| Objective:Myocardial ischemia is one of the most important causes of left ventricular (LV) diastolic dysfunction. Many patients with coronary artery disease (CAD) have normal LV systolic function in the early phase, and the abnormalities of LV filling may occur prior to systolic dysfunction. It has been shown that N-terminal pro-B-type natriuretic peptide (NT-proBNP) level is involved with LV diastolic function and coronary stenosis. The role of real-time three-dimensional echocardiography (RT-3DE) in the assessment of LV diastolic function is still worthy of further study. In combination with traditional two-dimensional indices and NT-proBNP level, we sough to explore the value of RT-3DE derived parameters in the assessment of LV diastolic function in stable CAD patients.Methods:Sixty-five stable CAD patients with normal LV ejection fraction were enrolled. They were divided into3groups according to the degree of coronary stenosis:group A (n=15) with<50%stenosis as the normal control group, group B (n=25) with mild stenosis (50%-70%), and group C (n=25) with>70%stenosis. Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were examined, and its predictive ability for coronary stenosis>70%was evaluated by the receiver operating characteristic curve (ROC curve). The ratio of transmitral to annular velocities during early filling (E/E’), measured by two-dimensional echocardiography (2DE), was used as an index of LV filling pressure. LV volume-time curves (VTCs) were acquired using RT-3DE, and then peak filling rate (PFR), mean filling rate (MFR) and1/3filling fraction (1/3FF) were measured to evaluate the LV diastolic function. The correlations of RT3DE-derived LV diastolic parameters with E/E’and plasma NT-proBNP levels were analyzed, respectively. The ROC curve of RT3DE-derived parameter was analyzed to identify the predictive value for coronary stenosis.Results:The plasma NT-proBNP levels of group B and C were significantly higher than those of the normal control group (P<0.01). There were no significant differences in all other demographic and clinical parameters between each two groups. When conventional2DE parameters were compared, The group B and C showed significantly lower mitral E, the ratio of mitral peak velocities during rapid filling and atrial contraction (E/A), E’and higher E/E’than those in the normal control group (P<0.05), groups were similar with respect to the other2DE indices. The NT-proBNP level was positively correlated with E/E’ratio (r=0.607, P<0.01), and the area under the ROC curve (AUC) of NT-proBNP level was0.727(P=0.002), with95%confidence interval at0.601～0.853. The sensitivity and specificity of NT-proBNP level≥610.70pmol/L for diagnosing coronary stenosis>70%were68%and75%, respectively. With the worsen of coronary stenosis, PFR and1/3FF decreased gradually. PFR and1/3FF in group B and C were significantly lower than those in the normal control group (P<0.05), and while MFR showed no differences between each two groups. PFR and1/3FF both inversely correlated with E/E’and NT-proBNP level, respectively, with1/3FF presenting higher correlation coefficients (for E/E’, r=-0.751, P<0.01; for NT-proBNP level, r=-0.612, P<0.01). By the ROC curve, AUC of1/3FF was0.772(P=0.001), with95%confidence interval at0.633～0.911. The sensitivity and specificity of1/3FF≥36.75%for coronary stenosis<70%were73%and76%, respectively.Conclusions:It is suggested that the VTC by RT-3DE can be used to assess LV diastolic function in stable CAD patients with different degrees of coronary stenosis qualitatively and quantitatively. To a certain degree,1/3FF could detect mild diastolic dysfunction characterized by myocardial relaxation abnormalities in these patients at the early times. Plasma NT-proBNP level and1/3FF appear to be possible predictors for diagnosing severe coronary stenosis. Objective:As a robust marker of left ventricular (LV) diastolic dysfunction, left atrial (LA) enlargement assessment by new techniques, such as real-time three-dimensional echocardiography (RT-3DE), has become one of the most interesting research hotspots in the cardiovascular field. Most studies had focused on the value of left atrial maximum volume (LAVmax). However, other LA volumes have not been well studied. We aimed to assess LV diastolic function by measuring LA phasic volumes and function using RT-3DE in patients with stable coronary artery disease (CAD).Methods:Sixty-five stable CAD patients with normal LV ejection fraction (EF) were enrolled. They were divided into3groups according to the degree of coronary stenosis: group A (n=15) with<50%stenosis as the normal control group, group B (n=25) with mild stenosis (50%～70%), and group C (n=25) with≥70%stenosis. Plasma N-terminal pro-B-type natriuretic peptide (NT-proBNP) levels were examined. LA phasic volumes and function were evaluated and compared using both RT-3DE and two-dimensional echocardiography (2DE). LAVmax, LA minimum volume (LAVmin), and LA volume onset of P wave on electrocardiography (LAVpre-p) were measured and indexed to body surface area, respectively. LA total EF (LAEF), LA passive EF (LAEFpassive), and LA active EF (LAEFactive) were calculated. The correlations of RT-3DE-derived parameters with other conventional indices, including the ratio of transmitral to annular velocities during early-filling (E/E’) and plasma NT-proBNP levels, were analyzed. The predictive ability of RT-3DE-derived parameters for coronary stenosis≥70%was evaluated by calculating the area under the receiver operating characteristic curves (ROC curves).Results:Compared with the normal control group, patients in group B and C showed significantly higher NT-proBNP levels and E/E’, lower mitral E, the ratio of mitral peak velocities during rapid filling and atrial contraction (E/A) and E’(P<0.05). No significant differences were found in all other demographic and2DE parameters between each two groups. There were good correlations between RT-3DE and2DE for the LAV measurements (group A, r=0.933, P<0.01; group B, r=0.936, P<0.01; group C, r=0.896, P<0.01). For the comparisons of LA phasic volumes and function within each group, the values acquired by the two techniques were similar in group A and B. In group C, however, the LAVmin index was significantly lower by RT3DE compared with that by2DE (P<0.05), while the LAVmax (P>0.05) and the LAVpre.P (P=0.054) indices failed to reach significant differences. For the comparisons of RT-3DE-derived LA volume indices, patients with severe coronary stenosis presented higher LAVmin and LAVpre-P indices and lower LAEF and LAEFpassive.Significant correlations of RT-3DE-derived LA volume indices with E/E’ratio and plasma NT-proBNP level were found, with LAVmin index presenting highest correlation coefficients (for E/E’, r=0.695, P<0.01; for NT-proBNP level, r=0.630, P<0.01). The predictive ability of RT-3DE-derived LAVmin index for coronary stenosis>70%was better than those of LAVmax and LAVpre.p indices. The area under the ROC curve of LAVmin index was0.716(P=0.004),95%confidence interval was0.591-0.841. The sensitivity and specificity of LAVmin index>13.82ml/m2for diagnosing coronary stenosis>70%were72%and70%, respectively.Conclusions:LA phasic volumes and function are measured accurately by RT-3DE in stable CAD patients. The RT-3DE-derived LA volume indices may be superior to2DE measurements for the evaluation of the severity of coronary lesions and LV diastolic function. Compared with LAVmax, RT-3DE-derived LAVmin index correlates better with E/E’ratio and NT-proBNP level and appears to be a more sensitive marker for LV diastolic function in stable CAD patients with preserved LV systolic performance. |
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