The relation between coronary flow rate, plasma endothelin-1 concentrations, and clinical characteristics in patients with normal coronary arteries

Anti-Anginal Efficacy of Zibotentan in the Coronary Slow-Flow Phenomenon

BACKGROUND

Patients with coronary microvascular disorders often experience recurrent angina for which there are limited evidence-based therapies. These patients have been found to exhibit increased plasma levels of endothelin; thus, selective endothelin-A (Et-A) receptor blockers such as zibotentan may be an effective anti-anginal therapy in these patients. The study evaluated the impact of a 10 mg daily dose of zibotentan on spontaneous angina episodes in patients with the coronary slow-flow phenomenon who had refractory angina (i.e., experiencing angina at least three times/week despite current anti-anginal therapy).

METHODS

Using a randomized, double-blind, placebo-controlled, crossover trial design with 4-week treatment periods, 18 patients (63.2 ± 9.9 years, 33% females) were recruited. The primary endpoint was angina frequency as measured by an angina diary, with secondary endpoints including nitrate consumption, angina duration/severity and the Seattle Angina Questionnaire (SAQ) domains.

RESULTS

During the 4 weeks of therapy, angina frequency significantly improved with zibotentan therapy (placebo 41.4 (58.5) vs. zibotentan 29.2 (31.6), p < 0.05), and sublingual nitrate consumption significantly reduced (placebo 11.8 (15.2) vs. zibotentan 8.8 (12.9), p < 0.05.

CONCLUSIONS

Zibotentan improved the frequency of spontaneous angina episodes and reduced sublingual nitrate consumption in patients unresponsive to standard anti-anginal therapy.

Evaluation of serum nitric oxide synthase levels in patients with coronary slow flow based on corrected TIMI frame count

Introduction

The coronary slow flow phenomenon (CSFP) finding in angiography is characterized by the delayed filling of the terminal vessels without significant epicardial coronary disease. The endothelium performs a vital role in cardiovascular homeostasis by releasing vasoactive substances. Endothelial cells produce nitric oxide (NO) as one of these essential compounds. Three isoforms of nitric oxide synthase (NOS) are endothelial nitric oxide synthase (eNOS), neuronal nitric oxide synthase (nNOS), and induced nitric oxide synthase (iNOS). We aimed to determine the role of NOS in the development of CSFP as the first human study.

Material and methods

A total of 129 patients who met the inclusion criteria were enrolled in the study. The patients were classified into five groups based on the results of coronary angiography: Group 1 without coronary artery disease (CAD) and without CSF, group 2 without CAD and with CSF, group 3 with CAD (< 50%) and without CSF, group 4 with CAD (50-90%) and without CSF, and group 5 with CAD and CSF. The serum level of NOS was determined in the participants. Coronary flow was quantified in patients with CSFP using the corrected TIMI frame count (CTFC) method, and the correlation between the levels of this biomarker and CTFC was investigated.

Results

In this study, the NOS serum levels were not significantly correlated with the mean CTFC. Since the total amount of NOS was measured as a result of 3 isoforms of this enzyme, the lack of correlation could be related to increased iNOS level and decreased eNOS concentration.

Conclusions

These results should be confirmed by more human studies.

Echocardiographic and laboratory findings in coronary slow flow phenomenon: cross-sectional study and review

Background

Coronary sow-flow phenomenon (CSFP) is defined as slow passage of the contrast injected into the coronary arteries without distal obstruction of the vessel.

Methods

The present study was a cross-sectional, descriptive-analytical study performed at the Seyed-al-Shohada Heart Center during 2018–2019. The eligible patients based on the inclusion and exclusion criteria were divided into the study group showing the CSFP and the control group with normal epicardial coronary arteries.

