The relationship between plasma endothelin-1, nitric oxide levels, and heart rate variability in patients with coronary slow flow

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.

Comparison of subfoveal choroidal thickness and retinal nerve fiber layer thickness in patients with coronary slow flow phenomenon and microvascular angina: Optical coherence tomography based study

BACKGROUND

The aim of this study was to evaluate and compare the subfoveal choroidal thickness (SFCT) and peripapillary retinal nerve fiber layer thickness (pRNFLT) in patients with microvascular angina (MA), coronary slow flow phenomenon (CSFP) and healthy controls.

METHODS

Thirty-two consecutive patients with MA, 35 consecutive patients with CSFP and 40 age and sex-matched controls were enrolled. SFCT, average pRNFLT and four quadrants of pRNFLT were measured by spectral domain- optical coherence tomography (SD-OCT).

RESULTS

The mean SCFT in patients with CSFP (267.57 ± 30.61 μm) was significantly thinner than those of patients with MA (288.84 ± 28.25 μm) and control (291.21 ± 31.75 μm) (p = 0.002) while SFCT of patients with MA were similar with those of controls. Patients with CSFP had thinner superior and inferior pRNFLT compared to patients with MA and controls (p < 0.001 and p = 0.005, respectively) while there were no significant differences in average pRNFLT, nasal and temporal quadrant of pRNFLTs among three groups. In the multivariate linear regression analyses, the presence of CSFP was found negatively correlated with SFCT and superior pRNFLT.

CONCLUSION

Patients with CSFP had thinner SFCT, superior and inferior quadrants of pRNFLT proposing the presence of a generalized endothelial dysfunction and increased microvascular resistance in these patients.

Beetroot juice intake with different amounts of nitrate does not change aerobic exercise-mediated responses in heart rate variability in hypertensive postmenopausal women: A randomized, crossover and double-blind study

Objectives

To compare the acute effects of a single dose of beetroot juice (BJ) with different concentrations of nitrate (NO₃⁻) on heart rate variability (HRV) in postmenopausal hypertensive women.

Methods

Thirteen hypertensive postmenopausal women (58.1 ± 4.6 years of age and 27 ± 4 kg/m² of BMI) completed the protocol that consisted of three visits with different beverage intakes in a randomized and crossover design. The three beverages were BJ with a high content of nitrate (high-NO₃^-), BJ with a low content of nitrate (low-NO₃^-), and an orange flavored non-caloric drink (OFD). Heart rate (HR) were evaluated during 20 min after sitting rest at 7:20 a.m. (baseline), after they drank one of the drinks, and remained at sitting rest for 120 min and then performed 40 min of aerobic exercise at 65–70% of the HR reserve on a treadmill. HR was recorded for 90 min after exercise for time, frequency, and non-linear domains of HRV index analysis.

Results

Two-way ANOVA showed that there were no interaction effects (time∗sessions) in any of the HRV indexes after exercise in all three sessions. HRV indexes increased after exercise (p = <0.05) similarly in all three sessions when compared with the baseline time point.

Conclusion

Therefore, a single dose of BJ, independent of NO₃⁻ content, does not change aerobic exercise-mediated responses in HRV indexes in hypertensive postmenopausal women.

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.

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.

Effect of Coronary Slow Flow on Intrinsicoid Deflection of QRS Complex

Coronary slow flow is a rare, clinically important entity observed in acute coronary syndrome. The pathophysiological mechanism is not fully elucidated. We investigated patients with chest pain who had angiographic features consistent with the coronary slow flow. One hundred ten patients were included. Electrocardiography, echocardiography, and angiography results were retrospectively noted. The mean age was 56.4. Fifty-eight were male, and fifty-two were female. The control group consisted of patients with normal angiography. Patients had higher diastolic blood pressure, lower mean ejection fraction, higher average left ventricular end-diastolic diameter, and higher mean left atrial size than the control group (p=0.009, p=0.017, p=0.041, andp < 0.001, resp.). Patients had higher average V1 ID, V6 ID, P wave dispersion, TFC LAD, TFC Cx, TFC RCA, and TFC levels than the control group. A significant linear positive relationship was found between the V1 ID and the TFC LAD, TFC Cx, TFC RCA, and TFC; also between the V6 ID and the TFC LAD, TFC Cx, TFC RCA, and TFC. Angiographic and electrocardiographic features are suggestive and diagnostic for the coronary slow flow syndrome. Although when regarded as a benign condition, coronary slow flow should be diagnosed, followed up, and treated as many of laboratory features suggest ischemic events.

