Drug-eluting stents versus bare-metal stents for treatment of bare-metal in-stent restenosis

Evolutionary perspective of drug eluting stents: from thick polymer to polymer free approach

Background

Introduction of Bare Metal Stents (BMS) was itself a revolutionary step in the history of the medical industry; however, Drug Eluting Stents (DES) maintained its superiority over BMS in every aspect from restenosis rate to late lumen loss. The reason behind the magnanimous position of the DES in the stent market is the degree of improvement with which it evolves. New and better stents come into the market every year, surpassing their predecessors by many folds.

Literature review

This review paper discusses the journey of DES with supporting clinical trials in detail. In the first generation, there were stainless-steel stents with thicker coatings. Although they had superior results compared to BMS, there was still room for improvement. Afterward came the second-generation stents, which had superior metal platforms with thinner struts and thin coatings. The drugs were also changed from Paclitaxel and Sirolimus to Zotrolimus and Everolimus. These stents performed best; however, there was an issue of permanent coating, which remained intact over the stent surface after complete drug elution and started to cause issues in longer-term studies. Hence, an improved version of DES was introduced to these permanent coatings called the third generation of drug eluting stents, which initially utilized biodegradable polymer and ultimately moved towards polymer free drug coatings. This generation has introduced a unique amalgam of technologies to achieve its polymer free coatings; however, researchers have numerous prospects of growth in this field. This review paper highlights the major coups of stent technology evolution from BMS to DES, from thick polymeric coatings to thin coatings and from durable polymers to polymer free DES.

Conclusion

In conclusion, though the medical industry promptly accepted BMS as the best treatment option for cardiovascular diseases; however, DES has provided even better results than BMS. In DES, the first and second generation has ruled the technology for many years and are still on the shelves. Still, the issues aroused due to durable polymer shifted the attention towards biodegradable drug eluting stents, the third generation growing rapidly. But the scientific community has not restricted themselves and is investigating bioresorbable stents that completely eliminate the polymer intervention in drug eluting stent technology.

Evaluation of relationship between common carotid artery intima-media thickness and coronary in-stent restenosis: A case-control study

Aim

The study was intended to evaluate relationship of common carotid artery intima-media thickness (CIMT) with coronary in-stent restenosis (ISR) and to assess clinical profile of patients to determine the predictors of coronary ISR.

Methods

This was a single-center, case-control study performed between December 2012 and February 2015 in India. The study population consisted of PCI-treated patients with ISR (n = 32) and those without any post-PCI symptoms at least 6 months prior to the study period (n = 40). Quantitative coronary angiography was performed in patients to determine ISR.

Results

Average CIMT for cases and controls was 0.96 ± 0.23 and 0.66 ± 0.09 mm (OR = 57, p < 0.001), respectively. CIMT was <0.8 mm in 25% of cases and 95% of controls. On multivariate analysis, presence of hypertension (OR = 10.79, p = 0.026) and higher stent diameter (OR = 14.87, p = 0.039) were independently associated with increased presence of ISR. CIMT <0.8 mm (OR = 0.03, p = 0.025), STEMI (OR = 0.03, p = 0.004), and estimated glomerular filtration rate >50 ml/min (OR = 0.005, p = 0.014) were independently associated with lower presence of ISR.

Conclusions

Elevated CIMT appears to be an independent risk indicator for increased ISR. As CIMT is a non-invasive parameter, post-PCI follow-up measurements of CIMT in routine clinical practice will provide potential benefits to predict the restenosis rates.

“Bare Metal” Stent Placement Complications: Interventional Treatment

The rapid implementation of stents in standard practice and expansion of the indication for their utilization also introduced a new problem: in-stent restenosis. Management of patients with restenosis after stent implantation is still considered an important clinical problem. Although balloon angioplasty is still one of the prefered strategies that provide satisfactory results and a low incidence of complication, repeat stenting with “drug eluting” stents or “drug balloon” angioplasty become a very atractive methods of treatment for selected lesions and patients.

Cost-effectiveness modelling of percutaneous coronary interventions in stable coronary artery disease

The objective of this study is to develop a cost-effectiveness model comparing drug eluting stents (DES) vs bare metal stent (BMS) in patients suffering of stable coronary artery disease. Using a 2-years time horizon, two simulation models have been developed: BMS first line strategy and DES first line strategy. Direct medical costs were estimated considering ambulatory and hospital costs. The effectiveness endpoint was defined as treatment success, which is the absence of major adverse cardiac events. Probabilistic sensitivity analyses were carried out using 10000 Monte-Carlo simulations. DES appeared slightly more efficacious over 2 years (60% of success) when compared to BMS (58% of success). Total costs over 2 years were estimated at 9303 € for the DES and at 8926 € for bare metal stent. Hence, corresponding mean cost-effectiveness ratios showed slightly lower costs (P < 0.05) per success for the BMS strategy (15520 €/success), as compared to the DES strategy (15588 €/success). Incremental cost-effectiveness ratio is 18850 € for one additional percent of success. The sequential strategy including BMS as the first option appears to be slightly less efficacious but more cost-effective compared to the strategy including DES as first option. Future modelling approaches should confirm these results as further comparative data in stable coronary artery disease and long-term evidence become available.

