Objective: The aim of our research was to evaluate the relationship involving left ventricular ejection fraction, low density lipoprotein, B-type natriuretic peptide, Troponin I and coronary flow reserve, and to determine the predictors of left ventricular ejection fraction in patients with coronary microvascular disease and obstructive coronary artery disease, and in patients with coronary microvascular disease. Results: The mean age was 58.5 ± 12.5 years. In patients with obstructive coronary disease and coronary microvascular disease we found low density lipoprotein-c had significant inverse relationship with left ventricular ejection fraction, left ventricular ejection fraction also had significant negative relationship with B-type natriuretic peptide, and Troponin-I. While a significant direct relationship turned out to be observed linking left ventricular ejection fraction with coronary flow reserve. Left ventricular ejection fraction had significant negative relationship with low density lipoprotein, and B-type natriuretic peptide in patients with obstructive coronary artery disease only. Age, blood pressure, lipid levels, red cell distribution width, glycated hemoglobin, symptoms, New York heart association classification, alcohol drinking, hypertension, diabetes mellitus, troponin levels and B-type natriuretic peptide were the predictors for left ventricular ejection fraction in coronary microvascular disease patients.
Keywords: Coronary artery microvascular dysfunction (CMVD); Coronary flow reserve (CFR); Left ventricular ejection fraction (LVEF); Low density lipoprotein- cholesterol (LDL-c); B-type natriuretic peptide (BNP)
Coronary artery disease is a major non communicable disease problem around the world. The coronary vessels damage can be caused by an array of crucial risk factors such as hypertension, dyslipidemia, diabetes mellitus and smoking cigarettes [[
Previous studies were done to investigate serum total cholesterol in relation to left ventricular ejection fraction and coronary artery disease where they found out higher total cholesterol and high density lipoprotein are associated with higher left ventricular ejection fraction [[
In our study, we used a prospective clinical observational design to investigate the association between left ventricular ejection fraction and low density lipoprotein, B-type natriuretic peptide, Troponin-I, and coronary flow reserve and to determine the predictors of left ventricular ejection fraction.
We recruited 40 patients attending Union hospital for the first time divided into two sub-group where by half had coronary microvascular disease and the other half had obstructive coronary artery disease.
A prospective clinical observational study.
- ST-T dynamic variations on ECG (ST segment desolation, symmetrical T wave reversion, or dynamic change that appears at the time when the chest discomfort occurs).
- Coronary artery examination by coronary angiography was accomplished.
- 18–79 years of age.
- We recruited patients who were showing up for the initial appointment to our medical institution and not in any treatment at all.
- Acute myocardial infarction.
- Patients who had percutaneous coronary intervention and those who had coronary artery bypass graft.
- A further cardiac disorders affecting ventricular wall motion or cardiac ejection function, such as stress cardiomyopathy, hypertrophic cardiomyopathy, dilated cardiomyopathy, myocarditis, myocardial amyloidosis.
- Severe arrhythmias such as permanent atrial fibrillation, recurrent and poorly controlled ventricular arrhythmias.
- Severe valvular heart disease.
- Follow up patients on medications including statins.
- Allergic habitus.
- Patients or their family members refused to participate in the study.
- Coronary microvascular dysfunction: ST-segment depression or T-wave inversion on ECG but had TIMI 3 flow on Coronary angiography.
- Obstructive coronary artery disease: ST-segment depression or T-wave inversion on ECG and either TIMI I or II flow on CAG.
The intention of this research was evaluating the relationship between left ventricular ejection fraction and low density lipoprotein, brain natriuretic peptide, Troponin I and coronary flow reserve, and to determine the predictors of left ventricular ejection fraction in patients with coronary microvascular disease and obstructive coronary artery disease.
PET-CT scan was used to measure coronary flow reserve and assess the microvascular coronary perfusion. The images were obtained using a dedicated PET/CT scanner (Discovery VCT
A cutoff CFR value for our study was 2.6 [[
The statistical analysis was done using IBM SPSS Statistics for Windows, Version 20.0. Armonk, NY: IBM Corp, USA.