Association of Interleukin-1 Gene cluster polymorphisms with coronary slow flow phenomenon

Objective:

Coronary slow flow phenomenon (CSFP) is characterized by the decreased rate of contrast progression in epicardial coronary arte-ries in the absence of significant coronary stenosis. Mounting evidence has showed a significant association between inflammation and CSFP severity. This study aimed to evaluate possible associations between interleukin-1 receptor antagonist (IL-1ra) gene variable number tandem repeat (VNTR), IL-1β -511 single nucleotide (SNP), and IL-1β+3954 SNP mutations with CSFP.

Methods:

Forty-eight patients with CSFP and 62 controls with angiographically normal coronary arteries were prospectively enrolled in the study. Genotypes were assessed using the polymerase chain reaction (PCR)-based restriction fragment length polymorphism (PCR-RFLP) technique.

Results:

Homozygote genotype for allele 2 of+3954 C>T 2/2 genotype was significantly more frequent in patients with CSFP than in the control group, whereas 1/2 genotype was more frequent in the control group (35.4% versus 14.5% for 2/2 genotype and 25% versus 35.5% for 1/2 genotype in CSFP and control groups, respectively, X²=6.6; p=0.04). The allelic frequency of allele 2 of this polymorphism was significantly higher in the CSFP group than in the control group (47.9% versus 28.6% in the control group, X²=5.6; p=0.02). However, there was no significant difference with regard to genotype or allelic frequencies of IL-1ra VNTR or IL-1β -511 SNP polymorphisms between patients with CSFP and controls.

Conclusion:

IL-1β+3954 SNP mutations are significantly more common in patients with CSFP. It may suggest that the tendency for inflammation may contribute to the presence of this phenomenon.

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.

Endothelial nitric oxide synthase levels and their response to exercise in patients with slow coronary flow

Background

Endothelial dysfunction plays a key role in the aetiopathogenesis of slow coronary flow (SCF) even if there is no obstructive epicardial lesion. Reduced plasma levels of endothelial nitric oxide synthase (eNOS) are an important indicator of endothelial dysfunction. We aimed to determine plasma levels of eNOS and their relationship with exercise in patients with SCF.

Methods

Twenty-two patients with SCF in at least one coronary artery and 17 healthy individuals were included in this study. The TIMI frame count method was used to determine SCF. Plasma levels of eNOS before and after effort were determined in the patient and control groups.

Results

Basal eNOS levels in the patient group were lower than in the control group (p = 0.040), and plasma eNOS levels after exercise decreased more significantly in the patient group compared to the control group (p = 0.002). Median decreases of eNOS in response to exercise were higher in the SCF group than in the control group (p < 0.001), and the decrease observed in the control group was not statistically significant (p = 0.35). There were significantly negative correlations between TIMI frame count and plasma levels of eNOS at baseline and after exercise (r = –0.51, p = 0.015, r = –0.58, p = 0.005, respectively). Moreover, there was also a positive correlation between the rate–pressure product and plasma levels of eNOS after exercise in patients with SCF (r = 0.494, p = 0.019).

Conclusion

Our findings indicate an important pathophysiological relationship between the severity of SCF in which endothelial dysfunction plays a role in its pathogenesis and the level of circulating plasma levels of eNOS.

Effects of Nitrate Supplementation on Cardiovascular and Autonomic Reactivity in African-American Females

Previous studies have shown that beetroot juice (BJ) decreases systolic blood pressure (SBP) and oxygen demand. This study tests the hypothesis that a beetroot juice (BJ) treatment increases heart rate variability (HRV) measured by the average standard deviation of normal-normal electrocardiogram RR intervals (SDNN) and the low frequency (LF), mainly sympathetic, fast Fourier transform spectral index of HRV. The subjects were 13 healthy young adult African-American females. Placebo control orange juice (OJ) and BJ treatments were given on separate days. Blood nitric oxide [NO], SBP and RR intervals were measured at rest and at constant workloads set to 40% and 80% of the predetermined VO_2peak. Two hours after ingestion the BJ treatment increased [NO] and decreased SBP. BJ also increased SDNN at rest and at the 40% VO_2peak workload, without significant effects on LF. SDNN was significantly greater after the BJ than after the OJ treatment, across the two physical activity conditions and SDNN was (negatively) correlated with SBP. These results suggest that BJ decreases SBP and increases HRV at rest and during aerobic exercise. Similar results in subjects with prehypertension or hypertension could translate to a dietary nitrate treatment for hypertension.

