Firesorb bioresorbable scaffold for de novo coronary artery disease: 1-year clinical outcomes

Abstract

Background

The first-generation bioresorbable scaffolds (BRS) have been associated with higher rates of device-related adverse outcomes in comparison to everolimus-eluting stents. We aimed to evaluate the efficacy and safety of the thinner-strut (100/125 μm) poly-L-lactic acid-based sirolimus-eluting Firesorb BRS in patients with de novo coronary lesions.

Methods

Patient-level data derived from 1205 patients in the FUTURE-II RCT (n = 215) and FUTURE-III registry (n = 990) were prospectively collected, pooled, and analyzed. The primary endpoint of 1-year target lesion failure (TLF) was defined as a composite of cardiac death, target vessel myocardial infarction, or ischemia-driven target lesion revascularization. The patient-oriented composite endpoint (POCE) of all-cause death, any myocardial infarction, or any revascularization was also analyzed.

Results

At 1-year follow-up, the cumulative rate of TLF was 1.67%, with an upper 95% confidence interval of 2.57%, significantly lower than the objective performance criterion goal of 6.6% (P < 0.001). The rate of single TLF components was 0.42% for cardiac death, 0.92% for target vessel myocardial infarction, and 0.42% for ischemia-driven target lesion revascularization. The cumulative rate of POCE at 1 year was 3.34%. No patient experienced definite or probable device thrombosis during 1-year follow-up.

Conclusions

This pooled, patient-level analysis indicates that the thinner strut Firesorb BRS exhibits promising 1-year efficacy and safety profiles with regard to TLF. However, our findings are only applicable to non-complex lesions; large-scale randomized clinical trials powered to assess clinical endpoints are necessary to evaluate the strategy of Firesorb BRS compared to drug-eluting stents.

Trial registration

ClinicalTrials.gov Identifier: NCT02890160 and NCT03660202.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12916-025-04254-0.

Background

Despite the simplicity and safety of latest-generation drug-eluting stent (DES) [1], permanent intravascular implants elicit complications such as restenosis, stent thrombosis, neoatherosclerosis, and may partially impair vasomotor function of the target vessels [2, 3]. In this context, fully bioresorbable scaffolds (BRS) eluting anti-restenotic drugs were developed as an alternative approach to provide a short-term arterial support until the elution process is completed. In contrast to the generally encouraging outcomes from early investigational studies and clinical trials [4–7], randomized trials with longer follow-up periods and meta-analyses showed inferior clinical results, especially the device thrombosis (DT) rates, in comparison to metallic DES [8, 9]. Strut thickness (> 150 μm), which tends to be twice that of metallic stents, might be the most compelling explanation, leading to greater strut protrusion and turbulent flow, increased neointimal growth, and unfavorable resorption-related process [10, 11]. Several BRS with thinner struts have demonstrated promising efficacy in infrapopliteal artery disease and animal coronary artery models [12, 13].

Firesorb BRS (MicroPort, Shanghai, China), a thinner-strut (100/125 μm) poly-L-lactic acid (PLLA)-based sirolimus-eluting BRS, is designed to reduce lumen protrusion and improve the physiological indices of local blood flow. A first-in-man study has assessed the preliminary feasibility and safety of the novel device [14]. The later multicenter randomized controlled trial (RCT) demonstrated that its angiographic efficacy regarding in-segment late loss was noninferior to the cobalt-chromium everolimus-eluting stent (CoCr-EES) [15]. Here, we conducted the FUTURE-III (A Trial of Firesorb in Patients With Coronary Artery Disease) study to further evaluate the safety and efficacy with a larger sample size and examine the objective performance criterion (OPC) for target lesion failure (TLF).

