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.