Baseline patient characteristics were summarized. All data are presented as mean ± SD for continuous variables and n (%) for categorical variables. Comparisons between groups were made using Pearson correlation or Spearman's rho for continuous variables and Fisher exact test for categorical variables. A P-value of < 0.05 was considered statistically significant. A multivariate linear regression model was done to determine the predictors of LVEF.
The clinical protocol and the informed consent forms were approved by the ethics committee of Tongji medical college of Huazhong University of science and technology. All patients read and signed the published informed consent. This clinical study was conducted according to the revised declaration of Helsinki concerning biomedical research in using patient information.
Forty patients participated in our study, whereby 20 patients had coronary microvascular dysfunction and 20 patients had obstructive coronary artery disease. The mean age was 58.5 ± 12.5 years. Approximately 60% of the patients were women. The mean left ventricular ejection fraction was 56.7 ± 7.9, and the mean coronary flow reserve was 2.04 ± 0.56 respectively. The patient's demographic and clinical characteristics are summarized in Table 1.
Demographics and clinical characteristics of patients (n = 40)
Characteristics CMVD (n = 20) OCAD (n = 20) Age (years)a 48.45 ± 12.7 58.45 ± 12.7 Females, n (%) 12 (60) 12 (60) Smokers, n (%) 8 (40) 12 (60) Alcoholic, n (%) 6 (30) 12 (60) Hypertensive, n (%) 9 (45) 17 (85) Diabetic, n (%) 3 (15) 13 (65) Chest pain, n (%) 10 (50) 8 (40) Chest tightness, n (%) 9 (45) 1 (5) Difficulty in breathing, n (%) 1 (5) 7 (35) NYHA (Class I), n (%) 16 (80) 4 (20) NYHA (Class II), n (%) 4 (20) 8 (40) NYHA (Class III), n (%) 0 (0) 6 (30) NYHA (Class IV), n (%) 0 (0) 2 (10) Systolic blood pressure (mmHg)a 131.5 ± 20.0 141.7 ± 21.0 Diastolic blood pressure (mmHg)a 81.75 ± 12.8 83.45 ± 20.0 LDL-C (µmol/l)a 3.5 ± 1.6 3.5 ± 1.7 HDL-C (µmol/l)a 1.18 ± 0.46 1.15 ± 0.35 Troponin-I (pg/ml)a 13.1 ± 9.4 24.9 ± 20.0 Red cell distribution width (%)a 14.9 ± 3.2 16.0 ± 3.3 Glycated hemoglobin A1Ca 5.7 ± 1.8 6.9 ± 1.7 Brain natriuretic peptide (pg/ml)a 50.3 ± 38.0 176.2 ± 98.9 Ejection fraction (%)a 61.5 ± 6.4 51.9 ± 6.4 Coronary flow reservea 1.67 ± 0.28 2.42 ± 0.51
NYHA New York Heart Association, LDL-C low density lipoprotein cholesterol, HDL-C high density lipoprotein cholesterol
We hypothesized that the factors influencing left ventricular ejection fraction for patients with coronary microvascular disease and obstructive coronary artery disease to be LDL-C, BNP, Troponin-I and CFR. We conducted correlation tests using Spearman's rho to assess the relationship between LVEF, LDL-C, BNP, Troponin-I and CFR in patients with CMVD and OCAD (Fig. 1a–d). Low density lipoprotein-c (LDL-c) had significant inverse relationship with LVEF (r = − 0.323, P = 0.042), LVEF also had significant negative relationship with BNP (r = − 0.562, P < 0.0001), and Troponin-I (r = − 0.311, P = 0.04). While a significant positive relationship was observed between LVEF and CFR (r = 0.422, P = 0.007).
Graph: Fig. 1 a A negative correlation between LVEF (%) and LDL-C (µmol), b a negative relationship between LVEF (%) and BNP (pg/ml), c a positive correlation between LVEF (%) and CFR, and lastly, d a negative relationship between LVEF (%) and Troponin I (pg/ml)
Left ventricular ejection fraction had significant negative relationship with LDL-C, and BNP. We observed fewer factors influencing the LVEF when we separated OCAD from CMVD patients, and there was no correlating factor in CMVD subgroup.
