ASSESSMENT OF MYOCARDIAL VIABILITY USING LOW DOSE DOBUTAMINE THREE DIMENSIONAL SPECKLE TRACKING STRESS TRANSTHORACIC ECHOCARDIOGRAPHY

Abstract

Background: Three-dimensional speckle tracking echocardiography (3D STE) is used recently to assess many cardiac diseases; it is considered as natural growth of two-dimensional speckle tracking echocardiography (2D STE). The LV mechanics is in nature a 3D phenomenon and its accurate assessment requires a 3D imaging method. 3DSTE has been implemented for measuring 3D strain, and has emerged as a more physiologically sound tool for analyzing the complexity of LV mechanics, overcoming the inherent limitations of 2D STE. Objective: To determine the relative accuracy of area strain measured by 3D speckle-tracking echocardiography combined with low dose dobutamine for the detection of myocardial viability before coronary revascularization in comparison with MPI. Patients and Methods: The study included 40 patients referred to Bab El-She’riya University Hospital nuclear lab for assessment of myocardial viability by MPI before coronary revascularization. Then all patients were referred to Islamic Cardiac Center Echo lab where complete conventional transthoracic echocardiography was done followed by Low dose dobutamine (LDD) stress transthoracic echocardiography with 3D STE then comparing results of 3D strain of viable segments with that of nonviable segments and with corresponding segments in MPI studies. Results: The study showed that 241 segments in the 40 patients were assigned as abnormal segments, 114 were viable and 127 were nonviable, resting area strain (AS)was -18.7±2.5 for viable segments comparing to -12.6±5.3 for non-viable segment. A cut-off point of -16 was chosen to differentiate viable segments from non-viable ones with sensitivity 80.75% and specificity 83.1%. The average LDD AS value for viable segments was-24.5±2.7 and was -15.2±4.8 of non-viable segments with a cut-off point of -24 to differentiate viable segments from non-viable ones with sensitivity of 84.75% and a specificity of 89.1%. The average increase of AS of viable segments after LDD was -5.8±2.3 with a cut-off point to detect viability was a -0.24 increase in LDD from resting AS with a sensitivity of 95.75% and a specificity of 98.1%. Conclusion: AS obtained from 3D STE may be used clinically as an indicator to detect myocardial viability with higher sensitivity and specificity when combined with LDD.