In acute coronary syndromes, culprit plaques with vulnerable morphology were associated with larger intracoronary thrombus, which was associated with adverse clinical outcomes after percutaneous coronary intervention, suggesting that thrombus burden may represent the active and prognostically relevant expression of plaque vulnerability.
Key Findings
Results
Patients with high thrombus burden (HTB) had a significantly higher prevalence of plaque vulnerability than those with low thrombus burden.
Plaque vulnerability prevalence was 89.0% in HTB patients versus 75.3% in low TB patients (P=0.002).
Plaque vulnerability was defined by more than 2 features among thin-cap fibroatheroma, large lipid arc (>180°), microcalcifications, and macrophage infiltration.
The study included 300 patients with acute coronary syndromes undergoing percutaneous coronary intervention in the prospective, multicenter OPTICO-ACS study.
Optical coherence tomography (OCT) was used to assess underlying culprit lesion morphology.
Results
Vulnerable plaques were independently associated with high thrombus burden on multivariable analysis.
Adjusted odds ratio for vulnerable plaques predicting HTB was 2.5 (95% CI, 1.31–4.89; P=0.005).
This association remained significant after adjustment for potential confounders.
Angiographic thrombus burden was classified as high (HTB) or low using angiographic assessment.
Results
Patients with high thrombus burden had a significantly higher incidence of short-term major adverse cardiac events (MACE) compared to those with low thrombus burden.
Short-term MACE incidence was 12.3% in HTB patients versus 1.4% in low TB patients (P<0.001).
MACE was defined as cardiac death, nonfatal myocardial infarction, stroke, target vessel revascularization, or revascularization for angina.
Follow-up was conducted at a median of 12 months.
Results
Patients with high thrombus burden had a significantly higher incidence of long-term major adverse cardiac events compared to those with low thrombus burden.
Long-term MACE incidence was 22.1% in HTB patients versus 13.7% in low TB patients (P=0.04).
Median follow-up duration was 12 months.
The difference was statistically significant though smaller in magnitude than the short-term difference.
Results
High thrombus burden was identified as an independent predictor of long-term major adverse cardiac events in multivariable Cox regression analysis.
Adjusted hazard ratio for HTB predicting long-term MACE was 2.2 (95% CI, 1.23–3.98; P=0.008).
This association was independent of other clinical and angiographic variables.
Underlying plaque vulnerability did not independently predict long-term MACE in multivariable analysis.
Results
Underlying plaque vulnerability was not an independent predictor of long-term major adverse cardiac events in multivariable analysis.
Despite its strong association with HTB, plaque vulnerability itself did not reach independent prognostic significance for long-term MACE.
This finding suggests that thrombus burden mediates the prognostic relationship between plaque vulnerability and clinical outcomes.
The authors propose that 'TB may represent the active and prognostically relevant expression of plaque vulnerability, bridging morphological instability and clinical outcomes.'
Methods
The OPTICO-ACS study was designed as a prospective, multicenter study using OCT to assess culprit lesion morphology in acute coronary syndrome patients.
The study enrolled 300 patients with acute coronary syndromes undergoing percutaneous coronary intervention.
The study is registered at ClinicalTrials.gov (NCT03129503).
Both primary outcome (composite MACE) and secondary outcomes (individual MACE components and all-cause mortality) were assessed.
What This Means
This research investigated whether the amount of blood clot (thrombus) visible in a coronary artery during a heart attack is related to the underlying characteristics of the dangerous plaque that caused the blockage, and whether either factor predicts future heart problems. Using a specialized imaging technique called optical coherence tomography (OCT), researchers examined the coronary arteries of 300 heart attack patients and categorized them by how much clot was present (high versus low thrombus burden) and whether their plaques had features associated with instability, such as thin fibrous caps, large lipid deposits, microcalcifications, and macrophage infiltration.
The study found that patients with larger clots were much more likely to have unstable, 'vulnerable' plaques (89% vs. 75%), and that having a vulnerable plaque significantly increased the odds of also having a large clot. More importantly, patients with high thrombus burden had dramatically worse outcomes: they were about nine times more likely to experience a major adverse cardiac event (such as another heart attack, stroke, or need for repeat procedures) within the first year compared to those with low thrombus burden. Over longer follow-up, high thrombus burden remained a strong independent predictor of bad outcomes, while plaque vulnerability alone did not independently predict outcomes once thrombus burden was accounted for.
This research suggests that intracoronary thrombus burden may serve as a critical 'bridge' between the structural instability of a plaque and actual clinical harm — essentially, the clot is the active, measurable consequence of a vulnerable plaque and is what drives worse outcomes. These findings could have practical implications for how patients are risk-stratified and managed after a heart attack, potentially making thrombus burden assessment a useful tool for identifying patients who need more intensive monitoring or treatment following percutaneous coronary intervention.
Panuccio G, De Rosa S, Anwari E, Torella D, Meteva D, Ide S, et al.. (2026). Optical Coherence Tomography-Defined Vulnerable Plaques and Intracoronary Thrombus in Acute Coronary Syndromes: Insights From the OPTICO-ACS Program.. Journal of the American Heart Association. https://doi.org/10.1161/JAHA.125.047485