Scenario III – Thrombosis

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Summary

Scenario III – Thrombosis
Plaque rupture with arterial thrombosis is the underlying event in most cases of acute coronary syndrome (ACS). Although it is not necessary to perform OCT for the majority of PCIs performed in the setting of ACS, it is important to appreciate the excellent sensitivity of this imaging tool to detect intra-arterial thrombus. In certain cases, OCT can play an important role in guiding interventional decisionmaking with respect to thrombus burden and PCI. For example, in a patient with ACS and multiple lesions, OCT can be used to distinguish between a culprit lesion with fresh thrombus versus a chronic total occlusion. Prior to stent implantation, OCT can also assess the success of thrombus aspiration or disruption.

Case 4
Age: 51
Gender: Female
History: Hypertension and previous deep vein thrombosis. Presented with new onset, prolonged substernal chest pain at rest (CCS Class IV) and an elevated troponin I of 0.7, consistent with non-ST-segment myocardial infarction.

• Cardiac catheterisation demonstrated a hazy stenosis in the proximal RCA, with a tail-like filling defect on the downstream side of the lesion suggestive of thrombus (see Figure 4A).
• The operators began to perform PCI. After anticoagulation and wiring of the lesion, a manual thrombus aspiration device was used to reduce the thrombotic burden.
• Following thrombus aspiration, angiography revealed a marked resolution of the previously hazy stenosis with good distal flow (see Figure 4B).
• OCT of the proximal RCA was then performed to evaluate the extent of residual thrombus and the length of the underlying plaque prior to stent implantation (see Figure 4C). OCT revealed only a minimal residual thrombus burden and a minimal CSA of 2.9 mm².
• The lesion was then successfully stented with a 3.5 x 12 mm stent.
• OCT was performed again after stenting (not shown), revealing a well-apposed stent with minimal CSA of 8.5 mm².

In this PCI case, OCT confirmed adequate thrombus removal prior to stenting, which helped to guide stent size by assessing lesion length and vessel diameter and, finally, confirming optimal stent deployment post-PCI.

Case 5
Age: 33
Gender: Male
History: Coronary artery disease but no other cardiovascular risk factors. Presented with a four-hour history of severe chest pain and an electrocardiogram (EKG) consistent with an acute ST-segment elevation anterior myocardial infarction.

• Urgent cardiac catheterisation demonstrated complete occlusion of the proximal LAD (see Figure 5A).
• The operators began to perform PCI. After anticoagulation and wiring of the lesion, a manual thrombus aspiration device was used to reduce the thrombotic burden.
• Following thrombus aspiration, angiography suggested a marked resolution of the previously hazy stenosis, with good distal flow (see Figure 5B).
• OCT was then performed revealing a significant residual thrombus burden (see Figure 5C).
• On the basis of OCT, further manual aspiration thrombectomy was performed.
• Ultimately a 4.0 x 15 mm stent was placed across the lesion.
• Final OCT (not shown) revealed a well-apposed stent with no residual thrombus.
• OCT aided physician decision-making by identifying residual thrombus, guiding stent size and confirming stent deployment post-PCI.

Cases 4 and 5 highlight the use of OCT to define adequacy of thrombus removal prior to stent implantation. While the efficacy of this practice remains to be demonstrated in large clinical trials, the rationale is that distal embolisation is minimised by reducing the thrombus load at the time of stent deployment.