Methods

Study design and participants

The FUTURE-III trial is conducted to evaluate the safety and efficacy of the Firesorb BRS in patients with de novo coronary lesions. The study included 215 subjects from the FUTURE-II randomized trial and 990 subjects from the FUTURE-III registry. The FUTURE-II RCT compared the Firesorb BRS and cobalt-chromium everolimus-eluting stents in patients with no more than two de novo lesions. The FUTURE-III registry is a prospective, multicenter, single-arm clinical study. Patients aged 18 to 75 years with chronic coronary syndrome or stabilized acute coronary syndrome were eligible for scanning. Patients were suitable for enrollment if they had: (1) one or two de novo target lesions with TIMI flow ≥ 1 and a visual stenosis of ≥ 70% or ≥ 50% with objective evidence of ischemia; if two target lesions are present, they must be present in different major epicardial vessels; (2) visual diameters of the lesions limited to ≥ 2.5 and ≤ 4.0 mm, lesion length limited to ≤ 25 mm. Patients were excluded if they had (1) life expectancy < 1 year; (2) recent myocardial infarction (MI) (< 1 week); (3) bleeding diathesis or known anticoagulation dysfunction; (4) heart failure with a left ventricular ejection fraction of < 40%; (5) included in another RCT; (6) severe left main artery disease; (7) major vessel ostial lesions; (8) bifurcation lesions with a side-branch reference vessel diameter > 2.0 mm; (9) severe triple vessel lesion and required revascularization; (10) in-stent restenosis lesions. A brief summary of these two trials is provided in Additional file 1: Table 1. The participants using Firesorb BRS were pooled and analyzed at the patient level. The study was approved by the local ethics committee and was conducted in part to meet the China Food and Drug Administration’s (CFDA) prospective OPC study requirements for new stents. All participants provided written informed consent for the procedure and the follow-up protocol.

Study device

The Firesorb BRS is a balloon-expandable highly crystallized PLLA backbone scaffold system abluminally coated with PDLLA mixed with sirolimus (4 μg/mm) using highly accurate and precise point spraying techniques. The total strut thickness of the Firesorb BRS is 100 μm for scaffolds with diameters of 2.5 and 2.75 mm and 125 μm for scaffolds with diameters of 3.0 to 4.0 mm. The device sizes applied in the present study ranged from 2.5 to 4.0 mm in diameter and 13 to 29 mm in length. All the BRS were stored at < 25℃. Based on our in vitro experiments, the backbone is designed to be absorbed within approximately 3 years, with an average molecular weight loss of 93% and a mass loss of 44% at 24 months [15]. Consistent with these findings, the first-in-man study with 3-year imaging outcomes demonstrated appropriate intima healing, extensive strut coverage, and a very low incidence of late scaffold discontinuity [14].

Study procedure

Percutaneous coronary intervention (PCI) was performed under dual antiplatelet therapy (DAPT) with aspirin (100 mg/day) and clopidogrel (75 mg/day) or ticagrelor (90 mg twice a day). For patients that were not pre-treated, 300-mg loading doses of aspirin and clopidogrel or 180-mg ticagrelor were administered before the invasive procedure. Unfractionated heparin (70–100 U/kg, intravenous) was administered before PCI and maintained to keep the activated clotting time at 250 to 350 s during the procedure. Optimal pre-dilation, stent sizing and post-dilation (PSP) techniques were highly recommended [16, 17]. Optimal target lesion pre-dilation was pre-specified to achieve a nominal balloon diameter-to-reference vessel diameter (RVD) ratio of 1:1. The scaffold diameter should match the reference vessel diameter to ensure optimal apposition and minimize complications. Optimal deployment was defined by a BRS nominal diameter to RVD ratio between 0.85 and 1.15 [18]. Optimal post-dilation was pre-specified using a non-compliant balloon at high pressure (≥ 16 atm), with the balloon diameter exceeding the nominal scaffold diameter but not by > 0.50 mm. DAPT was prescribed for a minimum of 12 months, and statins were prescribed to all subjects after PCI unless contraindicated.

Endpoints

All subjects were planned to follow up at 1 month, 6 months, and yearly up to 5 years after stent implantation. The primary outcome was 1-year TLF, which was a composite endpoint containing cardiac death, target vessel myocardial infarction (TV-MI), or ischemia-driven target lesion revascularization (ID-TLR). Secondary endpoints were as described below: device success, lesion success, and clinical success; the patient-oriented composite endpoint (POCE), defined as a composite of all-cause death, any MI, or any revascularization; TLF or POCE and its individual components across the follow-up period; and definite or probable DT. Lesion success was defined as successful treatment of all target lesions using at least one study device with final in-scaffold/stent residual stenosis < 30%. Device success was defined as successful scaffold delivery/deployment at the target lesion and delivery system withdrawal with final in-scaffold residual stenosis < 30%. Clinical success was defined as patients with lesion success and no in-hospital (≤ 7 days) TLF. MI was defined as evidence of myocardial injury with necrosis according to the Fourth Universal Definition of Myocardial Infarction [19]. Cardiac death was defined as any death caused by cardiac factors or either unknown or undeterminable factors. Quantitative coronary angiography (QCA) was performed by two experienced and independent observers at core lab (COREMED Medical Technology Co., Ltd, Beijing, China). For each lesion, measurements were conducted in triplicate and average values were recorded. An independent clinical events committee, which was blinded to patient identity, adjudicated all events.

