Drug-eluting stents (DES) currently represent the default strategy during percutaneous coronary interventions. Notwithstanding the excellent long-term clinical and angiographic results obtained with new-generation DES, even in complex clinical and anatomic scenarios, these devices are not free from failures. This is of concern because the treatment of patients presenting with in-stent restenosis (ISR) remains a challenge. ^, Recent guidelines suggest the use of either new generation DES or drug-eluting balloons (DEB) in these patients (recommendation IA). ¹ Bioresorbable vascular scaffolds (BVS) were introduced to mitigate some of the limitations of DES. As BVS eventually disappear from the vessel wall, they might prevent late device-related failures. However, despite encouraging early results, first-generation polymeric BVS eventually proved to be inferior to new-generation DES regarding both safety and efficacy outcomes and are no longer used. ^, However, other novel BVS are clinically available. In addition, BVS restenosis (BVS-ISR) is still seen in clinical practice. Nevertheless, baseline characteristics, treatment strategies, procedural results, and long-term clinical outcomes of patients treated for BVS-ISR, remain unknown. In these patients, a partial or complete disappearance of the device from the vessel wall may be implicated in the pathogenesis of late restenosis. Indeed, BVS-ISR constitutes a unique novel form of restenosis when the device is partially reabsorbed or, simply, no longer there. Accordingly, treatment of these patients (without an underlying metal layer) with DES or DEB might provide different results to those seen in patients with conventional metallic ISR. This prospective multicenter study sought to assess baseline characteristics, acute procedural results, and long-term clinical outcomes of patients undergoing repeat interventions for BVS-ISR. In addition, we compared the results of the treatment of BVS-ISR with those obtained in patients with bare-metal stents restenosis (BMS-ISR) and DES-ISR. ^,

From January 2016 to December 2018, 117 patients from 23 University Spanish sites were included in the Restenosis Intrastent: Treatment of Bioresorbable Vascular Scaffolds Restenosis (RIBS VII) study (ClinicalTrials.gov Identifier: NCT03167424 ). Inclusion and exclusion criteria were similar to those used in previous randomized RIBS trials. ^, Patients with angina or ischemia presenting with BVS-ISR (>50% diameter stenosis on visual assessment), were eligible. The location of the previously implanted BVS had to be clearly identified at the time of the reintervention and a careful review of the initial BVS implantation procedure was recommended. Patients with long lesions (>32 mm in length) or small vessels (<2.5 mm in diameter) were excluded for consistency with previous RIBS studies. Patients with a BVS implanted within the previous month, those showing angiographic images consistent with thrombus affecting the scaffold, and those with complete occlusions, were not included. Patients with edge BVS-ISR were included when the lesion involved the scaffold edge (recognized by its persistent radiopaque metallic marker or confirmed with intracoronary imaging). Patients with a life expectancy <1 year were excluded. ^{, ,}

RIBS VII is an independent, investigators´ driven initiative devised within the “RIBS program” under the auspices of the Association of Interventional Cardiology of the Spanish Society of Cardiology . The Spanish Society of Cardiology was the promoter of the study and the Hospital Universitario de La Princesa (Madrid), was the coordinating center. An unrestricted research grant was obtained from Abbott Vascular that played no role in the study design, data analysis, or interpretation. The study protocol was approved by the Ethics Committee at the coordinating center and then shared with all participating sites, according to current Spanish legislation. All patients provided written informed consent. The primary study end point was the occurrence of major adverse events (death, myocardial infarction [MI], target vessel revascularization [TVR]) (major adverse cardiac event [MACE]-TVR), at 1 year. Secondary end points included the combination of cardiac death, MI, and target lesion revascularization (TLR) (MACE-TLR) and the corresponding individual clinical events.