- In patients with coronary microvascular disease and obstructive coronary artery disease
A backward multivariate linear regression model was done for determination of predictors of LVEF in patients with CMVD and OCAD. In this study, the variables Age, symptoms, NYHA classification and BNP qualified to enter the model. After adjusting for confounders, the patients age (coefficient β = 0.19, 95% CI 39.5–58.6, P = 0.023), Difficulty in breathing (coefficient β = − 6.95, 95% CI (− 11.9) to (− 2.0), P = 0.007), NYHA Class III (coefficient β = − 7.14, 95% CI (− 12.55) to (− 1.74), P = 0.011), NYHA Class IV (coefficient β = − 17.25, 95% CI (− 26.18) to (− 8.32), P < 0.0001), and BNP (coefficient β = − 0.03, 95% CI (− 0.042) to (− 0.019), P < 0.0001) were determined as predictors of LVEF in patients with CMVD and OCAD.
- In patients with coronary microvascular disease.
After adjusting for confounders, the patients age (coefficient β = 1.31, 95% CI 1.07–1.55, P < 0.0001), systolic blood pressure (coefficient β = − 0.58, 95% CI (− 0.76) to (− 0.41), P < 0.0001), diastolic blood pressure (coefficient β = − 1.71, 95% CI (− 2.14) to (− 1.28), P < 0.0001), HDL (coefficient β = − 4.8, 95% CI (− 8.5) to (1.14), P = 0.02), HbA1c (coefficient β = 2.69, 95% CI 1.66–3.74, P = 0.001), Chest tightness (coefficient β = 33.3, 95% CI 26.4–40.2, P < 0.0001), difficulty in breathing (coefficient β = 12.3, 95% CI 6.93–17.7, P = 0.002), NYHA class I (coefficient β = 20.4, 95% CI 13.3–27.5, P = 0.001), alcohol (coefficient β = 20, 95% CI 15.6–24.6, P < 0.0001), hypertension (coefficient β = 57, 95% CI 47–67, P < 0.0001), Diabetes mellitus (coefficient β = − 64, 95% CI (− 77) to (− 51), P < 0.0001), Troponin I (coefficient β = − 1.65, 95% CI (− 1.9) to (− 1.3), P < 0.0001), and BNP (coefficient β = 0.35, 95% CI 0.24–0.46, P = 0.001) were determined as predictors of LVEF in patients with CMVD (Table 2).
Multivariate linear regression model investigating the predictors of LVEF in patients with CMVD (n = 20)
Predictors Multivariate final model Coefficient β ± SE P-value 95% confidence interval Constant 109.99 ± 5.47 < 0.0001 95–124 Age 1.31 ± 0.09 < 0.0001 1.07–1.55 Systolic BP (mmHg) (− 0.58) ± 0.07 < 0.0001 (− 0.76) to (− 0.41) Diastolic BP (mmHg) (− 1.71) ± 0.17 < 0.0001 (− 2.14) to (− 1.28) HDL (µmol/l) (− 4.8) ± 1.4 0.02 (− 8.5) to (− 1.14) RDW 2.15 ± 0.21 < 0.0001 1.6 ± 2.7 HbA1c 2.69 ± 0.4 0.001 1.66–3.74 Chest tightness 33.3 ± 2.69 < 0.0001 26.4–40.2 Difficulty in breathing 12.3 ± 2.09 0.002 6.93–17.7 NYHA class I 20.4 ± 2.7 0.001 13.3–27.5 Alcohol 20 ± 1.75 < 0.0001 15.6–24.6 Hypertension 57 ± 3.9 < 0.0001 47–67 Diabetes mellitus (− 64) ± 5 < 0.0001 (− 77) to (− 51) Troponin I (− 1.65) ± 0.13 < 0.0001 (− 1.9) to (− 1.3) BNP (pg/ml) 0.35 ± 0.043 0.001 0.24–0.46
LVEF left ventricular ejection fraction, CMVD coronary microvascular dysfunction, HDL high density lipoprotein, RDW red cell distribution width, HbA1c glycated hemoglobin, BNP brain natriuretic peptide
The current research indicated a negative correlation between LVEF and LDL-c, BNP and Troponin-I in patients with OCAD and CMVD. To the best our knowledge, this is the first research to reveal the relationship between LVEF and biomarkers.