Endothelial dysfunction in patients with noncomplicated and complicated hypertension

Endothelial dysfunction plays an important role in the pathogenesis of hypertension. Other risk factors of atherosclerosis also affect its development. The aim of the study was to assess nitric oxide metabolites concentration (nitrites and nitrates No(x)) and endothelin (ET-1) in plasma and cyclic 3,5-guanosine monophosphate (cGMP) in 24 h-urine collection in patients with noncomplicated hypertension without risk factors of atherosclerosis and in hypertensive patients with coronary artery disease (CAD). Sixty-eight subjects were included in the study (44 men, 24 women), aged 47 +/- 76 years, allotted into four groups: I - controls (18 clinically healthy subjects); II - 12 subjects with hypertension without risk factors of atherosclerosis; III - 16 subjects with hypertension and risk factors of atherosclerosis; and IV - 22 subjects with hypertension and CAD. Plasma NO(x) concentration was determined using the Greiss method, plasma ET-1 by ELISA, and urine cGMP using the immunoenzymatic method. Plasma NO(x) concentration was 14.00 +/- 6.88 micromol/L in group I, in group II - 18.62 +/- 5.84 micromol, in group III - 9.96 +/- 4.72 micromol/L, and in group IV - 8.78 +/- 3.72 micromol/L. Statistically significant differences were between groups I and III (p < 0.05) and I and IV (p < 0.04) and groups II and III (p < 0.01) and II and IV (p < 0.01). The concentration of cGMP in 24 h urine collection was in group I - 40 +/- 24 pmol/L; in group II - 54 +/- 41 pmol/L; in group III - 38 +/- 32 pmol/L; and in group IV - 42 +/- 36 pmol/L. There were no significant differences between the groups. Plasma ET-1 concentration was 3.86 +/- 0.52 pg/mL in group I, in group II - 4.05 +/- 0.71 pg/mL, in group III - 4.22 +/- 0.79 pg/mL and in group IV - 4.38 +/- 0.75 pg/mL. Statistically significant differences were between group I and III (p < 0.05), I and IV (p < 0.03), and between group II and IV (p < 0.04). Endothelial dysfunction was not found in hypertensive patients without a family history of cardiovascular diseases and without other risk factors of atherosclerosis. Deterioration of endothelial function was observed in patients with hypertension with risk factors of atherosclerosis. It was most pronounced in those with CAD.

Use of the TIMI frame count in the assessment of coronary artery blood flow and microvascular function over the past 15 years

Since its introduction, the TIMI frame count method has contributed to the understanding of the pathophysiology of coronary artery disease. In this article, the evolution of the TFC method and its applicability in the assessment of various therapeutic modalities are described.

Evaluation of eplerenone in the subgroup of EPHESUS patients with baseline left ventricular ejection fraction ≤30%

AIMS

Because of the prognostic importance of LV dysfunction following an AMI and the increasing use of electrical and/or mechanical interventions in patients with LV systolic dysfunction, this retrospective analysis of EPHESUS patients with LVEF <or=30% at baseline was conducted to determine the value of eplerenone in this setting.

METHODS AND RESULTS

In EPHESUS, 6,632 patients with LVEF <or=40% and clinical heart failure (HF) post-AMI who were receiving standard therapy were randomized to eplerenone 25 mg/day titrated to 50 mg/day or placebo for a mean follow-up of 16 months. Treatment with eplerenone in the subgroup of patients with LVEF <or=30% (N=2106) resulted in relative risk reductions of 21% versus placebo in both all-cause mortality (P=0.012) and cardiovascular (CV) mortality/CV hospitalization (P=0.001), and 23% for CV mortality (P=0.008). The relative risk of sudden cardiac death (SCD) was reduced 33% (P=0.01) and HF mortality/HF hospitalization was reduced 25% (P=0.005) with eplerenone compared with placebo. Within 30 days of randomization, eplerenone resulted in relative risk reductions of 43% for all-cause mortality (P=0.002), 29% for CV mortality/CV hospitalization (P=0.006), and 58% for SCD (P=0.008).

CONCLUSIONS

Treatment with eplerenone plus standard therapy in patients with post-AMI HF and LVEF <or=30% provided significant incremental benefits in reducing both early and late mortality and morbidity.