The Restenosis Intra-stent of Drug-eluting Stents: Drug-eluting Balloon vs Everolimus-eluting Stent (RIBS IV) study compared DEB versus everolimus-eluting stents (EES) in patients with DES-ISR, ( ClinicalTrials.gov Identifier: NCT01239940 ). RIBS IV allocated 309 patients with DES-ISR to either DEB (n = 154) or EES (n = 155). The Restenosis Intra-stent of Bare-metal Stents: Drug-eluting Balloon vs Everolimus-eluting Stent (RIBS V) randomized trial compared DEB versus EES in patients with BMS-ISR, ( ClinicalTrials.gov Identifier: NCT01239953 ). The study allocated 189 patients with BMS-ISR to either DEB (n = 95) or EES (n = 94). The RIBS VII protocol prespecified the comparison of the study results with those obtained in the RIBS IV and V trials.

The protocol for coronary interventions in RIBS VII was identical to that in previous RIBS studies. ^{, ,} Special care was taken to ensure optimal lesion preparation before definitive treatment. In this regard, major care was taken to visualize and treat the entire lesion length (narrowing) but avoiding damaging the adjacent coronary segments. The use of plain or scoring balloons for lesion preparation was left to the operator´s criteria. When an under-expanded BVS was suspected (i.e., “waist” in the predilation balloon, suboptimal angiographic result) it was aggressively tackled with noncompliant balloons at very high pressures. ^, In the RIBS VII protocol the use of new-generation DES was suggested but the final intervention (DES, DEB, BMS, BVS, scoring, or plain balloons) was left to the criteria of the investigator. Postdilation with noncompliant balloons was recommended after the use of BMS, DES, or BVS. Liberal use of intracoronary imaging was also recommended following clinical practice guidelines.

In all patients, serial assessment of cardiac biomarkers and 12-lead electrocardiograms were systematically obtained. ^{, ,} Dual antiplatelet therapy was recommended for 1 year after DES and BVS implantation.

In RIBS VII, the same electronic case-report forms and database of the previous RIBS trials were used. ^{, ,} Data were centrally audited for plausibility, consistency, and queries were generated and submitted to the sites when required. An independent and blinded Clinical Event Committee adjudicated all adverse events after carefully reviewing the corresponding anonymized source documents. All deaths were considered as cardiac unless a different definitive cause could be documented. The diagnosis of MI was based on the same criteria as previous RIBS trials. ^{, ,} The protocol emphasized that repeated interventions at follow-up had to be clinically indicated. Otherwise, physiological assessment of lesion severity was required before reintervention. All repeated revascularization procedures during follow-up were centrally reviewed to evaluate the precise location of the intervention. Stent thrombosis was classified using the Academic Research Consortium definition.

All coronary angiograms were analyzed by expert personnel in the centralized core lab using a well-established standard methodology identical to that used in the previous RIBS studies. ^, Following intracoronary nitroglycerin administration, angiographic lesion patterns were characterized using both the Mehran and the American College of Cardiology/American Heart Association classifications. A validated edge-detection system was used for quantitative coronary angiography (CAAS II System, Pie Medical, Maastricht, The Netherlands). ^{, ,} All quantitative analyses encompassed in-lesion and in-segment (initial lesion + injured segment + 5-mm margins) measurements. The comparison of acute angiographic results (minimal lumen diameter, % diameter stenosis, acute lumen gain) among the 3 groups was predefined. Although the protocol of RIBS VII did not require systematic late angiographic surveillance, all angiograms obtained during follow-up were analyzed.

Continuous data are presented as mean (SD) or median (interquartile range) as required. The Kolmogorov-Smirnov test was used to assess data distribution normality. Continuous data are compared with the Student’s or the Wilcoxon rank sum tests. Categorical data are compared with Pearson’s chi-square or Fisher’s exact tests. Event-free survival in the different cohorts was estimated using Kaplan-Meier curves and compared using the log-rank and Berslow’s tests. Cox proportional hazards regression analyses were performed to assess outcome measures after adjusting for potential confounders in the different groups (BVS-ISR, DES-ISR, and BMS-ISR). Variables showing statistical differences at univariate analysis ( Tables 1 and 2 ) were entered in the multivariate models after excluding collinearity. Crude and adjusted relative risk and hazard ratios (with 95% confidence interval) were obtained using exacts calculations from STATA. The statistical software SPSS for Windows, version 15.0. (Chicago, SPSS Inc) was used. A p value <0.05 was considered statistically significant.

