Transthoracic Echocardiography versus Cardiac Magnetic Resonance Imaging for the Diagnosis of Left Ventricular Thrombus: An Updated Systematic Review and Meta-Analysis

Background Left Ventricular Thrombus (LVT) is a significant complication of myocardial infarction (MI), linked to higher morbidity and mortality due to the risk of systemic embolization and stroke. Early detection of LVT is crucial for prompt initiation of anticoagulation therapy. This meta-analysis compares the diagnostic accuracy of Cardiac Magnetic Resonance (CMR) with Transthoracic Echocardiography (TTE) in identifying LVT. Methods Following PRISMA guidelines, we conducted a systematic review and meta-analysis. Databases searched included PubMed, Cochrane, CNKI, Scopus, LILACS, Web of Science, Google Scholar, EMBASE, and CINAHL. Random-effects meta-analyses were performed in R (v3.4.3), reporting pooled proportions or AUC with 95% confidence intervals. Heterogeneity was assessed using the I2 statistic. Results Eighteen studies involving 3,478 participants met the inclusion criteria. Most studies contributed to the primary analysis of TTE performance using CMR as the standard of reference. Head-to-head comparison was substantially smaller and included only five studies. In the head-to-head analysis using an independent reference standard, CMR demonstrated significantly higher sensitivity (70.5%, 95% CI: 0.554 to 0.822) and specificity (99.2%, 95% CI: 0.983 to 0.997) in detecting LVT compared to TTE (sensitivity 31.8%, 95% CI: 0.252 to 0.391; specificity 96.3%, 95% CI: 0.929 to 0.981), these estimates should be interpreted in the context of most included studies using a different CMR acquisition protocol, specifically LGE-CMR, as the reference standard, rather than an independent imaging modality or pathological confirmation. The area under the curve (AUC) for CMR was 0.985, indicating superior diagnostic performance over TTE, which had an AUC of 0.59. Heterogeneity was significant for TTE (I2 = 75.8%) but low for CMR (I2 = 0.0%), highlighting the consistency of CMR's diagnostic accuracy. Publication bias was assessed using funnel plots, showing a low likelihood of bias in the included studies. Conclusion CMR may provide a diagnostic advantage over TTE for LVT detection, particularly in high-risk patients or when TTE is negative or inconclusive. However, this apparent advantage is limited by the lack of a robust independent reference standard and by the predominance of historical studies using heterogeneous and often non-optimized echocardiographic protocols. Further contemporary studies using independent validation standards are needed.