Previous studies have shown that hyperlipidemia adversely influenced the left ventricular ejection fraction, particularly in patients with myocardial infarction. They went further and detailed an important positive correlation between left ventricular ejection fraction and high density lipoprotein-cholesterol, suggesting that HDL-cholesterol might influence left ventricular systolic function through extra-atherosclerotic mechanisms because they observed left ventricular ejection fraction was adversely influenced by dyslipidemia irrespective of the severity of coronary atherosclerosis [[
Several studies have revealed a negative correlation between BNP and LVEF. They revealed that BNP levels were low in patients with heart failure with preserved ejection fraction compared to patients with heart failure with reduced ejection fraction. In another study, they also discovered an important correlation between NT-proBNP and LVEF in elderly patients, whereby worsening LVEF had a significant correlation with NT-proBNP levels [[
Furthermore, another biomarker Troponin-I is a power indicator of myocardial necrosis, it has been studied before and was found to be inversely correlated with left ventricular ejection fraction especially in patients after first myocardial infarction. They found out that the left ventricular ejection fraction of < 50% was predicted by troponin I concentration of > 6.6 ng/ml. In another research analysis, it showed that patients with severe left ventricular systolic dysfunction (LVEF < 35%) had the highest level of troponin I and vice versa. They also showed that the LVEF had a negative correlation with troponin I levels (r = − 0.54, P = 0.001). Despite the above fact, there was an exploration of troponin T, whereby it was also revealed that there was a negative correlation between troponin T levels and LVEF (r = − 0.72, P ≤ 0.0001) [[
Moreover, there were studies done in the area of determination of predictors of LVEF. Whereby, their analysis demonstrated that several traditional and easily available factors were associated with a greater risk of heart failure development, even among low-risk CAD population. Some of the studies showed lipids predicted the severity of new onset CAD in type-2 DM patients and not in relation to LVEF, differentiating from our study. In another research, low HDL-c was strongly predictive of cardiovascular events in patients with coronary artery disease [[
We believe by sharing these findings of our study, will empower the clinicians with knowledge on coronary microvascular dysfunction in relation to OCAD, by exploring the relationship between LVEF and biomarkers, and predictors of LVEF in these patients.
There was a strong negative relationship between left ventricular ejection and biomarkers, with a significant positive association between LVEF and CFR.
A small sample size was our study limitation.
This study did not receive any funding.
We thank the Staffs and management of Union Hospital of Huazhong University of Science and Technology for granting permission to conduct this study. And we thank all patients who participated in the study.
Drafting of manuscript was done by: HAM, MM, AM, MM, PP, DM, MJ, WZ. Critical revision and correction were done by: WZ. All authors read and approved the final manuscript.
Data and materials are available upon request to the authors.
The clinical protocol and the informed consent forms were approved by the ethics committee of Tongji medical college of Huazhong University of science and technology. All patients read and signed the published informed consent. This clinical study was conducted according to the revised declaration of Helsinki concerning biomedical research in using patient information. All authors agreed for this manuscript to be published.
Not applicable.
The authors declare that they have no competing interests.
• LVEF
- Left ventricular ejection fraction
• LDL-C
- Low density lipoprotein-cholesterol
• BNP
- B-type natriuretic peptide
• CFR
- Coronary flow reserve
• CMVD
- Coronary microvascular disease
• OCAD
- Obstructive coronary artery disease
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By Henry Anselmo Mayala; Magesa Mafuru; Abdalah Mkangala; Mark Mayala; Pedro Pallangyo; Dickson Minja; Mohamed Janabi and Wang Zhao-hui
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