Baseline clinical and angiographic characteristics of patients treated with BVS-ISR (RIBS VII), DES-ISR (RIBS IV), and BMS-ISR (RIBS V) are listed in Table 1 . Patients with BVS-ISR were younger, had a lower prevalence of hypertension, and had more often >1 stent at the target lesion. Patients with BVS-ISR more frequently had lesions located in the left anterior descending coronary artery and complex lesions. Quantitative angiography data are listed in Table 2 . Before intervention BVS-ISR were located in larger vessels compared to patients with DES-ISR or BMS-ISR. Lesion length was longer in patients with BVS-ISR compared with those with DES-ISR. Procedural data including final pressure and balloon to artery ratio were similar in the 3 groups. After the intervention, patients treated for BVS-ISR showed higher in-segment residual diameter stenosis (19 ± 13%, 15 ± 11%, 15 ± 12%, p <0.001) but obtained similar acute lumen gain and minimal lumen diameter compared with patients treated for DES-ISR and BMS-ISR ( Table 2 ).

Clinical follow-up at 1 year was obtained in 100% of patients in the 3 groups (BVS-ISR, DES-ISR, and BMS-ISR) ( Table 3 ). In the BVS-ISR cohort, 2 patients (1.7%) died at 1 year (1 cardiac death), 1 patient (0.9%) suffered a MI, 7 patients (6%) required TLR, and 9 (7.7%) TVR. All patients with BVS-ISR undergoing revascularization at follow-up had angina or objective evidence of ischemia. The combined clinical outcome measure of MACE-TLR and MACE-TVR occurred in 8 (6.8%) and 10 (8.5%) patients, respectively. The rate of adverse events at 1-year follow-up was similar in the 3 groups ( Figure 1 , Table 3 ). Rates of TVR and TLR were numerically lower in patients with BMS-ISR and numerically higher in those with DES-ISR (both p = NS).

Table 3

Major Adverse Clinical Events (1 year)

Variable	BVS-ISR (n = 117)	DES-ISR (n = 309)	BMS-ISR (n = 189)	BVS-ISR vs DES-ISR		BVS-ISR vs BMS-ISR
				HR (95% CI)	p	HR (95% CI)	p
Death	2 (1.7%)	7 (2.3%)	4 (2.1%)	0.75 (0.16 to 3.60)	0.711	0.80 (0.15 to 4.38)	0.796
Cardiac death	1 (0.9%)	4 (1.3%)	1 (0.5%)	0.66 (0.07 to 5.87)	0.694	1.60 (0.10 to 25.57)	0.741
Myocardial infarction	1 (0.9%)	7 (2.3%)	7 (3.7%)	0.37 (0.05 to 3.04)	0.301	0.23 (0.03 to 1.85)	0.101
TLR	7 (6.0%)	27 (8.7%)	7 (3.7%)	0.67 (0.29 to 1.53)	0.319	1.63 (0.57 to 4.64)	0.365
TVR	9 (7.7%)	38 (12.3%)	8 (4.2%)	0.61 (0.29 to 1.25)	0.154	1.84 (0.71 to 4.77)	0.210
Composite MACE (with TLR)	8 (6.8%)	34 (11%)	13 (6.9%)	0.60 (0.28 to 1.30)	0.172	0.98 (0.41 to 2.36)	0.962
Composite MACE (with TVR)	10 (8.5%)	44 (14.2%)	14 (7.4%)	0.58 (0.29 to 1.15)	0.097	1.14 (0.51 to 2.57)	0.750
Definitive thrombosis	1 (0.9%)	3 (1%)	1 (0.5%)	0.88 (0.09 to 8.46)	0.912	1.62 (0.10 to 25.93)	0.732

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