DIAGNOSIS OF LV THROMBUS: A DEFINITE ROLE FOR CONTRAST ECHOCARDIOGRAPHY?

Abstract

Patients with documented LV thrombus following acute anterior myocardial infarction are at a higher risk of thromboembolic complications. Clear distinctions between the echocardiographic interpretations of “suspected LV thrombus”, “unable to rule out thrombus”, and “no thrombus”, are important as they carry differing strengths of recommendation for anticoagulation use in current ACS treatment guidelines. Both the 2007 CCS and 2008 ASE consensus statements advocate for use of contrast echocardiography to confirm or exclude apical thrombus. We sought to define current use of contrast echocardiography in this context and its impact on clinical decision making. This was a sub-study of a prospective, observational study of 50 consecutive patients admitted to the CCU at Vancouver General Hospital between December 2012 to January 2014 who had an acute anterior MI complicated either by documented LV thrombus or LV dysfunction (LVEF ≤40%) along with apical or anterior wall akinesis. Transthoracic echocardiography (TTE) was used for quantification of LV function and detection of LV thrombus. Contrast echocardiography, using Definity (Perflutren Lipid Microsphere, Lantheus Medical Imaging) was available in all cases. The decision to use contrast TTE was left to the attending cardiologist. Anticoagulation use was determined by the discharge prescription on record. In this group, 24/49 (49%) had TTE evidence of LV thrombus or were unable to rule out thrombus. TTE documented LV thrombus in 7 (14%) patients. In one of these cases, contrast TTE was used, and was negative, disproving LV thrombus and leading to discontinuation of anticoagulation. In 17 (35%) patients, initial TTE was unable to rule out LV thrombus. Contrast TTE was used in 10/17 (58.8%) indeterminate cases. Of these contrast TTE scans, 9/10 ruled out LV thrombus leading to discontinuation of anticoagulation. One contrast TTE was positive for LV thrombus and led to prescription of anticoagulation. Of the remaining 7/17 (41%) indeterminate TTE, 4 patients were anticoagulated empirically and 3 patients were kept on dual antiplatelet only. LV thrombus is difficult to confidently image using standard TTE. As recommended by national guidelines, contrast echocardiography can be useful to aid in the diagnosis of apical thrombus. In our study, management decisions regarding anticoagulation were concordant with contrast echo results in all 11 cases. Further study into the routine use of contrast echocardiography as part of a clinical decision making algorithm for high risk MI patients with an indeterminate standard TTE is needed.