Myocardial function following Inerventional Reperfusion in Acute Myocardial Infrction : Tissue Doppler Imaging Versus Two Dimentional Echocardiographic Assessment

Abstract

Restoring patency of the infarct-related artery (IRA) with consequent reperfusion aims at the ultimate goal of limiting infarction size and minimizing the extent of damage. There has been controversy concerning the efficacy of different methods of repefusion with primary PC! & . facilitated PC!(1/2 dose of SK, + Gp lib/Ilia antagonist 'tirofiban' and stenting) claimed superior to pharmacologic thrombolysis with SK alone. The introduction of tissue Doppler imaging (TDI) technique has provided the physicians with a simple non invasive way of assessing myocardial regional wall motion abnormalities (R WMA) thus permitting a semiquantitative way of evaluating the effects of reperfusion in acute MI. The present work is intended to compare the effects of 3 different ways of reperfusion: Thrombolytic therapy using SK with (primary PC!and facilitated PC!and stenting) in pts with AMI using the technique of TDI to evaluate the extent of RWMA before and after intervention. We studied 25 pt with AMI (21 M, 4F age 41:±:8) admitted to Critical Care Medicine of Cairo University (19 Anterior MI, 6 inf. MI). Six pts received Sk. (1.5 million infusion), II were subjected to lry stenting to IRA and 8 had facilitated PC!(Sk, tirofiban) followed by stenting to IRA. Following clinical evaluation and routine laboratory testing all pts were subjected to 2D & M-mode echocardiography. Echo parameter assessed comprised RWMA using a modified 12 segment scoring system in 2 different views, TDI was done according to recommendations of American Society of echocardiography to display tissue velocities. The high pass filter was bypassed and lower gain amplification was used. Each left ventricular wall was divided into three segments of equal length to obtain basal, mid and apical segments. The latter was not analyzed because of suboptimal image quality. TDI was expressed in tenns of peak systolic wave (S) representing systolic function, with early diastolic wave (E), late diastolic wave (A) and E/A ratio representing diastolic function. Compared to control group, those with acute anterior MI exhibited significantly basal wall lower peakS wave of the (6.1 ±I vs 10.3 ± 4, P: < 0.05), lower E waves (8.0 vs 13.4, P: <0.05) and lower E/A ratio (1.23 vs 2.4, P: <0.05) with little insignificant change in the peak A (6.75 vs 6.2, P: >0.05). Compared to control groups, those with acute inferior MI exhibited signilicantly basal wall lower peak S wave (5.6 ± 3 vs 9.6 ± I, P: < 0.05), lower E waves (6.3 ± 3 vs 17 ± 3, P: <0.05) and lower E/A ratio (0.8 vs 2.2, P: <0.05) with little insignificant change in the peak A (7.1 ± 4 vs 8± 2, P: >0.05). Compared to pts who received SK, those subjected to primary PC! exhibited significantly greater immediate % improvement in the anterior basal wall in terms of higher peak S (25.8% vs 4.4%) with little changes in E and A waves. Also pts subjected to facilitated PC! demonstrated significantly higher% improvement in anterior basal wall in terms of higher peakS (18.4% vs 4.4%), with little changes in E and A waves. Conclusion: I. Being a non invasive technique TDI in our study provides a clear way of assessing adequate perfusion and RWMA in ischemic patients with acute MI compared to normal controls. 2. Applied promptly to pts with acute MI, TDI provides definite superiority of interventional over pharmacological treatment in restoring RWMA.