Patients Demographic and clinical characteristics
Forty patients participated in our study, whereby twenty patients had coronary microvascular dysfunction (CMVD) and twenty patients had obstructive coronary artery disease (OCAD). 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.
Table 1
Demographics and Clinical Characteristics of Patients (n = 40)
| |
Variables | Value |
Age (mean ± SD) | 58.5 ± 12.5 |
Gender n (%) | |
• Male | 16 (40) |
• Female | 24 (60) |
Symptoms n (%) | |
• Chest pain | 18 (45) |
• Chest tightness | 10 (25) |
• Difficulty in breathing | 8 (20) |
• mixed symptoms | 4 (10) |
NYHA classification n (%) | |
• Class I | 20 (50) |
• Class II | 12 (30) |
• Class III | 6 (15) |
• Class IV | 2 (5) |
Smoking, n (%) | 20 (50) |
Alcohol, n (%) | 18 (45) |
Hypertension, n (%) | 26 (65) |
Diabetes mellitus, n (%) | 16 (40) |
Systolic BP in mmHg, (mean ± SD) | 136.6 ± 20.9 |
Diastolic BP in mmHg, (mean ± SD) | 82.6 ± 16.6 |
LDL-C in µmol/l, (mean ± SD) | 3.5 ± 1.6 |
HDL-C in µmol/l, (mean ± SD) | 1.16 ± 0.4 |
Troponin I in pg/ml, (mean ± SD) | 18.9 ± 16.5 |
Red cell distribution width, n (%) | 15.5 ± 3.2 |
Glycated Hemoglobin | 6.3 ± 1.8 |
BNP in pg/ml, (mean ± SD) | 113.3 ± 167.8 |
Left ventricular ejection fraction | 56.7 ± 7.9 |
Coronary flow reserve | 2.04 ± 0.56 |
LDL-C, low density lipoprotein- cholesterol, HDL-C, high density lipoprotein-cholesterol, BNP, brain natriuretic peptide, SD, standard deviation |
Relationship between left ventricular ejection fraction (LVEF), LDL-c, BNP, troponin-I and CFR in patients with CMVD and OCAD
We hypothesized that the factors influencing left ventricular ejection fraction for patients with CMVD and OCAD 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, B, C and 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 < .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).
Relationship between left ventricular ejection fraction (LVEF), LDL-C and BNP in patients with OCAD
Left ventricular ejection fraction had significant negative relationship with LDL-C, and BNP. We observed fewer factors influencing the left ventricular ejection fraction when we separated OCAD from CMVD patients, and there was no correlating factor in CMVD subgroup.
Determination of predictors of LVEF
i) In patients with CMVD and OCAD
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) -(-2.0), P = 0.007), NYHA Class III (coefficient β= -7.14, 95% CI, (-12.55) -(-1.74), P = 0.011), NYHA Class IV (coefficient β= -17.25, 95% CI, (-26.18) -(-8.32), P < .0001), and BNP (coefficient β= -0.03, 95% CI, (-0.042) -(-0.019), P < .0001) were determined as predictors of LVEF in patients with CMVD and OCAD.
After adjusting for confounders, the patients age (coefficient β = 1.31, 95% CI, 1.07–1.55, P < .0001), systolic blood pressure (coefficient β= -0.58, 95% CI, (-0.76)-(-0.41), P < .0001), diastolic blood pressure (coefficient β= -1.71, 95% CI, (-2.14)-(-1.28), P < .0001), HDL (coefficient β= -4.8, 95% CI, (-8.5)- (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 < .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 < .0001), Hypertension (coefficient β = 57, 95% CI, 47–67, P < .0001), Diabetes mellitus (coefficient β= -64, 95% CI, (-77)- (-51), P < .0001), Troponin I (coefficient β= -1.65, 95% CI, (-1.9)-(-1.3), P < .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).
Table 2
Multivariate linear regression model investigating the predictors of LVEF in patients with CMVD (n = 20)
| | | |
| Multivariate Final Model |
Predictors | Coefficient β ± SE | P-value | 95% Confidence Interval |
Constant | 109.99 ± 5.47 | < .0001 | 95–124 |
Age | 1.31 ± 0.09 | < .0001 | 1.07–1.55 |
Systolic BP (mmHg) | (-0.58) ± 0.07 | < .0001 | (-0.76) -(-0.41) |
Diastolic BP (mmHg) | (-1.71) ± 0.17 | < .0001 | (-2.14) -(-1.28) |
HDL (µmol/l) | (-4.8) ± 1.4 | 0.02 | (-8.5) -(-1.14) |
RDW | 2.15 ± 0.21 | < .0001 | 1.6 ± 2.7 |
HbA1c | 2.69 ± 0.4 | 0.001 | 1.66–3.74 |
Chest tightness | 33.3 ± 2.69 | < .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 | < .0001 | 15.6–24.6 |
Hypertension | 57 ± 3.9 | < .0001 | 47–67 |
Diabetes mellitus | (-64) ± 5 | < .0001 | (-77) -(-51) |
Troponin I | (-1.65) ± 0.13 | < .0001 | (-1.9) -(-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 |