Screening algorithm
In patients with uncomplicated anterior MI it is advised to carry out a LVT screening before discharge. Recently, a TTE-based wall motion screening algorithm for LVT has been proposed, able to assesses the extent of apical wall-motion abnormalities using the 17-segment model. Apical LV wall motion score is then calculated on non-contrast echo by summing segmental scores within the apical LV and true apex (total of 5 segments). An apical wall motion score ≥5 can identify patients with a high likelihood of LVT, thus to be referred eventually for CE-CMR with a high diagnostic yield, regardless of LV global contractile function.16 Therefore, given cost containment, a pre-discharge TTE-based screening approach should be implemented: contrast-enhanced TTE could be performed instead of CE-CMR in all patients with high-risk apical wall motion score, especially in patients with poor ultrasound windows, and a CE-CMR could be reserved only when contrast-enhanced echo is non-conclusive. However, considering that the hospital stay of patients with uncomplicated MI has declined substantially in recent years26 and therefore is shorter than the time needed for a LVT to be detected26, it may be reasonable to repeat a TTE during the second week in patients with high-risk apical wall motion abnormality without LVT on initial imaging.
The alternative approach is to perform CE-CMR to all patients with high-risk apical wall motion score at non-contrast TTE. Of note, no specific screening pathway after anterior MI has been prospectively validated, therefore further validation before widespread application is required. A recent single-center retrospective case-match study showed that, despite contemporary antithrombotic treatment, a LVT detected by CE-CMR, but not by contrast TTE, is associated with a similar 4-fold long-term higher risk of embolism compared with matched non-LVT patients.27 However, this study evaluated a heterogeneous cohort where only one-third of patients had a previous MI with a severely reduced ejection fraction. Because of the retrospective nature of the study, referral bias was inevitable and it was not feasible to obtain reliable measures of the efficacy of anticoagulation, such as the time in therapeutic range, in all LVT patients. Therefore, to address all these limitations, more studies are needed specifically comparing screening strategies based on contrast TTE or CE-CMR for detection of LVT in patients with recent anterior MI.