The Value of Using Pulsed Tissue Doppler Mitral Annulus Velocity during Dobutamine Stress Echocardiography for Assessment of Myocardial Viability in Patients with Coronary Artery Disease before Revasularization

Abstract

Background: Assessment of viability could be of significance in ischemic and heart failure patients before deciding for revascularization. The use of Dobutamine stress echocardiography has the disadvantage of subjective visual evaluation of regional wall motion, so, new technologies have been modified; one of these is to assess mitral annular velocity using tissue Doppler imaging. Aim: The aim of this study was to evaluate the value of Pulsed wave tissue Doppler mitral annulus velocity with dobutamine echocardiography in assessment of myocardial viability and prediction of functional recovery of wall motion abnormalities after revasularization in patients with coronary artery disease. Patients and methods: The study group included 40 patients, selected consecutively from patients presented to Ain Shams university Hospitals with coronary artery disease as proved by diagnostic coronary angiography and recommended for potential coronary revascularization. Each patient underwent baseline transthoracic echocardiography, in addition to low dose dobutamine echocardiography using TDI at mitral annulus in 6 different walls. All patients were subjected to revascularization (30 by PCI and 10 by CABG) then followed up after 6 months by transthoracic echocardiography to assess improvement in EF and SWMA. Results: Using the 16 segment method, a total of 640 segments were studied: 250 Segments were considered nondysfunctional (39%), 390 Segments were dysfunctional: of which, severely hypokinetc (216, 55.4 % of abnormal), 158 segments akinetic (40.5% of abnormal), and 16 Segments were dyskinetic (4.1% of abnormal). The mean SWM index at rest was 1.9 (0.39).Using low dose dobutamine echocardiography, 220 segments were detected to be viable (56.4%), while 170 were non-viable (43.6%). In order to relate the results of TDI, The 16 segments were reevaluated into 6 walls per patient. Using this method, 240 walls were studied. 19 walls were excluded due to technical difficulties in assessment of TDI. Pulsed wave TDI demonstrated that dysfunctional areas had lower systolic velocities compared to areas considered as normal. Similarly, the increase from baseline to DSE (ΔTDI) was higher in nondysfunctional areas vs. dysfunctional areas. However, there was no significant difference in the mean TDI at rest for viable and non-viable walls as detected by dobutamine stress echocardiography. But the increase in TDI velocity with peak dobutamine was significantly more in viable (1.97±0.44) vs. nonviable (1.14±0.54) walls, with p<0.0001.The ejection fraction improved from 39.87±8.22 (mean + STD) at baseline to 46.13±8.58 (mean + STD) at follow-up. The score index of the segmental wall motion during follow up after revascularization was 1.45±0.29 (mean+STD). Among the total dysfunctional segments detected at baseline echocardiography, follow-up echo postoperatively showed improvement by ≥1 score in 239 segments (61.3 %).In the 220 dobutamine positive segments, 182 segments improved postrevacsularization (82.7%) while 38 did not show improvement (17.3%), whereas in the segments designated as dobutamine non-viable, 122 segments were not improved (71.8%) and 48 segments (28.2%) improved post revascularization. Taking improvement as the gold standard for viability, sensitivity of dobutamine is: 82.7%, specificity 71.8%, PPV 79.1%, NPV 76.3%. Using TDI method, 115 (79.3%) walls were diagnosed as viable by this method, while 30 walls were nonviable (20.7%). 80 walls (55.2% of total studied walls) were detected to be viable by both dobutamine conventional 2D echocardiography and dobutamine TDI echocardiography (systolic wave), On the other hand, 27 walls (18.6% of total studied walls) were detected to be non-viable by both methods. However, 38 walls (26.2% of total abnormal walls) showed discordance between the two methods. The improvement of 74 walls of 80 combined TDI& DSE positive walls, making a sensitivity of 90.2%, similarly 24 of 27 concordant TDI & DSE negative walls did not improve, making a specificity of 92.3%. Conclusion: The current study confirmed the importance of using TDI in different mitral annular sites, as an objective tool in detecting myocardial viability, and to improve the sensitivity and specificity of DSE.