11.1

Stent Type

Restenosis rates after chronic total occlusion (CTO) stenting can be relatively high. Bare metal stents (BMS) significantly reduce restenosis compared to balloon angioplasty alone, yet the incidence of restenosis and reocclusion remains very high. In the Total Occlusion Study of Canada (TOSCA) 1 trial, the 6-month incidence of restenosis and reocclusion with BMS exceeded 50% and 10%, respectively.

First-generation drug-eluting stents (DES) significantly reduce restenosis compared with BMS ( Table 11.1 ). The first randomized-controlled trial comparing BMS and DES was the Primary Stenting of Totally Occluded Native Coronary Arteries ( PRISON II) trial that compared BMS with the sirolimus-eluting stent (SES; Cypher, Cordis). The SES significantly reduced the 6-month incidence of binary angiographic restenosis (from 41% to 11%, P < .001), vessel reocclusion (from 13% to 4%, P < .04), and the need for new revascularization procedures (from 22% to 8%, P < .001) compared with BMS. The benefit persisted at 5-year follow-up angiography, although some late catch-up in lumen diameter loss was observed in the SES group. Two other studies, the Gruppo Italiano di Studio sullo Stent nelle Occlusioni Coronariche Societá Italiana di Cardiologia Invasiva ( GISSOC II-GISE ) and the CORACTO trial showed similar results. Four metaanalyses on DES versus BMS in CTOs were published in 2010–2011, all reporting significant reduction in the risk for restenosis, reocclusion, and repeat revascularization with DES. DES appeared to be safe in CTOs, although the risk for stent thrombosis was higher with DES in one metaanalysis.

Second-generation DES have been shown to provide incremental benefit compared with the first-generation paclitaxel-eluting stent in non-CTO lesions. Three randomized clinical trials have compared the first-generation SES with the second-generation everolimus-eluting stent (EES; Xience V, Abbott Vascular) and zotarolimus-eluting stent (ZES; Medtronic) in CTOs. The Chronic Coronary Occlusion Treated by Everolimus-Eluting Stent ( CIBELES ) compared EES with SES and demonstrated similar restenosis and repeat revascularization rates, with a trend for lower stent thrombosis risk in the EES group (3% vs. 0%, P = .075). The Catholic Total Occlusion study ( CATOS ) trial showed similar angiographic and clinical outcomes with the SES and the Endeavor ZES (Medtronic). In contrast, the PRISON III trial reported higher in-segment late lumen loss at 8-month follow-up angiography with the Endeavor ZES compared with the SES, although rates were similar with the Resolute ZES.

In an Italian registry of 802 patients undergoing CTO percutaneous coronary intervention (PCI) over 8 years, use of EES was associated with a significantly lower reocclusion rate compared with first-generation DES (3.0% vs. 10.1%; P < .001). However, in the Angiographic Evaluation of the Everolimus-Eluting Stent in Chronic Total Occlusion ( ACE-CTO ) study that included very long lesion and stent length and a high proportion of patients with prior coronary artery bypass graft surgery, target lesion revascularization rates were significantly higher (37% at 12 months). In the Evaluation of the XIENCE Coronary Stent, Performance, and Technique in Chronic Total Occlusions ( EXPERT-CTO ) study of 250 patients (with CTO PCI success in 222) from 20 US centers target lesion revascularization at 1 year was 6.3%.

The PRISON IV trial randomized 330 patients to either an ultrathin-strut sirolimus-eluting stent (Orsiro SES, Biotronik) with biodegradable polymer or the durable polymer Xience EES, and failed to show noninferiority for the primary endpoint of in-segment late lumen loss (0.13 ± 0.63 mm for Orsiro SES vs. 0.02 ± 0.47 mm for EES; P = .08 for noninferiority). In-stent and in-segment binary restenosis was significantly higher with Orsiro SES as compared with EES (8.0% vs. 2.1%; P = .028), with trend for higher risk for target-lesion and target-vessel revascularization (9.2% vs. 4.0% [ P = .08] and 9.2% vs. 6.0% [ P = .33]).

Bioabsorbable scaffolds have been used in CTOs, where they held great promise given the frequently long length of stent implantation (full metal jacket) and the ability to restore physiologic vasomotion and allow vessel remodeling. Early studies showed promising results with low incidence of adverse events. The Bioresorbable Scaffolds versus Drug-Eluting Stents in Chronic Total Occlusions (BONITO) international multicenter registry compared 153 subjects who were treated with Absorb, with 384 patients who received a second-generation DES. At a median follow-up of 703 days, there were no differences in target-vessel failure (cardiac death, target-vessel myocardial infarction, ischemia-driven target-lesion revascularization) between bioresorbable scaffold and DES (4.6% vs. 7.7%; P = .21). Excellent lesion preparation, high-pressure postdilation, and use of intravascular imaging are recommended to obtain optimal final results. In particular, intravascular imaging is strongly advised in any bioabsorbable scaffold procedure, and particularly in CTO PCI, due to the difficulty of adequately assessing the diameter of chronically underperfused vessels, as well as the need for stenting of long segments with multiple overlaps. Given concerns for increased rates of very late stent thrombosis with bioabsorbable scaffolds additional adequately powered studies with long-term follow-up and comparison with DES-treated subjects are needed.

In patients with prior coronary bypass graft surgery, treatment of a native coronary artery CTO is preferable to treatment of a saphenous vein graft (SVG) CTO supplying the same territory because of very high (>50%) restenosis rates after SVG CTO PCI. Occasionally, occluded SVGs can be used for retrograde access to the native coronary artery CTO. If native CTO PCI is not possible, PCI of the SVG CTO may be a reasonable treatment option.

In summary, durable polymer second-generation DES (EES and Resolute ZES) provide better outcomes compared to first-generation DES and are currently the preferred options for CTO PCI. Novel technologies are needed to address the limitations of current metallic stents in CTOs (i.e., late acquired malapposition, due to significant enlargement of the CTO target vessel after successful recanalization).