Surprisingly low incidence of left ventricular thrombosis in anterior ST‐segment elevation myocardial infarction

Abstract

We read with great interest the study by Ram et al. They concluded in their study that patients with left ventricular thrombus (LVT) postanterior ST-segment elevation myocardial infarction (STEMI) was associated with increased in-hospital thromboembolic events and length of hospital stay, but not in-hospital mortality or bleeding risks compared to those without LVT formation. 1 They also reported a low incidence of LVT in anterior STEMI, which is of interest given the considerable sample size. However, we are concerned if this may limit the generalizability of the results.In that study, presence of cardiac thrombosis (CAT) was identified using the International Classification of Diseases, 9th Revision, Clinical Modification (ICD9-CM) diagnosis code 429.79, which was then equated to LVT formation. However, we are unsure if this coding is likely to be representative of all anterior STEMI patients with LVT formation, as the exceedingly low incidence of LVT (0.4%, n = 649) was a surprising finding when compared to contemporary studies. For example, Shacham et al 2 reported an incidence of 4.0% (n = 18) in a similar population of post-anterior STEMI patients, while an analysis of our center's STEMI registry revealed an incidence of 3.0% (n = 120) for presence of LVT. Given that anterior STEMI is a known risk factor of LVT formation, 3 one would also expect its incidence to be much higher in this study. Lastly, CAT could be due to various forms of intra-cardiac thrombus besides LVT 4 such as left atrial thrombus or left atrial appendage thrombus, hence may not be entirely valid to equate them to LVT.The study draws its conclusion based on an analysis of data over a relatively long period from 2002 to 2014, hence we wonder if there might be significant heterogeneity present. Over the years, improvements in revascularization techniques, fast accessibility to primary percutaneous coronary intervention and advent of newer generation drug-eluting stents have been reported to improve rates of LV thrombus formation in post-STEMI patients. 5,6 Perhaps it may be interesting to compare the incidence and corresponding outcomes of STEMI patients with and without LVT across different eras of revascularization techniques. CONFLICTS OF INTERESTThe authors declare no potential conflict of interests. ORCIDAloysius Sheng-Ting Leow