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Histopathologic Characterization of Chronic Total Occlusions by Directional Atherectomy: The HIPACT Study
Haris Umer Usman1, Vincent Varghese, Sean Janzer
1Division of Interventional Cardiology and Endovascular Medicine, Einstein Medical Center, 5501 Old York Road, Philadelphia, PA 19141 USA. jcgeorgemd@gmail.com.
Insights
Histopathological analysis of femoropopliteal chronic total occlusions (CTOs) revealed that adventitia and thrombus content, along with lesion length, predict target-lesion revascularization (TLR). These findings aid in predicting clinical outcomes for CTOs.
Area of Science:
- Vascular biology and interventional cardiology
- Biomaterials science and tissue engineering
Background:
- Chronic total occlusions (CTOs) and long lesions in femoropopliteal arteries are linked to higher reocclusion rates and revascularization needs.
- Previous studies analyzed atherectomy samples but lacked correlation between CTO tissue characteristics and clinical outcomes.
- This pilot study aimed to predict clinical outcomes by assessing lesion characteristics.
Purpose of the Study:
- To correlate histopathological characteristics of femoropopliteal chronic total occlusions (CTOs) with clinical outcomes.
- To identify specific tissue components and lesion features that predict target-lesion revascularization (TLR).
Main Methods:
- Prospective observational study of patients with femoropopliteal CTOs.
- Optical coherence tomography (OCT)-guided crossing, directional atherectomy, and tissue sample collection.
- Histopathological analysis of excised tissue for adventitia, thrombus, and cellular/fibrous/lipid content, correlated with clinical outcomes.
Main Results:
- All 19 CTO lesions were successfully crossed without complications.
- Adventitial tissue (up to 57%) and thrombus (up to 34%) were prevalent in excised tissues.
- Target-lesion revascularization (TLR) at 6 months was 79%; elevated adventitia, thrombus, and lesion length (>15 cm) significantly correlated with TLR.
Conclusions:
- Histological analysis of adventitia and thrombus, combined with lesion length, can predict TLR incidence in femoropopliteal CTOs.
- This pilot study demonstrates the potential of lesion characterization for predicting clinical outcomes.
- Further validation in larger studies is necessary to confirm these predictive findings.
Background:
Chronic total occlusions (CTOs) and long lesions have been associated with higher reocclusion rates in femoropopliteal arteries and increased need for revascularization. While several studies have analyzed atherectomy samples, no study to date has correlated the tissue characteristics of CTOs with clinical outcomes. This pilot study assessed lesions in order to predict clinical outcomes based on lesion characteristics.
Methods:
Patients presenting with femoropopliteal (FP) CTO lesions, including in-stent restenosis and de novo lesions, were enrolled in a prospective, observational study. With patient consent, CTOs were crossed using a crossing catheter guided by optical coherence tomography (OCT) imaging. Atherectomy was performed with a directional atherectomy device and tissue samples were collected and subjected to histopathological analysis for the presence of adventitial tissue and thrombus, and the amounts of hypercellular cells, fibrocellular material, fibrous tissue, and lipid-rich tissue in the excised tissue were measured. The compiled data were correlated with clinical outcomes, as recorded at each patient's clinical follow-up visit.
Results:
All CTO lesions (n = 19) were successfully crossed, with no dissections or perforations. Adventitial tissue was found in excised tissue from all 19 lesions (up to 57% of total lesion area), and thrombus was found in 15 lesions (up to 34% of total lesion area). The amount of hypercellular cells, fibrocellular material, fibrous tissue, and lipid-rich tissue present in the excised tissue did not correlate with the incidence of target-lesion revascularization (TLR). At 6-month follow-up exam, 79% of the treated lesions had TLR. Risk of TLR was assessed based on weighted risk of each variable; the results determined that occurrence of TLR was associated with elevated levels of adventitia and thrombus in the lesions and with lesions >15 cm in length. There was a significant correlation (P<.05) between TLR and the lesion characterization as set forth in the present study.
Conclusions:
Pairing the histological analysis, including content of adventitia and thrombus, with lesion length and binary clinical outcomes enabled the predictive incidence of TLR in this pilot study. Further work needs to be conducted to validate these findings in larger studies.
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