Fractal analysis of left ventricular trabeculae in post-STEMI: from acute to chronic phase
Ruo-Yang Shi1,2, Rui Wu1, Jinjun Ran3
1Department of Radiology, School of Medicine, Ren Ji Hospital, Shanghai Jiao Tong University, No. 160, Pujian Road, Shanghai, 200127, China.
Insights
In patients with ST-segment elevation myocardial infarction (STEMI), decreasing left ventricular trabecular complexity, measured by global fractal dimension (FD), independently predicts major adverse cardiovascular events (MACE). A lower subacute phase global FD indicates a higher risk.
Area of Science:
- Cardiovascular Imaging and Diagnostics
- Cardiac MRI
- Myocardial Infarction Research
Background:
- Assessing long-term outcomes after ST-segment elevation myocardial infarction (STEMI) is crucial.
- The role of left ventricular (LV) trabecular complexity changes in predicting adverse events post-STEMI is not fully understood.
- Cardiac Magnetic Resonance (CMR) offers detailed insights into cardiac structure and function.
Purpose of the Study:
- To investigate the temporal changes in LV trabecular complexity using fractal dimension (FD) after acute STEMI.
- To determine the correlation between these changes in FD and the occurrence of major adverse cardiovascular events (MACE).
- To evaluate FD as an independent predictor of MACE beyond established risk factors.
Main Methods:
- Retrospective analysis of 200 patients with acute STEMI treated with primary percutaneous coronary intervention (pPCI).
- CMR scans were performed in the acute (≤7 days), subacute (1 month), and chronic (6 months) phases post-pPCI.
- Global, infarct, and remote region LV trabecular fractal dimensions (FD) were calculated and analyzed for association with MACE using Cox regression.
Main Results:
- A significant decrease in global FD was observed over time post-STEMI (p < 0.0001).
- Patients who experienced MACE showed a more pronounced decline in global FD (p < 0.001).
- Global FD at the subacute phase independently predicted MACE (HR 0.89, p = 0.01), with values below 1.26 indicating heightened risk.
Conclusions:
- Global FD, a measure of LV trabecular complexity, decreases after STEMI, particularly in patients with subsequent MACE.
- Subacute phase global FD and the change in global FD from acute to subacute phase are associated with MACE.
- Global FD serves as an independent predictor of MACE, offering prognostic value beyond traditional clinical and CMR parameters.
Purpose:
The temporal evolution of ventricular trabecular complexity and its correlation with major adverse cardiovascular events (MACE) remain indeterminate in patients presenting with acute ST elevation myocardial infarction (STEMI).
Methods:
This retrospective analysis enrolled patients undergoing primary percutaneous coronary intervention (pPCI) for acute STEMI, possessing cardiac magnetic resonance (CMR) data in the acute (within 7 days), subacute (1 month after pPCI), and chronic phases (6 months after pPCI) from January 2015 to January 2020 at the three participating sites. Fractal dimensions (FD) were measured for the global, infarct, and remote regions of left ventricular trabeculae during each phase. The potential association of FD with MACE was analyzed using multivariate Cox regression.
Results:
Among the 200 analyzed patients (182 men; median age, 61 years; age range, 50-66 years), 37 (18.5%) encountered MACE during a median follow-up of 31.2 months. FD exhibited a gradual decrement (global FD at acute, subacute, and chronic phases: 1.253 ± 0.049, 1.239 ± 0.046, 1.230 ± 0.045, p < 0.0001), with a more pronounced decrease observed in patients subsequently experiencing MACE (p < 0.001). The global FD at the subacute phase correlated with MACE (hazard ratio 0.89 (0.82, 0.97), p = 0.01), and a global FD value below 1.26 was associated with a heightened risk.
Conclusion:
In patients post-STEMI, the global FD, serving as an indicator of left ventricular trabeculae complexity, independently demonstrated an association with subsequent major adverse cardiovascular events, beyond factors encompassing left ventricular ejection fraction, indexed left ventricular end-diastolic volume, infarct size, heart rate, NYHA class, and post-pPCI TIMI flow.
Critical Relevance Statement:
In patients who have had an ST-segment elevation myocardial infarction, global fractal dimension, as a measure of left ventricular trabeculae complexity, provided independent association with subsequent major adverse cardiovascular event.
Key Points:
• Global and regional FD decreased after STEMI, and more so in patients with subsequent MACE. • Lower global FD at the subacute phase and Δglobal FD from acute to subacute phase were associated with subsequent MACE besides clinical and CMR factors. • Global FD at the subacute phase independently correlated with MACE and global FD value below 1.26 was associated with higher risk.
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