Identifying Risk Factors for Left Ventricular Thrombus in Patients with Ischemic Left
Ventricular Aneurysm Using Cardiac MRI
Left ventricular (LV) systolic dysfunction is associated with increased risk of thromboembolic
events.[1 ] However, clinical trials of routine anticoagulation for patients with depressed
LV systolic function have not supported universal anticoagulation in this population,[2 ]
[3 ] highlighting the need for better risk stratification to guide prophylactic strategies.
Ischemic LV aneurysm commonly occurs in the context of a non-perfused anterior wall
ST elevation myocardial infarction (MI) leading to reduced LV systolic function and
a hypokinetic, akinetic, or dyskinetic segment of the LV.[4 ] These aneurysms considerably increase the risk of LV thrombus (LVT) formation.[5 ] However, not all patients with ischemic LV aneurysm develop LVT and there is no
consensus for anticoagulation in this population. Determining the incidence, predictors,
and preventative strategies against LVT and systemic embolism in patients with chronic
LV aneurysm has remained controversial.[6 ] In the era of percutaneous coronary interventions, the incidence of post-infarction
LVT in patients with ischemic LV aneurysm varies between 5 and 15% when assessed by
transthoracic echocardiography and 12 and 27% using cardiac magnetic resonance imaging
(CMR).[7 ] The risk of thromboembolic events such as stroke with LVT can be as high as 11.2%
over a median follow-up of 38.7 months[8 ] with previous observational studies showing annual risk of 10 to 15% in untreated[4 ] versus 3.7% with majority of patients on anticoagulation.[9 ] Adding complexity to the issue, LVT in the setting of ischemic aneurysms is both
slow to resolve—with one serial CMR surveillance study showing persistent LVT 1 year
after proper anticoagulation in 37% of patients—and carries a high recurrence risk
even after initial resolution, with discontinuation of anticoagulation acting as a
contributing factor.[10 ]
This variability in the development of LVT and its risk of subsequent embolism suggest
that additional factors, such as the morphometric features of the aneurysm, may impact
the risk of LVT formation and embolism. In this context, the identification of novel
imaging-based risk factors could refine clinical decision-making, helping to determine
which patients with LV aneurysms are at greater risk for thrombus formation and might
benefit from prophylactic anticoagulation.
In this issue of Thrombosis and Haemostasis , Wu et al[11 ] offer new insights into this dilemma by identifying novel CMR-based risk factors.
In a retrospective analysis of 317 hospitalized patients with ischemic LV aneurysm
over 8 years, they examined the characteristics of ischemic left LV associated with
thrombus formation using delayed enhancement CMR and compared comorbidities between
88 patients with LVT and 229 without. Patients with LVT had lower LVEF, and greater
LV mass and volume. Interestingly neither history of MI nor usage of antiplatelet
or anticoagulation therapies was different between the two groups. On CMR, they identified
three significant risk factors associated with LVT: Wider aneurysm neck (odds ratio
[OR] 1.33 per 5 mm increment in neck size), a higher aneurysm shape index (ratio of
maximum length to neck width) (OR 1.63 per 20%, 95% CI 1.23–2.16), and a global late
gadolinium enhancement (LGE) extent greater than 50% (OR 6.58, 95% CI 3.04–14.27).
The authors should be congratulated for this timely and important contribution. This
study represents the largest CMR-based investigation to date on LVT in ischemic LV
aneurysms and highlights the growing role of advanced imaging in risk stratification
in addition to diagnosis.
Their findings introduce two key insights: First, the emphasis on aneurysm shape—indicated
by a higher shape index—challenges the traditional focus on aneurysm size alone. In
addition, a deeper, wider-necked aneurysm was found to correlate more strongly with
thrombus formation, suggesting that hemodynamic factors influenced by aneurysm morphology
are more critical in thrombus formation than previously recognized. Second, the strong
association between extensive LGE—a marker of myocardial fibrosis—and LV thrombus
risk, irrespective of LV systolic function. The finding that over half of the LVT
cases had a history of remote MI, up to 18 months prior, suggests that fibrosis is
a long-term thrombotic risk factor, not just an early post-MI concern. Besides these
MRI-based features, clinical correlates, such as history of heart failure, were also
more common in those with LVH. This aligns with the AHA Scientific Statement on the
Management of Patients at Risk for and with Left Ventricular Thrombus.[4 ]
Despite these advances, some unresolved issues remain. First, the study findings for
CMR features seem somewhat contradictory. On the one hand, a wider aneurysm neck is
reported to correlate with greater risk of LVT and yet on the other hand, a smaller
neck contributing to a higher shape index is also reported to increase the risk of
LVT. The possibilities include model overfitting and, alternatively, a statistical
interaction, such that a small neck is only predictive of greater risk in the context
of longer aneurysm longitudinal diameter.
Moreover, the study cohort lacks external validation and racial and ethnic diversity,
raising concerns about generalizability. This is important given reported ethnic differences
in the clinical outcomes of thromboembolism (hence, stroke) and bleeding.[12 ]
[13 ] Referral bias and variations in imaging protocols, particularly in LGE assessment,
may also impact reproducibility across clinical settings. Additionally, although certain
clinical characteristics have been linked to LV thrombosis, there is still no structured
framework, such as a scoring system, that integrates both imaging data and clinical
features. Last but not least, this study does not inform which LVT features directly
drive embolic events, which are the most consequential events warranting anticoagulation.
Therefore, to bridge this gap and translate these insights to practice, the results
of this study need external validation in large inclusive cohorts; a risk score may
be needed to identify patients at higher risk per clinical and imaging criteria, and
ideally, randomized trials to demonstrate net benefit in those deemed at high risk.
Nevertheless, the current study is a nice addition to the literature. Clinical and
imaging criteria can guide risk assessment and serve as a basis for shared decision-making
for preventative antithrombotic therapy as we await the generation of further high-quality
evidence ([Fig. 1 ]).
Fig. 1 Considerations for clinical risk factors, myocardial infarction (MI) characteristics,
and imaging characteristics that may impact the development of left ventricular thrombosis.
Careful assessment of these risk factors should lead to future development of validated
risk scores followed by targeted clinical trials to identify subgroups who benefit
most from preventative anticoagulation post-MI. CRP, C-reactive protein; LAD, left
anterior descending; LV, left ventricle; LVEF, left ventricular ejection fraction;
PCI, percutaneous coronary intervention; STEMI, ST-elevation myocardial infarction.
(Created in BioRender. Hashemi, A. (2025) https://BioRender.com/dy6y516 )
