Complementary Value of Tissue Doppler Imaging in Dobutamine Stress Echocardiography: A Prospective Cohort Study

Abstract

Introduction: In patients with Coronary Artery Diseases (CAD), the presence of viable myocardium predicts the recovery of Left Ventricular (LV) systolic function after revascularisation. The identification of myocardial viability during dobutamine stress echocardiography is subjective and with observer bias. Tissue Doppler Imaging (TDI) echocardiography has opened new possibilities for non-invasive quantification of myocardial function by directly interrogating myocardial velocity with high temporal and spatial resolution. Aim: To determine the baseline regional myocardial and mitral annular Maximum Systolic Velocities (MSV) in patients with LV dysfunction and to compare the MSV values in viable and nonviable myocardium. Materials and Methods: In this prospective Cohort study, TDI of regional and annular LV myocardial velocities was performed at the baseline (at rest) in 352 patients with CAD and LV dysfunction who were referred for Dobutamine stress Echocardiography. Viability assessment by 2 Dimensional (2D) methods was done simultaneously using routine Dobutamine stress protocol. Patients were grouped in two groups based on the presence or absence of viability with 2D stress echocardiography. TDI velocities were compared in the two groups of patients with and without myocardial viability. Measurements of regional wall thickness, Ejection Fraction(EF) and Wall Motion Score Index (WMSI) were done to assess the regional and global LV function in these patients. Those patients who underwent revascularisation were subsequently assessed for functional recovery by 2D and TDI echocardiography before discharge from the hospital. Analyses were conducted using Statistical Package for Social Sciences(SPSS) version 16.0. Results: Among 352 patients studied (124 females and 228 males), mean age 58 years (range 36 to 75 years). A total of 243 patients (69%) with viable myocardium as per 2D echocardiography had higher cut-off Baseline Regional Maximum Systolic Velocity (BRMSV) >0.03 m/s and baseline mitral annular systolic velocity >0.06 m/s with high sensitivity and specificity compared to patients with severe contractile dysfunction and non-viable myocardium. Conclusion: Tissue doppler parameters like regional myocardial systolic and mitral annular velocities have shown significantly higher cut-off values in those patients with ischaemic and viable myocardium compared to non-viable myocardium.