EMBOLIC POTENTIAL, PREVENTION AND MANAGEMENT OF MURAL THROMBUS COMPLICATING ANTERIOR MYOCARDIAL-INFARCTION - A METAANALYSIS

Objectives. The management of mural thrombus complicating acute anteri or myocardial infarction remains controversial in part because of the small size of studies on this topic. We performed a meta-analysis of p ublished studies to address three questions: 1) What is the embolic ri sk of mural thrombi after myocardial infarction? 2) What is the impact of systemic anticoagulation in reducing the embolic risk of mural thr ombi? 3) What is the impact of systemic anticoagulation, thrombolytic therapy and antiplatelet therapy in preventing mural thrombus formatio n? Methods. Studies were identified by a computerized and manual searc h and were included if they were published in manuscript form in the E nglish-language literature. Pooling of data was performed by calculati ng the Mantel-Haenszel odds ratio and an event rate difference by the method of DerSimonian and Laird. Results. The odds ratio for increased risk of emboli in the presence of echocardiographically demonstrated mural thrombus (11 studies, 856 patients) was 5.45 (95% confidence int erval [CI] 3.02 to 9.83), and the event rate difference was 0.09 (95% CI 0.03 to 0.14). The odds ratio of anticoagulation versus no anticoag ulation in preventing embolization (seven studies, 270 patients) was 0 .14 (95% CI 0.04 to 0.52) with an event rate difference of -0.33 (95% CI -0.50 to -0.16). The odds ratio of anticoagulation versus control i n preventing mural thrombus formation (four studies, 307 patients) was 0.32 (95% CI 0.20 to 0.52), and the event rate difference was -0.19 ( 95% CI -0.09 to -0.28). The odds ratio for thrombolytic therapy in pre venting mural thrombus (six studies, 390 patients) was 0.48 (95% CI 0. 29 to 0.79) with an event rate difference of -0.16 (95% CI 0.10 to -0. 42), whereas for antiplatelet agents (two studies, 112 patients) the o dds ratio was 1.43 (95% CI 0.04 to 56.8) with an event rate difference of 0.16 (95% CI -0.20 to 0.52). Conclusions. This analysis supports t he hypotheses that 1) mural thrombus after myocardial infarction poses a significantly increased risk of embolization, 2) the risk of emboli zation is reduced by systemic anticoagulation, and 3) anticoagulation can prevent mural thrombus formation. Thrombolytic therapy may prevent mural thrombus formation, but evidence for a similar benefit of antip latelet therapy is lacking.