Results

The study included 124 patients. 67.9% of the study group and 39.4% of the control group were male patients (p-value = 0.001), and the mean patient age was 52.18 ± 12.55 and 51.77 ± 10.36 years in the study and control groups, respectively (p-value = 0.18). The study group had a significantly higher BMI than the control group (p < 0.05) and also a higher prevalence of smoking and hypertension. The variables of ALC, Hct, Plt, MPV, RDW, Cr, triglyceride, TC, and LDL, were higher in the study group. Given the echocardiographic findings, the mean E wave was significantly lower in the study group, while the control group had a significantly higher GLS (p-value = 0.01). Also, left anterior descending artery was the most common artery involved with CSFP.

Conclusion

The CSFP was significantly more common in men, smokers, hypertensive patients, and patients with high BMI. Moreover, these patients had significantly higher platelet count, MPV, LDL, and FBS. Some other laboratory variables were also higher in these patients. Given the echocardiographic findings, mild diastolic dysfunction and low GLS were also observed in the study group.

Performance of neutrophil to lymphocyte ratio for the prediction of long-term morbidity and mortality in coronary slow flow phenomenon patients presented with non-ST segment elevation acute coronary syndrome

Introduction: In this study, we aimed to determine if neutrophil to lymphocyte ratio could predict long term morbidity and mortality in patients who hospitalized for non-ST segment elevation acute coronary syndrome (NSTE-ACS) and had coronary slow flow on coronary angiography.

Methods: In this observational study, 111 patients who presented with NSTE-ACS and diagnosed with coronary slow flow phenomenon on angiographic examination were included. Neutrophil to lymphocyte ratio (NLR) calculated as the ratio of the number of neutrophils to the number of lymphocytes. Patients classified into three groups according to NLR values. The term coronary slow flow phenomenon was depicted by calculating Thrombolysis in Myocardial Infarction frame count.Patients were followed up and the occurrence of recurrent angina, recurrent myocardial infarction, and long-term mortality was determined using medical records, phone calls, or face-to-face interviews. P values <0.05 considered to indicate statistical significance.

Results: Recurrent angina and myocardial infarction occurred more frequently in the highest NLR tertile compared with middle and lowest NLR tertiles. High NLR group (NLR≥ 3.88 n=38) was significantly associated with younger age and smoking status. WBC, troponin I and CRP levels increased as the NLR tertile increased. Recurrent myocardial infarction and angina showed strong relationship with increasing NLR values. In multivariate regression analyses smoking and high NLR levels were independent predictors of recurrent myocardial infarction (HR:4.64 95%CI 0.95-22.52 P=0.04, HR: 1.48 95%CI 1.16-1.90 P<0.01 respectively) in the long term follow up.

Conclusion: Our study demonstrated that high NLR values can be a valuable prognostic tool in the long term follow up of patients who presented with NSTE-ACS and diagnosed with slow flow phenomenon on coronary angiography.

Evaluation of the Correlation between Serum Concentrations of Asymmetric Dimethylarginine and Corrected TIMI Frame Count in Patients with Slow Coronary Flow

Coronary slow flow (CSF) is an important angiographic entity that is characterized by delayed opacification of coronary arteries in the absence of epicardial occlusive disease. Asymmetric dimethylarginine (ADMA) is an endogenous inhibitor of nitric oxide synthase. Elevated levels of ADMA cause the induction of endothelial dysfunction and thus promote atherosclerosis. This study was aimed at determining the role of ADMA in the development of CSF. One hundred twenty-nine subjects who fulfilled the inclusion criteria were enrolled in this study. According to coronary angiography results, these subjects were divided into five groups. The serum concentration of ADMA was measured in these subjects. In this study, there was no significant correlation between serum concentrations of ADMA and mean corrected TIMI frame count (CTFC) (P > 0.05). However, the ADMA level was significantly correlated with CTFC in the left anterior descending (LAD) coronary artery in patients with CSF (r = −0.381, P = 0.045). Also, plasma ADMA levels were significantly higher in patients with CSF and without CAD compared to patients without CSF and with CAD (50-90%) (P = 0.034). Besides, serum concentrations of ADMA were significantly higher in subjects with BMI < 25 kg/m² compared with those having BMI > 30 kg/m² (P = 0.003). It was also shown that the levels of ADMA were significantly higher in subjects with age as a cardiovascular risk factor compared with those without this risk factor (P = 0.024). Further studies with larger population sizes are needed to confirm the present findings on the association between the serum concentrations of ADMA and CSF.