Impact of routine angiographic follow-up after percutaneous coronary intervention with drug-eluting stents in the SPIRIT III randomized trial at three years

Routine angiographic follow-up after bare-metal stent implantation has been associated with an increase in coronary revascularization. The impact of angiographic follow-up after drug-eluting stent placement remains poorly characterized. The prospective, randomized, single-blinded SPIRIT III trial assigned patients to the everolimus-eluting stent or the paclitaxel-eluting stent (PES). Major adverse cardiovascular events (cardiac death, myocardial infarction, and ischemia-driven target lesion revascularization [ID-TLR]) at 3 years were assessed by angiographic versus clinical-only follow-up at 8 months ± 28 days and a landmark survival analysis from 9 months to 3 years. Of 1,002 patients, 564 patients were assigned to angiographic follow-up at 8 months ± 28 days and 438 patients underwent clinical follow-up alone. Three-year major adverse cardiovascular event rates were 10.6% in the angiographic group and 12.0% in the clinical follow-up group (p = 0.64). Ischemia-driven revascularization increased twofold at 9 months, but no difference was noted in ID-TLR for either device. Non-ID-TLR was significantly higher in patients in the angiographic group (4.5% vs 1.0%, p = 0.002), a difference resulting from PES (9.1% vs 0.7%, p = 0.0007) rather than everolimus-eluting stent (2.2% vs 1.1%, p = 0.36) treatment. The landmark analysis showed no significant differences between the angiographic and clinical follow-up groups from 9 months to 3 years of major clinical outcomes. In conclusion, routine angiographic follow-up in SPIRIT III did not increase rates of ID-TLR compared to clinical follow-up alone. Despite higher nonischemia-driven revascularization rates with angiographic follow-up of patients with PESs, none of the safety end points were adversely affected.

Recurrent angina after coronary angioplasty: mechanisms, diagnostic and therapeutic options

Recurrent angina in patients who underwent percutaneous coronary intervention is defined as recurrence of chest pain or chest discomfort. Careful assessment is recommended to differentiate between non-cardiac and cardiac causes. In the case of the latter, recurrent angina occurrence can be related to structural ('stretch pain', in-stent restenosis, in-stent thrombosis, incomplete revascularization, progression of coronary atherosclerosis) or functional (coronary micro-vascular dysfunction, epicardial coronary spasm) causes. Even though a complete diagnostic algorithm has not been validated, ECG exercise testing, stress imaging and invasive assessment of coronary blood flow and coronary vaso-motion (i.e. coronary flow reserve, provocation testing for coronary spasm) may be required. When repeated coronary revascularization is not indicated, therapeutic approaches should aim at targeting the underlying mechanism for the patient's symptoms using a variety of drugs currently available such as beta-blockers, calcium-channel blockers, ivabradine or ranolazine.

Restenosis after PCI. Part 2: prevention and therapy

The techniques and materials used during percutaneous coronary intervention have advanced considerably over the past 3 decades, yet restenosis remains one of the major drawbacks of this procedure. Many innovative technologies, including drug-eluting stents, with or without specific polymers, and fully biodegradable stents have been and continue to be developed in the search for a safe and effective antirestenosis therapy. Remarkable advances in stent design and nanoparticle delivery systems ('nanovehicles') have already fueled revolutionary changes in the prevention and treatment of in-stent restenosis. In this Review we provide an overview of the latest innovations for optimizing outcomes of coronary stenting, and up-to-date information about prevention and treatment of in-stent restenosis.

[Update in interventional cardiology]

This article contains a detailed review of the most important studies on interventional cardiology reported in either publications or presentations. With regard to coronary interventions, ST-elevation myocardial infarction is highlighted because of the ongoing substantial expansion in primary angioplasty programs. Drug-eluting stents, especially new-generation stents, continue to be the focus of numerous studies. Clinical outcomes in diabetic patients with left main coronary artery or multivessel disease are also dealt with by much research. In addition, intracoronary diagnostic techniques, particularly optical coherence tomography, is reviewed. Finally, there is increasing interest in the percutaneous treatment of structural heart disease, particularly percutaneous aortic valve implantation.