Lipoprotein(a) and Optical Coherence Tomography–Based Characterization of In-Stent Restenosis: A Case Series

Introduction: In-stent restenosis (ISR) remains a frequent cause of stent failure after percutaneous coronary intervention (PCI) and continues to contribute substantially to repeat coronary revascularization. Intracoronary optical coherence tomography (OCT) provides high-resolution imaging that enables detailed characterization of ISR mechanisms, thereby facilitating individualized treatment strategies. Lipoprotein(a) is a well-established risk factor for coronary artery disease, and emerging evidence suggests a potential association between elevated Lp(a) levels and ISR. Methods: We present a case series of three patients who developed symptomatic ISR following drug-eluting stent implantation. All patients underwent comprehensive clinical evaluation and coronary angiography, followed by intracoronary OCT imaging to identify the underlying ISR mechanisms, including neointimal hyperplasia, neoatherosclerosis, and stent-related mechanical factors. Serum Lp(a) levels were measured in all cases. Treatment strategies were selected based on OCT findings and individual clinical characteristics. Results: OCT imaging revealed distinct ISR mechanisms across the three cases. Elevated Lp(a) levels were observed in all patients, although the degree of elevation varied considerably. OCT-guided, mechanism-specific treatment strategies were successfully implemented in each case, resulting in optimal angiographic outcomes and clinical improvement at the one-month follow-up. Conclusions: This case series highlights the value of OCT in elucidating heterogeneous mechanisms of ISR and guiding individualized treatment approaches. Elevated Lp(a) levels were observed in all cases; however, given the descriptive nature and small sample size of this report, no conclusions regarding causality or clinical association can be drawn.