Incidence of LV Thrombus After Anterior MI in the Modern Era
Incidence of LV Thrombus After Anterior MI in the Modern Era
Abstract & Commentary
By Andrew J. Boyle, MBBS, PhD
Source: Solheim S, et al. Frequency of left ventricular thrombus in patients with anterior wall myocardial infarction treated with percutaneous coronary intervention and dual anti-platelet therapy. Am J Cardiol 2010;106:1197-1200.
Dual anti-platelet therapy with aspirin and a thienopyridine, such as clopidogrel, is recommended after ST elevation myocardial infarction (MI). Prior to the era of potent anti-platelet therapy and aggressive infarct artery reperfusion strategies, left ventricular (LV) mural thrombus was seen relatively frequently after anterior MI. Coumadin is the recommended treatment for established LV thrombus and is recommended by some for the prevention of LV thrombus after anterior MI. However, there are few data about the frequency of LV thrombus following anterior MI from the modern era of rapid reperfusion and potent dual anti-platelet therapy. Consequently, current guidelines remain vague about the need for coumadin to prevent LV thrombus, in addition to dual anti-platelet therapy, for patients who have suffered anterior MI. Solheim and colleagues examined the echocardiograms and magnetic resonance images (MRI) from patients enrolled in the ASTAMI trial to determine the incidence of LV thrombus following anterior MI in the current era of rapid reperfusion and dual anti-platelet therapy. The ASTAMI trial randomized 100 patients in 1:1 fashion to intracoronary infusion of autologous bone marrow mononuclear cells vs. placebo after anterior MI that had been treated with percutaneous coronary intervention. Echocardiographic analysis was performed within the first 4 days post-MI and again at 3 months; MRI was performed at 18 days post-MI. Infarct size was assessed by serum creatine kinase (CK) measurements and by nuclear perfusion study performed 4 days post-MI.
Results: LV thrombus occurred in 15 patients (15%) following anterior MI, despite rapid reperfusion and dual anti-platelet therapy. Ten of these occurred in the first week, another four between 1 and 4 weeks post-MI, and the final one occurred between week 4 and 3 months post-MI. Comparing patients who had LV thrombus with those who did not, there were no differences in baseline clinical and demographic features. LV thrombus occurred in six patients randomized to cell therapy and nine patients randomized to placebo, suggesting no effect of the treatment on development of LV thrombus. However, patients who developed LV thrombus had larger infarcts. Peak CK was 6,128 micrograms/L in the LV thrombus group vs. 2,197 micrograms/L in those without LV thrombus (p < 0.01), and the percentage of the left anterior descending artery territory that was infarcted on nuclear scanning was 83% in those who developed LV thrombus vs. 64% in those who did not. Patients with peak CK levels in the highest quartile (> 4,900 micrograms/L) had a greater than 12-fold increased risk of developing LV thrombus. The authors conclude that the incidence of LV thrombus post-anterior MI in the current era is similar to previous times.
Commentary
There is little information to guide the use of coumadin after anterior MI to prevent LV thrombus formation. Solheim and colleagues show us that this clinical problem has not been solved with the advent of rapid reperfusion and dual anti-platelet therapy. Their data of 10% rate of detection of LV thrombus in hospital is in keeping with other small recent series: A 6.2% incidence (Am Heart J. 2009;157:1074-1080), and 10% incidence (J Thrombo Thrombolysis. 2000;10:133-136) also have been described. This study extends on these prior series by follow-up imaging at later time-points and also by using another complimentary modality, MRI. They show us that LV thrombus can develop after the initial hospitalization in a further 5% of patients. Furthermore, they show an association between larger infarcts and the development of LV thrombus, which is intuitive but has not been proven in the current era. However, there are some limitations to this study. Firstly, it a small (100 patient) retrospective study and, therefore, the results should be hypothesis-generating only. Secondly, the authors do not tell us the rate of peripheral embolism from the LV thrombus, nor their treatment strategy and its success rate. Future randomized, controlled trials of anticoagulation to prevent LV thrombus are needed.
Dual anti-platelet therapy with aspirin and a thienopyridine, such as clopidogrel, is recommended after ST elevation myocardial infarction (MI).Subscribe Now for Access
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