OCT insights of thrombus extraction by stent-retriever thrombectomy (SRT) and manual aspiration (MA): Insights from RETRIEVE AMI trial
Reported from TCT 2025
Aaysha Cader provides her take on sub-analyses of the RETRIEVE AMI trial presented by Jason Leo Walsh at TCT 2025, in San Francisco.
Background
The RETRIEVE AMI (stent-retriever thrombectomy for thrombus burden reduction in patients with acute myocardial infarction) trial, presented as hotline at EuroPCR 2025, assessed the safety and efficacy of primary PCI with stent-retriever thrombectomy (SRT) vs export manual aspiration (MA) vs no thrombus modification (i.e. only stenting) in STEMI patients with large thrombus burden (LTB). LTB was defined as TIMI thrombus grade ≥ 4 and intracoronary thrombus volume was quantified with OCT1.
This single-center study (n = 81) conducted at the Oxford Heart Centre enrolled 81 STEMI patients with LTB. SRT was performed in 26 cases (one crossover), MA in 27 and no thrombus modification in 27 cases. The trial results showed that both SRT and MA significantly reduced pre-stent thrombus burden (SRT: 12.8 %; IQR: 4.4 %-21.5 %; P = 0.016 and MA: 13.0 %; IQR: 3.8 %-19.4 %; P = 0.003) compared to no modification, with no device-related clinically relevant arterial and no differences in MACCE at 6-months between SRT and MA devices.
Two OCT sub-analyses of the RETRIEVE AMI trial were presented at TCT 2025 by Jason Walsh:
A. Validation of an optical coherence tomography estimate of extracted coronary thrombus volume and a comparison of thrombus type extracted by stent-retriever versus manual aspiration in ST-elevation myocardial infarction2
In this sub-study, the investigators set out to validate an OCT-derived precise quantification of thrombus volume and comparison of thrombus type extracted by each pf the two devices, SRT vs MA.
Methodology:
The extracted thrombus volume for MA and SRT was estimated as the Δ between pre- and post-thrombus modification OCT measurements. The Δ thrombus on OCT was validated as an estimate of extracted thrombus volume. Further, the macroscopic thrombus phenotype extracted by SRT was compared to MA, and described.
Standardised thrombus photographs were acquired and analyzed in ImageJ. Thrombus area (mm2) on OCT was correlated with Δ thrombus volume (mm³) on OCT using Spearman’s rank correlation.
Results:
Extracted thrombus area correlated strongly with Δ thrombus volume for both SRT (n = 17, ρ = 0.91, p < 0.001) and MA (n = 13, ρ = 0.69, p = 0.01). In terms of thrombus phenotype, all SRT extracted thrombi were classified as red and MA extracted thrombi were 38 % red, 31 % white, and 31 % mixed.
Interpretation:
Δ thrombus volume on OCT correlates strongly with extracted thrombus area, providing a useful and more precise parameter to estimate extracted coronary thrombus volume, in preference to semiquantitative angiographic scores.
Given the preferential extraction of red thrombi by SRT, the study provides some insight into possible options for selection of thrombus modification, based on red vs white thrombus sub-type on OCT, which could be relevant as red-cell rich thrombi predict worse outcomes. important to note that this was an exploratory sub-analysis of a proof-of-concept trial and no downstream clinical outcomes for these parameters were tested.
B. Presence of plaque erosion predicts effective thrombus modification in STEMI with high thrombus burden: insights from the RETRIEVE AMI Trial3
Background:
This exploratory sub-analysis of RETRIEVE AMI aimed to identify predictors of successful thrombus burden reduction.
Methodology:
In order to identify predictors of thrombus burden reduction (Δ thrombus burden, %), multivariate linear regression was done, evaluating relevant demographic, procedural and OCT variables: lesion location, patient demographics, comorbidities, thrombectomy technique, presentation mechanism (erosion vs. plaque rupture), baseline thrombus burden, and symptom-to-reperfusion time.
Results:
The predictors of thrombus burden reduction identified were: baseline thrombus burden (coefficient: 1.4, p = 0.001), RCA lesion location (coefficient: 24.0, p = 0.04), and plaque erosion (coefficient: 30.0, p = 0.02). Notably, a a significantly greater reduction in thrombus burden was seen in plaque erosion (73.5 %; 39.7–83.9 %) as compared to plaque rupture (73.5 % vs 29.8 %; p = 0.02).
Interpretation:
Given the worse outcomes associated with LTB and the uncertainty on optimal thrombus reduction strategies in this subset of STEMI patients, this sub-analysis, albeit exploratory suggests that intracoronary imaging by OCT can potentially guide clinicians in identifying large thrombus burden at primary PCI and potentially help select thrombus extraction strategy, based on OCT phenotypes of thrombus and plaque morphology.
However, limitations include its small sample size, and while the primary trial design was randomised, biases cannot be ruled out in this exploratory sub-analysis. Further prospective studies in larger patient populations, incorporating OCT-based plaque and thrombus characteristics and powered for clinical endpoints are warranted.
References
- Kotronias RA, Walsh JL, Andreaggi S, Portolan L, Maino A, Marin F, et al; OxAMI and RETRIEVE AMI Investigators. Stent-Retriever Thrombectomy in STEMI With Large Thrombus Burden: The RETRIEVE AMI Randomized Trial. JACC Adv. 2025 Jul;4(7):101893. doi: 10.1016/j.jacadv.2025.101893. Epub 2025 Jun 23. PMID: 40555011; PMCID: PMC12226358.
- TCT-1076 Validation of an optical coherence tomography estimate of extracted coronary thrombus volume and a comparison of thrombus type extracted by stent-retriever versus manual aspiration in ST-elevation myocardial infarction. Available at: https://www.jacc.org/doi/10.1016/j.jacc.2025.09.1280 [Presented at TCT 2025]
- TCT-1089 Presence of Plaque Erosion Predicits Effective Thrombus Modification in STEMI with High Thrombus Burden: Insights from the RETRIEVE AMI Trial. Available at : https://www.jacc.org/doi/10.1016/j.jacc.2025.09.1295 [Presented at TCT 2025]
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