Statistical analysis

The overall sample size for the FUTURE-III trial was calculated based on the primary endpoint, TLF at 1 year. The performance goal (PG) for the primary endpoint is prespecified as 6.6% according to the 1-year outcomes meta-analysis of the Absorb BRS [20], and an expected target value of 4.4% according to the TARGET II trial was chosen [21]. Assuming a 5% attrition rate of follow-up, a sample size of 1200 subjects was required to provide 89% power to meet the prespecified PG at a 2-sided type 1 error rate of 5%. The primary endpoint of TLF at the patient level was analyzed in the full analysis set (FAS). Safety was assessed in all included subjects. Continuous variables are described as means standard deviations and categorical variables are reported as percentages. Time–to–first event curves were performed using Kaplan–Meier estimates. Average hazard ratios were computed with Cox proportional hazard models. All statistical analyses were performed using R version 4.1.2 (R Foundation for Statistical Computing).

Results

Patient and procedural characteristics

As shown in Table 1, the study pooled patient-level data derived from 1,205 patients. The mean age was 58.00 years, the mean body mass index was 25.39, and 73.5% of patients were men. More than a quarter of the patients had diabetes (26.2%). A total of 14.1% had a history of MI, 12.8% had prior PCI, 38.3% had hyperlipidemia, 33.6% were current smokers, and 78.9% were diagnosed with unstable angina.

Table 1.

Baseline clinical characteristics

	FUTURE-III OPC Study (N = 1205)	FUTURE-II RCT N = 215)	FUTURE-III Registry (N = 990)
Male	886 (73.5)	155 (72.1)	731 (73.8)
Age, yrs	58.00 ± 9.71	56.54 ± 9.63	58.32 ± 9.70
Body mass index, kg/m2	25.39 ± 3.45	25.36 ± 3.37	25.40 ± 3.47
Hypertension	728 (60.4)	118 (54.9)	610 (61.6)
Diabetes mellitus	316 (26.2)	55 (25.6)	261 (26.4)
Hyperlipidemia	462 (38.3)	88 (40.9)	374 (37.8)
Chronic kidney disease	50 (4.1)	7 (3.3)	43 (4.3)
Current smoker	405 (33.6)	83 (38.6)	322 (32.5)
Previous MI	170 (14.1)	33 (15.3)	137 (13.8)
Previous PCI	154 (12.8)	30 (14.0)	124 (12.5)
Previous CABG	3 (0.2)	0 (0)	3 (0.3)
LVEF, %	62.93 ± 6.66	62.67 ± 6.22	63.01 ± 9.10
Clinical presentation
Silent ischemia	77 (6.4)	20 (9.3)	57 (5.8)
Stable angina	177 (14.7)	38 (17.7)	139 (14.0)
Unstable angina	951 (78.9)	157 (73.0)	794 (80.2)
DAPT at discharge	1167 (96.9)	204 (94.5)	963 (97.3)
DAPT at 1-year follow-up	1116 (92.6)	203 (94.4)	913 (92.2)

Values are n (%) or mean ± SD

Abbreviations OPC objective performance criterion, RCT randomized controlled trial, MI myocardial infarction, PCI percutaneous coronary intervention, CABG coronary artery bypass graft, LVEF left ventricle ejection fraction, DAPT dual antiplatelet therapy

Angiographic outcomes

The procedural outcomes are presented in Table 2. A total of 1236 lesions was treated with Firesorb BRS in our study, and nearly a half of the target lesions (53.6%) were located in the left anterior descending artery. According to baseline QCA, the average RVD, lesion length, minimum lumen diameter (MLD), and percent diameter stenosis (DS) were 2.94 mm, 13.83 mm, 0.94 mm, and 68.21%, respectively. Overall, pre-dilation was performed in 99.9% of patients, and post-dilation was performed in 95.3% of patients. The mean implanted device diameter was 3.24 mm with a device length of 22.10 mm. After the procedure, the in-device MLD was increased to 2.64, leading to a residual in-device percent DS of 12.07%. The overall lesion success, device success, and clinical success rates were 100%, 99.9%, and 99.2%, respectively.