Ventricular Dysfunction in Patients with Coronary Slow-Flow Phenomenon: A Single-center Case-control Study

Background:

Coronary slow-flow phenomenon (CSFP), characterized by delayed distal vessel opacification of contrast, in the absence of significant epicardial coronary stenosis, has effects on exercise capacity and clinical outcomes. The aim of this study was to explore the systolic and diastolic function of patients with CSFP and to compare it with a group of controls with normal coronary anatomy and flow.

Materials and Methods:

In this case–control study, 45 consecutive CSFP patients and 45 age-, body mass index-, and presentation season-matched controls with normal coronary arteries and normal coronary flows were enrolled from Seyyedoshohada Heart Center from March 2015 to March 2016. A transthoracic echocardiography was done by a blinded echocardiographer using both conventional and tissue Doppler imaging techniques.

Results:

Patients with CSFP were more likely to be male (P = 0.006) and smoker (P = 0.02) compared to controls. Other risk factors were not different between the two groups. There were no differences between groups in terms of the peak early (E) and late (A) diastolic velocities, deceleration time, early (E’) and late (A’) peak diastolic velocities at the mitral annulus, and the systolic mitral annular velocity (S’). Global longitudinal strain and peak systolic strain rates was lower in patients with CSFP compared to controls (−16.7% ±2.4% vs. −18.9% ±1.6%, P < 0.001 and 1.10 ± 0.1 vs. 1.24 ± 0.3, P = 0.008, respectively).

Conclusion:

Patients with CSFP showed signs of the left ventricular systolic dysfunction in tissue Doppler echocardiography, which underlines the importance of close follow-up in these patients. Patients with CSFP should be screened for ventricular function preferably by tissue Doppler echocardiography.

Statistical analysis plan for "A randomised, controlled study to evaluate the effects of switching from cigarette smoking to using a tobacco heating product on health effect indicators in healthy subjects"

Tobacco harm reduction strategies aim to substitute smoking with potentially reduced risk products (PRRPs) such as e-cigarettes and tobacco-heating products (THPs). The health benefits of switching from smoking to PRRPs is unknown. A randomised controlled trial is being conducted to increase understanding of the health effects of switching from smoking to a THP in a 12-month long ambulatory study (ISRCTN81075760). Here we describe the study endpoints and the statistical analysis plan. Endpoints are divided into biomarkers of exposure (BoE) to tobacco smoke constituents and health effect indicators related to risk of lung cancer, cardiovascular and obstructive lung disease. These have been selected on the basis of extensive literature evidence. Three primary endpoints, augmentation index (risk factor for cardiovascular disease), total NNAL (linked to lung cancer) and 8-Epi-PGF2α type III (indicator of oxidative stress linked to various diseases), and multiple secondary endpoints will be analysed at 90, 180, and 360 days. Changes from baseline will be compared between study arms by specific contrasts in mixed models. Study wise multiple comparisons adjustments will be performed to account for multiplicity of timepoints and comparisons within timepoints. Generalisability of outcomes will be tested by a sensitivity analysis adjusting for age and gender. Importantly, an ancillary analysis will be performed to assess product compliance during the study based on plasma levels of CEVal, a surrogate marker for acrylonitrile exposure. The rationale underlying the selection of BoEs and health effect indicators, coupled with the statistical analysis plan will be central to understanding the potential health effects of replacing smoking with THP use for one year.

Plasma Choline as a Diagnostic Biomarker in Slow Coronary Flow

Aim

The slow coronary flow (SCF) phenomenon was characterized by delayed perfusion of epicardial arteries, and no obvious coronary artery lesion in coronary angiography. The prognosis of patients with slow coronary flow was poor. However, there is lack of rapid, simple, and accurate method for SCF diagnosis. This study aimed to explore the utility of plasma choline as a diagnostic biomarker for SCF.

