Purpose: The prognostic implications of calcified versus non-calcified tissue protrusions (TPs) following stent implantation remain undetermined. This study aimed to evaluate the differential clinical outcomes associated with calcified and non-calcified TP morphologies.
Patients and Methods: Employing intravascular ultrasound (IVUS), we identified calcified TPs as calcium fragment extrusions permeating the stent struts, while non-calcified TPs were characterized as plaque and/or thrombus extensions through the stent into the arterial lumen. The primary endpoint encompassed target lesion failure (TLF), comprising cardiac death, target vessel myocardial infarction, clinically driven target lesion revascularization (TLR), or stent thrombosis, assessed in patients with a follow-up period exceeding one year.
Results: Of 1033 patients subjected to pre- and post-intervention IVUS, 62 exhibited calcified TPs (6.0%), and 279 presented non-calcified TPs (27.0%), forming the basis of this analysis. Multivariable linear regression indicated calcified nodules as a significant predictor of calcified TP [Odds Ratio (OR) 2.47; 95% Confidence Interval (CI) 2.33 to 2.62; P < 0.001], with ST-segment elevation myocardial infarction emerging as an inverse correlate [OR 0.82; 95% CI 0.73 to 0.93; P = 0.004]. Two-year data revealed a higher incidence of TLF in patients with calcified TPs versus their non-calcified counterparts (11.3% vs 2.2%, P < 0.001), and a marked increase in clinically driven TLR (9.7% vs 1.4%, P < 0.001). Calcified TPs were independently correlated with increased TLF risk in the adjusted model [Hazard Ratio (HR) 2.47; 95% CI 1.17 to 5.16; P = 0.027].
Conclusion: After drug-eluting stent implantation, IVUS-identified calcified TPs correlate with adverse clinical outcomes compared to non-calcified TP formations.

Keywords: percutaneous coronary intervention, intravascular ultrasound, tissue protrusion, prognosis