Table 2.

Procedural characteristics

	FUTURE-III OPC Study (NL = 1236)	FUTURE-II RCT (NL = 221)	FUTURE-III Registry (NL = 1015)
Target vessel location
Left anterior descending	663 (53.6)	129 (58.4)	534 (52.6)
Left circumflex	245 (19.8)	43 (19.5)	202 (19.9)
Right coronary artery	328 (26.5)	49 (22.2)	279 (27.5)
Number of target lesions treated
1	1174 (97.4)	209 (97.2)	965 (97.5)
2	31 (2.6)	6 (2.8)	25 (2.5)
Pre-dilation	1235 (99.9)	221 (100)	1014 (99.9)
Maximum balloon diameter, mm	2.81 ± 0.50	2.77 ± 0.44	2.82 ± 0.51
Balloon diameter/RVD ratio	0.97 ± 0.16	0.97 ± 0.14	0.97 ± 0.16
Maximum pressure, atm	12.65 ± 2.87	12.46 ± 3.13	12.69 ± 2.81
Optimal pre-dilation	509 (41.2)	95 (43.0)	414 (40.8)
Study device implantation
Total device length, mm	22.10 ± 5.26	21.13 ± 5.03	22.31 ± 5.29
Device diameter, mm	3.24 ± 0.47	3.19 ± 0.46	3.25 ± 0.47
Device diameter/RVD	1.11 ± 0.11	1.11 ± 0.11	1.11 ± 0.10
Maximum pressure, atm	11.39 ± 2.22	11.86 ± 2.43	11.28 ± 2.15
Optimal deployment	836 (67.6)	150 (68.9)	686 (67.6)
Post-dilation	1178 (95.3)	211 (95.5)	967 (95.3)
Balloon diameter, mm	3.36 ± 0.48	3.36 ± 0.49	3.36 ± 0.48
Balloon diameter/RVD ratio	1.15 ± 0.11	1.17 ± 0.12	1.15 ± 0.11
Balloon diameter/RVD ratio ≥ 1.1:1	792 (64.1)	153 (69.2)	639 (63.0)
Maximum pressure, atm	16.76 ± 3.03	17.09 ± 2.88	16.67 ± 3.07
≥ 16 atm	839 (67.9)	173 (78.3)	666 (65.6)
Optimal post-dilation	773 (62.5)	162 (73.3)	611 (60.2)
Bailout stenting during procedure	14 (1.1)	3 (1.4)	11 (1.1)
Intracoronary imaging use	189 (15.3)	39 (17.6)	150 (14.8)
Pre-procedure QCA
RVD, mm	2.94 ± 0.49	2.90 ± 0.47	2.95 ± 0.49
Lesion length, mm	13.83 ± 5.24	15.20 ± 6.08	13.53 ± 4.99
MLD, mm	0.94 ± 0.39	0.89 ± 0.37	0.95 ± 0.39
DS, %	68.21 ± 11.75	69.44 ± 11.07	67.94 ± 11.88
Post-procedure QCA
MLD (in-device)	2.64 ± 0.45	2.59 ± 0.44	2.65 ± 0.45
MLD (in-segment)	2.52 ± 0.45	2.48 ± 0.43	2.53 ± 0.45
DS, % (in-device)	12.07 ± 6.55	12.08 ± 6.42	12.08 ± 6.60
DS, % (in-segment)	13.81 ± 6.84	14.15 ± 6.75	13.75 ± 6.86
Lesion success	1236 (100)	221 (100)	1015 (100)
Device success	1235 (99.9)	222 (99.6)	1013 (99.8)
Clinical success, patient level	1195 (99.2)	213 (99.1)	982 (99.2)

Values are n (%) or mean ± SD

Abbreviations N_L number of lesions, QCA quantitative coronary angiography, RVD reference vessel diameter, MLD minimal lumen diameter, DS diameter stenosis, other abbreviations as in Table 1