Methods

Patients with coronary artery stenosis <40% evaluated by the coronary angiogram method were recruited in this study and were grouped into normal coronary flow (NCF) and SCF by thrombolysis in myocardial infarction frame count (TFC). Plasma choline concentrations of patients with NCF and SCF were quantified by Ultra Performance Liquid Chromatography Tandem Mass Spectrometry. Correlation analysis was performed between plasma choline concentration and TFC. Receiver operating characteristic (ROC) curve analysis with or without confounding factor adjustment was applied to predict the diagnostic power of plasma choline in SCF.

Results

Forty-four patients with SCF and 21 patients with NCF were included in this study. TFC in LAD, LCX, and RCA and mean TFC were significantly higher in patients with SCF in comparison with patients with NCF (32.67 ± 8.37 vs. 20.66 ± 3.41, P  <  0.01). Plasma choline level was obviously higher in patients with SCF when compared with patients with NCF (754.65 ± 238.18 vs. 635.79 ± 108.25, P=0.007). Plasma choline level had significantly positive correlation with Mean TFC (r = 0.364, P=0.002). Receiver operating characteristic (ROC) analysis showed that choline with or without confounding factor adjustment had an AUC score of 0.65 and 0.77, respectively.

Conclusions

TFC were closely related with plasma choline level, and plasma choline can be a suitable and stable diagnostic biomarker for SCF.

Association between impaired cutaneous microvascular endothelial function and lectin-like oxidized low-density lipoprotein receptor-1 in patients with coronary slow flow

OBJECTIVE

Although increasing studies indicate coronary slow flow (CSF) is a systemic microvascular disorder, whether there is impaired cutaneous microvascular endothelial function in CSF patients remains unclear. This study was designed to test the hypothesis that the cutaneous microvascular endothelial function of CSF patients is impaired and correlates with lectin-like oxidized low-density lipoprotein receptor-1(LOX-1).

METHODS

39 patients with CSF and 45 controls with normal coronary flow were enrolled. Velocity of coronary flow was quantitatively identified by thrombolysis in myocardial infarction frame count (TFC) method. LSCI system was used to assess subjects' cutaneous blood flow at rest and during PORH. Serum soluble LOX-1(sLOX-1) level was measured in all study subjects.

RESULTS

PORH-induced vasodilation was significantly reduced in CSF group in comparison with control group (0.26 ± 0.10 vs 0.35 ± 0.07 APU/mmHg, P < 0.001) and negatively correlated with the mean TFC for three coronary arteries (r = -0.385, P = 0.016). Serum sLOX-1 level in CSF group was significantly increased (582.93 ± 74.89 vs 483.64 ± 51.38 pg/ml, P < 0.001) and positively correlated with mean TFC(r = 0.467, P = 0.003).PORH response amplitudes had a significantly negative relationship with serum sLOX-1 level in CSF patients (r = -0.588, P < 0.001).

CONCLUSION

These data suggest that cutaneous microvascular endothelial function is impaired in patients with CSF, which is closely associated with increased LOX-1 expression.

Evaluation of homocysteine in the diagnosis and prognosis of coronary slow flow syndrome

Aim: To identify the exact molecular markers related to coronary slow flow syndrome (CSFS) and its prognosis. Patients & methods: Data from 54 patients with CSFS diagnosed by coronary angiography and 101 normal control patients were collected and analyzed. Results: Logistic regression analysis confirmed that homocysteine (Hcy; odds ratio: 1.107; 95% CI: 1.018-1.205; p = 0.018) was associated with CSFS. Receiver-operating characteristic curve analysis identified an Hcy value of 17.1 μmol/l as an effective cut-off point for predicting CSFS. Cox survival analysis showed a relationship between high admission Hcy level (odds ratio: 1.19; 95% CI = 1.05-1.34; p = 0.005) and recurrent angina. Conclusion: Our results showed positive correlations of Hcy with CSFS and cardiac events.

