Histopathologic and physiologic effect of overlapping vs single coronary stents: impact of stent evolution

Bare metal stents (BMS) and drug eluting stents (DES) have been deployed in single and overlap configurations, the latter mostly to cover long-lesions. Both type of stents in overlap configuration increases the risk of adverse events.We present the rationale for either BMS or DES usage utilizing both preclinical and clinical studies for the use of single vs. overlapped stents. Further, employing experimental and pathological studies, we discuss the disadvantages of stent overlapping vs. single stenting and propose that vessel injury, local blood flow disturbance, higher drug/polymer dose are mechanisms leading to poor clinical outcomes including in-stent restenosis (ISR), delayed arterial healing, thrombosis, and hypersensitivity reactions. We also explore whether newer generation (2nd generation) DES with reduced strut thickness, optimized drug release profiles, better polymer biocompatibility minimize the disadvantages of stent overlap seen in 1st generation DES. Finally, we examine the reasons why fully bioabsorbable scaffolds resulted in increased adverse events.DES innovations have minimized the risk of ISR and repeat revascularization. In contradistinction to 1st generation DES, major adverse cardiac events (MACE) is similar between single and overlapped stents in 2nd generation DES, suggestion stent design play an important role in clinical outcomes.