Clinical outcomes

The FAS population contains 1204 patients, 1 patient was excluded due to protocol violation for having enrolled in another RCT, and 1-year follow-up was completed in 1196 patients (99.3%). As shown in Fig. 1 and Table 3, the cumulative incidence of TLF at 1 year was 1.67%, with a 95% upper CI of 2.57%, significantly lower than the preset PG of 6.6% (P < 0.001) and the chosen expected rate (4.4%). Hence, the prespecified OPC goal for CFDA was achieved. The rate of single TLF components was 0.42% for cardiac death, 0.92% for TV-MI, and 0.42% for ID-TLR. The cumulative rate of POCE in 1204 patients was 3.34%, with all-cause death in 0.42%, any MI in 1.00%, and any revascularization in 2.01% of patients (Fig. 2). Periprocedural MI occurred in 0.75% of the FAS patients. There was no patient who experienced definite or probable DT within 12 months.

Fig. 1.

The cumulative incidence of TLF at 1-year follow-up. TLF, target lesion failure

Table 3.

Clinical outcomes during 1-year follow-up

	1 month	6 months	12 months
Target lesion failure	12 (1.00)	15 (1.25)	20 (1.67)
Patient-oriented composite endpoint	12 (1.00)	19 (1.58)	40 (3.34)
All-cause death	1 (0.08)	3 (0.25)	5 (0.42)
Cardiac death	1 (0.08)	3 (0.25)	5 (0.42)
Any MI	10 (0.83)	11 (0.92)	12 (1.00)
Target-vessel MI	10 (0.83)	11 (0.92)	11 (0.92)
Periprocedural MI	9 (0.75)	9 (0.75)	9 (0.75)
Spontaneous MI	1 (0.08)	2 (0.17)	3 (0.25)
Any revascularization	1 (0.08)	6 (0.50)	24 (2.01)
Ischemia-driven TVR	1 (0.08)	3 (0.25)	8 (0.67)
Ischemia-driven TLR	1 (0.08)	2 (0.17)	5 (0.42)
Definite/probable device thrombosis	0	0	0

Values are n (%). Results are estimated with the Kaplan–Meier method, so values may not calculate mathematically

Target lesion failure was defined as a composite endpoint containing cardiac death, target vessel MI, or ischemia-driven TLR; patient-oriented composite endpoint was a composite of all-cause death, any MI, or any revascularization

Abbreviations MI myocardial infarction, TLR target lesion revascularization, TVR target vessel revascularization

Fig. 2.

The cumulative incidence of A POCE, B death, C myocardial infarction, and D revascularization at 1-year follow-up. POCE, patient-oriented composite endpoint

Sub-analysis

In the terms of the primary endpoint, TLF, no differences were observed across pre-specified subgroups of interest according to age, gender, smoking status, and presence or absence of cardiovascular comorbidities (Fig. 3).

Fig. 3.

Subgroup analyses for the primary endpoint of 1-year TLF. TLF, target lesion failure; HR, hazard ratio; PCI, percutaneous coronary intervention; MI, myocardial infarction

Discussion

The study pooled 1205 patients from the FUTURE-II RCT and FUTURE-III registry, evaluating the clinical outcomes of the Firesorb BRS in treating patients with native coronary lesions. Our main findings indicated that in patients who received the Firesorb BRS, the cumulative incidence of TLF at 1 year was 1.67%, significantly lower than the objective performance criterion goal of 6.6%. Meanwhile, the secondary endpoints, including POCE, the single components of POCE, and DT, were generally low, with high rates of procedural and clinical success. Overall, the thinner strut Firesorb BRS demonstrated favorable safety and efficacy in treating non-complex coronary lesions and achieved the preset OPC goal for TLF.

