Study population and protocol
We enrolled 166 patients of DCMP or ICMP who were come to our center for diagnostic evaluation between January 2021 and May 2023. Patients were selected based on inclusion criteria with signs and symptoms of heart failure, accompanied by echocardiographic evidence of LV dilatation associated with reduced left ventricular systolic function (LVEF ≤ 40%). The study’s primary aim was to compare echocardiographic and biochemical parameters of heart failure by evaluating serum biomarker- NT pro-BNP, echocardiographic parameter of LVEF, GLS, E/e’ with LAAWV. We enrolled patients based on the inclusion criteria of (1) Patients aged >18 years, (2) New York Heart Association functional class II to III with left ventricular ejection fraction ≤40%.
154 patients had echocardiographic images of sufficient quality for further two-dimensional myocardial deformation analysis and LAAW velocity. We could not measure TTE-LAWV in 6 patients, because of obesity, chronic obstructive pulmonary disease, or emaciation, and another 6 patients didn’t meet the criteria for obesity with a BMI of <30, and these patients were excluded from the study. These patients comprise the cohort of the present echocardiographic sub-study.
Study Patients with- (1) Primary valvular heart disease, (2) Acute myocarditis (onset in the previous three months), (3) Acute myocardial infarction as suspected by clinical presentation or diagnostic tests, (4) Obese patient with BMI >30, (5) Patients with other co-morbidities that may limit life expectancy to less than one year, were excluded from the study.
Study patients underwent a clinical evaluation and routine laboratory tests, including complete blood count, creatinine, and B-type natriuretic peptide (BNP). All the patients underwent transthoracic echocardiography and were treated according to the guideline and provided informed consent.
We performed the echocardiographic evaluation using GE Vivid E9 ultrasound machines equipped with a 2.5-MHz probe. All images were digitally stored and later analyzed offline. We measured the LV end-systolic and end-diastolic volumes and calculated the LV ejection fraction (LVEF) using the Simpson biplane method. Mitral E and A peak velocities were measured to determine the ratio of early-diastolic LV inflow velocity to atrial-systolic velocity (E/A). Furthermore, we obtained the average tissue Doppler-derived early diastolic mitral annular velocity (e’) from measurements taken at both the septal and lateral sides of the mitral annulus. We calculated the average ratio of early-diastolic LV inflow velocity to early-diastolic mitral annular velocity (E/e’).
Using two-dimensional speckle tracking echocardiography, myocardial deformation analysis (LV GLS) was performed in this study. Echocardiographic images were acquired at a frame rate of 50-70 frames per second (with individual adjustments made for optimal analysis). A digital loop was acquired from three apical views, including four-, two-, and three-chamber views. For LV GLS analysis, after manually selecting the cardiac cycle, the LV endocardial border was manually traced at the end-systolic frame. The GLS was calculated by averaging the mean values of all valid segments obtained from the speckle tracking analysis.
LAAWV was assessed using transthoracic tissue Doppler echocardiography (TDE). To obtain the LAAWV, we first identified the triangle-shaped left atrial appendage (LAA) on the left side of the aortic root in the parasternal short-axis view. Then, a sample volume was placed very close to the tip of the LAA, and the LAAWV was measured using pulsed transthoracic TDE. LAWV, specifically defined as LAA peak wall velocity, was measured using Doppler tissue imaging (DTI) with the sample volume of pulsed-wave Doppler positioned on the LAA tip, as previously reported. LAAWV was calculated by averaging the maximum negative peak wave velocity within each RR interval over 10 cardiac cycles, excluding the signals from the mitral ring motion. To ensure accuracy, the Doppler beam angle was corrected by observing the direction of the longitudinally contracting LAA. Additionally, the left atrial (LA) dimension was conventionally measured using M-mode transthoracic echocardiography.