The effects of trimetazidine on heart rate variability in patients with slow coronary artery flow

OBJECTIVE

We sought to examine the effect of trimetazidine (TMZ) on heart rate variability (HRV), endothelin-1 (ET-1), NO, and anginal symptoms in patients with slow coronary artery flow (SCAF).

METHODS

The 48 patients with SCAF (29 women and 19 men; mean age, 52 +/- 9 years) were included in the study. Twenty milligrams TMZ 3 times a day or matched placebo were given randomly in a double-blinded fashion for 4 weeks. Patients were divided into 4 groups as follows: exercise-positive, TMZ-given group (group A, n = 12); exercise-positive, placebo-given group (group B, n = 12); exercise-negative, TMZ-given group (group C, n = 12); and exercise-negative, placebo-given group (group D, n = 12).

RESULTS

After TMZ treatment, HRV parameters, including SD of the all R-R intervals, SD of the averages of R-R intervals in all 5-minute segments of the entire recording, percentage of R-R intervals with more than 50-millisecond variation, and the square root of the mean of the sum of the squares of differences between adjacent R-R intervals, significantly improved both in exercise-positive and exercise-negative groups when compared with baseline. After TMZ treatment, ET-1 and NO levels significantly altered both in exercise-positive and exercise-negative groups when compared with baseline (17.7 +/- 2.7 vs 13.9 +/- 2.8 pg/mL [P = .01] and 18.1 +/- 3.8 vs 14.2 +/- 2.6 pg/mL [P = .01], respectively). After TMZ treatment, NO levels significantly increased in both exercise-positive and exercise-negative groups when compared with baseline (36.4 +/- 5.4 vs 43.3 +/- 6.8 micromol/L [P = .01] and 36.8 +/- 7.8 vs 43.3 +/- 4.8 micromol/L [P = .01], respectively). However, in placebo group, neither HRV parameters nor ET-1 and NO levels altered when compared with baseline. Also, after treatment, a significant correlation was detected between HRV parameters, including SD of the averages of R-R intervals in all 5-minute segments of the entire recording, SD of the all R-R intervals, percentage of R-R intervals with more than 50-millisecond variation, and the square root of the mean of the sum of the squares of differences between adjacent R-R intervals, and NO and ET-1 levels in TMZ group but not placebo.

CONCLUSION

Short-term TMZ therapy improved HRV parameters and endothelial products such as ET-1 and NO as well as anginal symptom in patients with SCAF. Improvement in HRV parameters was correlated with ET-1 and NO levels.

Differential regulation of the lung endothelin system by urban particulate matter and ozone

Periodic elevation of ambient particulate matter and ozone levels is linked to acute cardiac morbidity and mortality. Increased plasma levels of the potent vasoconstrictor endothelin (ET)-1, a prognostic indicator of cardiac mortality, have been detected in both animal models and humans after exposure to air pollutants. The lungs are the primary source of circulating ET-1, but the direct effects of individual air pollutants and their interaction in modulating the pulmonary endothelin system are unknown. Fischer-344 rats were exposed to particles (0, 5, 50 mg/m3 EHC-93), ozone (0, 0.4, 0.8 ppm), or combinations of particles and ozone for 4 h. Changes in gene expression were measured using real-time reverse transcription polymerase chain reaction immediately after exposure and following 24 h recovery in clean air. Both pollutants individually increased preproET-1, endothelin converting enzyme-1, and endothelial nitric oxide synthase mRNA levels in the lungs shortly after exposure, consistent with the concomitant increase in plasma of the 21 amino acid ET-1[1-21] peptide measured by HPLC-fluorescence. PreproET-1 mRNA remained elevated 24 h after exposure to particles but not after ozone, in line with previously documented changes of the peptide in plasma. Both pollutants transiently increased endothelin-B receptor mRNA expression, while ozone decreased endothelin-A receptor mRNA levels. Coexposure to particles plus ozone increased lung preproET-1 mRNA but not plasma ET-1[1-21], suggesting alternative processing or degradation of endothelins. This coincided with an increase in the lungs of matrix metalloproteinase-2 (MMP-2), an enzyme that cleaves bigET-1 to ET-1[1-32]. Taken together, our data indicate that ozone and particulate matter independently regulate the expression of lung endothelin system genes, but show complex toxicological interaction with respect to plasma ET-1.