 ratio levels are associated with the occurrence of CMD, presenting a novel biomarker for improving the risk stratification.