Nicorandil improves myocardial function by regulating plasma nitric oxide and endothelin-1 in coronary slow flow

BACKGROUND

Coronary slow flow (CSF) is a special coronary microvascular disorder. The pathogenesis and effective therapeutics of CSF remain unclear. This study aimed to evaluate the global and regional functions of the left ventricle (LV) and investigate the efficacy of nicorandil in patients with CSF.

PATIENTS AND METHODS

Thirty-six patients with CSF in the left anterior descending (LAD) branch and 20 patients with normal coronary arteries were included. Global and regional functions of the LV supplied by LAD were measured using conventional Doppler echocardiography and two-dimensional speckle tracking echocardiography, respectively, within 24 h after coronary angiography. Concentrations of plasma nitric oxide (NO) and endothelin-1 (ET-1) were detected using colorimetry and radioimmunoassay, respectively. The function of the LV and the levels of NO and ET-1 were also investigated before and 90 days after treatment with 15 mg/day of nicorandil.

RESULTS

Compared with the control group, the early diastolic peak velocity (E), E/A ratio, and plasma NO levels were lower, whereas the late diastolic peak flow velocity (A) and plasma ET-1 levels were significantly higher in the CSF group (P<0.05). The longitudinal strain rate peak of the LV was reduced significantly in CSF patients (P<0.001). After treatment, 75% (27/36) of CSF patients were free of chest pain. The values of E peak, E/A ratio, longitudinal strain rate peak, and plasma NO level were increased (P<0.001), whereas the ET-1 level was decreased in CSF patients (P<0.001).

CONCLUSION

Nicorandil may improve chest pain symptoms and the impaired function of the LV, possibly by increasing plasma NO and reducing ET-1 in CSF.

Assessment of left and right ventricular diastolic and systolic functions using two-dimensional speckle-tracking echocardiography in patients with coronary slow-flow phenomenon

OBJECTIVE

Coronary slow-flow phenomenon (CSFP) is an angiographic diagnosis characterised by a low rate of flow of contrast agent in the normal or near-normal epicardial coronary arteries. Many of the patients with CSFP may experience recurrent acute coronary syndromes. However, current clinical practice tends to underestimate the impact of CSFP due to the yet unknown effect on the cardiac function. This study was performed to evaluate left ventricular (LV) and right ventricular (RV) diastolic and systolic functions, using two-dimensional (2D) longitudinal strain and strain rate, in patients with CSFP, and to determine the relationships between the thrombolysis in myocardial infarction (TIMI) frame count (TFC) and LV and RV diastolic and systolic functions.

METHODS

Sixty-three patients with CSFP and 45 age- and sex-matched controls without CSFP were enrolled in the study. Diagnosis of CSFP was made by TFC. LV and RV diastolic and systolic functions were assessed by 2D speckle-tracking echocardiography.

RESULTS

LV peak early diastolic longitudinal strain rate (LSRe) was lower in patients with CSFP than in controls (P = 0.01). LV peak systolic longitudinal strain (LS) and LV peak systolic longitudinal strain rate (LSRs) were lower in patients with CSFP than in controls (P = 0.004 and P = 0.03, respectively). There was no difference in LV ejection fraction. RV peak early diastolic longitudinal strain rate (RSRe) was lower in patients with CSFP than in controls (P = 0.03). There were no differences in RV peak systolic longitudinal strain (RS), RV peak systolic longitudinal strain rate (RSRs), or RV fractional area change among the groups. The mean TFC correlated negatively with LSRe and RSRe in patients with CSFP (r = -0.26, P = 0.04 and r = -0.32, P = 0.01, respectively).

CONCLUSIONS

LV diastolic and systolic functions were impaired in patients with CSFP. CSFP also affected RV diastolic function, but not RV systolic function.

The relationship between coronary slow flow phenomenon and urotensin-II: A prospective and controlled study

OBJECTIVE

The underlying mechanism of coronary slow flow (CSF) has not yet been clarified, although many studies have been conducted to understand its pathophysiology. In this study, we investigated the role of a very potent vasoconstrictor, urotensin-II (UII), in the pathophysiology of CSF. This prospective and controlled investigation aimed to evaluate the association between CSF and serum levels of UII.

