Smart Drug-Eluting Stents

Drug-eluting stents (DES) revolutionised interventional cardiology by reducing in-stent restenosis from 20-30% with
bare-metal stents to 5-8% through controlled release of antiproliferative drugs. Yet current-generation DES release drug
at a fixed, pre-programmed rate regardless of the local vascular response -- delivering the same dose whether the vessel
is healing normally or developing neoatherosclerosis, whether the patient is diabetic or non-diabetic, and whether the
stent is deployed in a straight segment or a bifurcation. Smart drug-eluting stents represent the next evolution:
stimulus-responsive platforms that modulate drug release in response to local biological signals -- pH changes from
inflammation, shear stress variations from flow dynamics, enzymatic activity from matrix remodelling, or temperature
shifts from active inflammation. We present the Smart Stent Assessment Framework (SSAF), evaluating five smart DES
platforms -- pH-responsive polymer coatings, shear-activated nanoparticle reservoirs, enzyme-triggered biodegradable
layers, magnetically-actuated drug chambers, and electrochemically-controlled release systems -- across four coronary
scenarios (de novo lesion, bifurcation stenting, chronic total occlusion, and diabetic vasculopathy). Our Smart Stent
Performance Score (SSPS) measures drug release responsiveness, neointimal suppression efficacy, endothelialisation
preservation, mechanical integrity, and biocompatibility. pH-responsive polymer coatings achieve the highest SSPS
(0.922) through inflammation-triggered drug release that delivers antiproliferative therapy precisely when and where
neointimal hyperplasia initiates, while shear-activated nanoparticles achieve the best performance in bifurcation stenting
(neointimal suppression 0.940) where disturbed flow patterns drive focal restenosis.