Metallic stents currently pose an enduring risk of TLF [22, 23], and BRS was thus developed to improve long-term outcomes with contemporary metallic DES. Several large RCTs have demonstrated that BRS was non-inferior to DES in terms of TLF rates at 1 year [6, 24]. However, evidence from a meta-analysis of RCT revealed a higher events rate of the bioresorbable scaffold compared to the metallic stent, driven by events that occurred within the first 3 years. The differences in TLF between BRS and CoCr-EES were similar during the 3- to 5-year follow-up period, when the poly-L-lactic acid had been fully absorbed [8]. In the FUTURE-II RCT, we performed a head-to-head comparison between Firesorb BRS and CoCr-EES, demonstrating non-inferior angiographic in-segment late loss and comparable clinical outcomes at 1 year, although not powered for hard endpoints [15]. In the present multicenter single-armed study, the 1-year TLF rate was 1.9%, with a markedly lower 95% upper CI of 2.9% compared to the OPC prespecified estimate of 6.6%, also appearing lower than those of other BRS, indicating the potential improved efficacy of the novel Firesorb BRS. Similar to our results, the Neovas BRS (Lepu Medical, Beijing, China) showed relatively low rates of both TLF and POCE [25]. While definitive conclusions are precluded due to potential discrepancies in enrolled populations and procedures, the notably low rates of TLF and POCE presented in this pooled analysis strongly bolster the efficacy profile of the Firesorb BRS.

Permanent vascular implant impairs arterial physiology, and the occurrence of very late DT remains a major concern [26], while the occurrence of very late DT is decreased in the second-generation DES compared to that of the first-generation DES [27]. This adverse complication primarily stems from the presence of permanent metallic implants, the chronic degeneration provoked by an inflammatory reaction to the coating polymer, and/or the negative impacts of antiproliferative drugs on endothelial regeneration [10, 26]. Unlike the newer generation DES, BRS tend to exhibit a higher rate of DT within and beyond the first year of implantation. The final report of the ABSORB series studies, which pooled individual patient data from five RCTs involving 5988 patients, revealed higher DT rates through the 3-year follow-up period but showed comparable results between 3 and 5 years [9]. However, consistent with the results from FUTURE-I and FUTURE-II studies [14, 15], we reported that no patients developed DT during the 1-year follow-up, further confirming the safety profile of the Firesorb BRS.

Currently, most BRSs are designed with thicker and wider struts compared to the newer generation DES, resulting in increased strut protrusion, turbulence flow, and platelet activation. The Firesorb BRS is manufactured with thinner struts (100 to 125 μm). In the FUTURE-II trial [15], this device exhibited nearly identical angiographic in-segment late loss and tissue strut coverage as the CoCr-EES, with good expansion properties and low recoil forces as assessed by optical coherence tomography. Furthermore, the new everolimus-coated resorbable scaffold (Esprit-BTK, Abbott Vascular), with a 99- to 120-μm strut thickness, has shown superiority to angioplasty in patients with chronic limb-threatening ischemia due to infrapopliteal artery disease [13]. A novel bioresorbable nitrided iron scaffold with 70-mm strut thickness has shown comparable 1-year efficacy and safety as CoCr-EES in porcine coronary arteries [12]. Therefore, BRS developed with thinner struts may better improve fluid dynamics and facilitate accelerated and comprehensive endothelization. In addition, the following factors may also underlie this finding: (1) Strict entry criteria excluded high-risk patients with complex lesions, which could have potentially increased adverse events. (2) Adherence to the PSP principles. Specifically, precise vessel sizing was performed to avoid stenting very small vessels, and pre-dilation was conducted in 99.9% of all lesions. Post-dilation was performed in 95.3% of all lesions, with a mean pressure of 16.8 atm. This protocol resulted in optimal sizing in 67.6% of cases and achieved optimal post-dilation in 62.5% of lesions, demonstrating superior procedural outcomes compared to the Absorb BRS trials, which reported 50.2% optimal sizing and 12.7% optimal expansion rates [16, 17]. (3) High rate of DAPT prescription following BRS implantation. At the 1-year follow-up, 92.6% of patients remained on DAPT. Findings from the ABSORB and AIDA trials indicated a significantly lower risk of device thrombosis in patients maintained on DAPT compared to those off DAPT [28, 29], we enforced more rigorous DAPT management for enrolled patients and recommended extending DAPT to 3 years to mitigate the risk of device thrombosis.

