Safety, efficacy and OCT findings of polymer-free versus biodegradable-polymer drug-eluting stents in patients undergoing percutaneous coronary intervention: a systematic review and meta-analysis

Background Durable drug-eluting stents (DES) have been associated with persistent vascular inflammation, delayed endothelial healing, and late adverse events such as stent thrombosis. Biodegradable polymer DES (BP-DES) were developed to reduce these risks as the polymer biodegrades after the drug release thus reducing polymer exposure. Whereas polymer-free DES (PF-DES) depends on alternative drug-release mechanisms to avoid polymer-related adverse effects. Although both types may reduce long-term risks compared to the durable DES, there are concerns regarding the efficacy of the PF-DES due to variable drug-release mechanisms. Purpose This systematic review and meta-analysis aim to evaluate clinical safety and efficacy and OCT-assessed vascular healing between PF-DES and BP-DES. Methods We systematically searched PubMed, Web of Science (WOS), and Scopus. Inclusion criteria comprised randomized controlled trials comparing Polymer Free DES and Biodegradable Polymer DES in patients undergoing percutaneous coronary interventions. We excluded cohort studies, case reports, editorials, conference abstracts, and animal studies. Cochrane’s ROB 2.0 tool assessed RCTs quality, and RevMan software (5.4) performed the meta-analysis. Results Our analysis included eight RCTs, totaling 6,312 patients, with 3,095 in the PF-DES group and 3,217 in the BP-DES group. Target lesion revascularization (TLR) occurred in 114 patients (3.71%) in the PF-SES group and 75 patients (2.41%) in the BP-DES group, showing statistically significant differences between the groups (RR =1.55, 95% CI = 1.16 to 2.06, p = 0.003). There were no significant differences between the two groups in Target vessel revascularization (TVR) (RR = 1.08, 95% CI = 0.85 to 1.35, p = 0.54), definite stent thrombosis (RR = 1.26,95% CI = 0.43 to 3.68, p = 0.67), cardiac death (RR = 1.00, 95% CI = 0.73 to 1.36, p = 0.99), and OCT-findings including uncovered struts (RR = 0.94, 95% CI = 0.61 to 1.44, p = 0.77) and malapposed struts (RR = 1.11, 95% CI= 0.82 to 1.49, p = 0.51). Secondary endpoints also showed no significant differences between the two groups; All-cause mortality (RR = 1.03, 95% CI = 0.80 to 1.31, p = 0.83), Target-lesion related myocardial infarction (RR =1.08, 95% CI = 0.87 to 1.34, p = 0.48), and overall stent thrombosis (RR = 0.52, 95% CI = 0.20 to 1.37, p = 0.19). Conclusion The use of PF-DES resulted in higher rates of Target lesion revascularization (TLR) compared to BP-DES, but not TVR, definite stent thrombosis, cardiac death or OCT-assessed vascular healing where they had similar percentages of uncovered and malapposed struts. These findings suggest that PF-DES might be less efficacious compared to BP-DES although it had similar safety profile and vascular healing characteristics. Future randomized clinical trials are therefore needed to further assess its safety and efficacy and further establish its value for the practice.