METHODS

Our study included 32 patients with slow flow in any coronary artery and 32 patients with normal coronary arteries. Coronary flow was calculated using the Thrombolysis in Myocardial Infarction (TIMI) frame count (TFC) method, and CSF was defined as TFC ≥39 for the left anterior descending artery, TFC ≥27 for the circumflex coronary artery, and TFC ≥24 for the right coronary artery. UII levels in blood samples obtained from both groups were measured by enzyme-linked immunosorbent assay (ELISA) method.

RESULTS

UII levels were significantly higher in the CSF group than in the control group [122 pg/mL (71-831), 95 pg/mL (21-635), respectively; p<0.001]. High-density lipoprotein (HDL) levels were lower in the CSF group, and leukocyte counts were significantly higher. A positive correlation between UII and mean TFC (r=0.524, p=0.002) was found in the CSF group. The multivariate logistic regression analysis determined that UII, HDL, and cigarette smoking were independent indicators in predicting CSF (OR=1.010, 95% confidence interval 1.002-1014, p=0.019; OR=0.927, 95% confidence interval 0.869-0.988, p=0.019; OR=5.755, 95% confidence interval 1.272-26.041, p=0.021, respectively).

CONCLUSION

Serum UII levels were found to be significantly higher in the CSF group, suggesting that UII may be one of the underlying factors in the pathogenesis of CSF.

Working under pressure: coronary arteries and the endothelin system

Endogenous endothelin-1-dependent (ET-1) tone in coronary arteries depends on the balance between ET(A) and ET(B) receptor-mediated effects and on parameters such as receptor distribution and endothelial integrity. Numerous studies highlight the striking functional interactions that exist between nitric oxide (NO) and ET-1 in the regulation of vascular tone. Many of the cardiovascular complications associated with cardiovascular risk factors and aging are initially attributable, at least in part, to endothelial dysfunction characterized by a dysregulation between NO and ET-1. The contribution of the imbalance between smooth muscle ET(A/B) and endothelial ET(B) receptors to this process is poorly understood. An increased contribution of ET-1 that is associated with a proportional decrease in that of NO accompanies the development of coronary endothelial dysfunction, coronary vasospasm, and atherosclerosis. These data form the basis for the rationale of testing therapeutic approaches counteracting ET-1-induced cardiovascular dysfunction. It remains to be determined whether the beneficial role of endothelial ET(B) receptors declines with age and risk factors for cardiovascular diseases, revealing smooth muscle ET(B) receptors with proconstricting and proinflammatory activities.

Endothelium-derived endothelin-1

One year after the revelation by Dr. Furchgott in 1980 that the endothelium was obligatory for acetylcholine to relax isolated arteries, it was clearly shown that the endothelium could also promote contraction. In 1988, Dr. Yanagisawa's group identified endothelin-1 (ET-1) as the first endothelium-derived contracting factor. The circulating levels of this short (21-amino acid) peptide were quickly determined in humans, and it was reported that, in most cardiovascular diseases, circulating levels of ET-1 were increased, and ET-1 was then tagged as "a bad guy." The discovery of two receptor subtypes in 1990, ET(A) and ET(B), permitted optimization of the first dual ET-1 receptor antagonist in 1993 by Dr. Clozel's team, who entered clinical development with bosentan, which was offered to patients with pulmonary arterial hypertension in 2001. The revelation of Dr. Furchgott opened a Pandora's box with ET-1 as one of the actors. In this brief review, we will discuss the physiological and pathophysiological role of endothelium-derived ET-1 focusing on the regulation of the vascular tone, and as much as possible in humans. The coronary bed will be used as a running example in this review because it is the most susceptible to endothelial dysfunction, but references to the cerebral and renal circulation will also be made. Many of the cardiovascular complications associated with aging and cardiovascular risk factors are initially attributable, at least in part, to endothelial dysfunction, particularly dysregulation of the vascular function associated with an imbalance in the close interdependence of nitric oxide and ET-1.