Study limitations

Several limitations of our study should be noted. First, the FUTURE-III study had the usual limitations of a single-arm investigation with historical controls. RCTs represent the gold standard of scientific rigor utilized by FDA for assessing new devices and therapeutics, yet their utility in addressing individual clinical queries is often hindered by limited statistical power due to small sample sizes and economic and ethical issues of implementation [30–32]. Hence, we used the OPC method to premarket evaluate the thinner strut Firesorb BRS. The unified outcome definitions, strict data management, and high follow-up rates may help mitigate bias and reconfirm the validity of this pooled analysis and the credibility of the conclusions. Second, enrollment in our study was confined to patients with relatively stable symptoms and uncomplicated coronary lesions. Although our findings met the prespecified PG, the observed event rates were lower than initially anticipated. This lower-than-expected event rate should be considered when interpreting the study results, as it might limit the generalizability to all-comer populations. However, in the INFINITY-SWEDEHEART trial, the TLF rate of contemporary DES at 1 year in the general population (including different types of acute coronary syndrome, complex lesions, long lesions, and small vessels) was 2.8% [33]. These improvements can be attributed to the evolution and refinement of interventional devices as well as the optimization of medical treatment strategies. Third, the use of intravascular imaging techniques such as optical coherence tomography and intravascular ultrasound may enhance the optimization of vessel preparation, stent sizing, and post-dilatation processes for BRS. A recent Japanese study with a relatively small sample size, which used intracoronary imaging-guided BRS implantation, reported zero cases of ABSORB GT1 scaffold thrombosis over a 5-year follow-up [34]. In our FUTURE III study, intravascular imaging was used in 15.3% of cases, yet the TLF rate was not significantly lower in this subgroup. It should be noted that the study protocol did not prespecify the use and data collection of intravascular imaging. Another RCT demonstrated no significant reduction in nonoptimal BRS deployment with OCT versus angiography guidance, with no long-term clinical data reported [35]. Finally, although the clinical outcomes were promising, the current study only had 1 year of follow-up, which is insufficient to determine whether there are meaningful late clinical outcomes. Further follow-up investigation concerning the clinical endpoints is ongoing.

Conclusions

In conclusion, this pooled, patient-level analysis indicates that the thinner strut Firesorb BRS achieves the OPC goal with regard to TLF at 1 year and exhibits promising efficacy and safety profiles in patients with de novo non-complex lesions.

Abbreviations

BRS

Bioresorbable scaffolds

DAPT

Dual antiplatelet therapy

DES

Drug-eluting stent

DS

Percent diameter stenosis

DT

Device thrombosis

MI

Myocardial infarction

MLD

Minimum lumen diameter

PCI

Percutaneous coronary intervention

PSP

Pre-dilation, stent sizing and post-dilation

POCE

Patient-oriented composite endpoint

QCA

Quantitative coronary angiography

RCT

Randomized controlled trial

RVD

Reference vessel diameter

TLF

Target lesion failure

Authors’ contributions

J.W., R.G. and J.J. designed the study and drafted the article. C.L., D.C., L.S., Z.C., P.L., L.G., Y.C., H.L., S.J., S.H., W.L. conducted subject enrollment and data acquisition, D.C. and J.J. performed data analysis and interpretation. J.W., R.G. and J.J. revised the manuscript. All authors read and approved the final manuscript.

Funding

The study was funded by the National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2023ZD0504100), Transvascular Implantation Devices Research Institute (KY012024002), and the National Natural Science Foundation of China (No. 82170332).

Data availability

The FUTURE III trial is planned to continue follow-up for 5 years. Patient-level data collected for this study will not be made publicly available. Any reasonable inquiries should be sent to the corresponding author.

Declarations

Ethics approval and consent to participate

Our study was conducted in accordance with the Helsinki Declaration and was approved by the ethical review board of all participated centers (approval number: I2019001617 for The Second Affiliated Hospital, Zhejiang University School of Medicine, 2016-772 for Fu Wai Hospital, 2019-020 for Chinese PLA General Hospital, 2019-QX-011 for General Hospital of Ningxia Medical University, TZS-2021-002-01 for The First People’s Hospital of Yulin, XZXY-LQ-20200109-005 for Xuzhou Central Hospital, 2020-002-01 for Inner Mongolia Autonomous Region People’s Hospital, 2020-01-C for Affiliated Hospital of Jining Medical University, 2020-05-02 for Daqing Oilfield General Hospital, and 2020007 for Northern Jiangsu People’s Hospital).

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.