Imaging and 2-year clinical outcomes of thin strut sirolimus-eluting bioresorbable vascular scaffold: The MeRes-1 extend trial.

OBJECTIVES: This study explores the safety and efficacy of thin strut MeRes100 sirolimus-eluting bioresorbable vascular scaffold (BRS) in patients with de novo coronary artery lesions. BACKGROUND: In interventional cardiology, the emergence of BRS technology is catalyzing the next paradigm shift. METHODS: The MeRes-1 Extend was a multicenter, prospective, single-arm, open-label study enrolling 64 patients in Spain, Macedonia, Brazil, South Africa, Malaysia, and Indonesia. The safety endpoint was major adverse cardiac events (MACE) which composed of cardiac death, myocardial infarction (MI), and ischemia-driven target lesion revascularization (ID-TLR). The imaging efficacy endpoint was mean in-scaffold late lumen loss (LLL) evaluated by quantitative coronary angiography (QCA). Optical coherence tomography (OCT) imaging was performed at baseline and 6-month follow-up. RESULTS: A total of 69 target lesions were identified in 64 enrolled patients (mean age 58.30 ± 9.02 years). Of the treated lesions, 49 (71.01%) lesions were of type B2/C. Procedural and device success was achieved in 64 and 62 patients, respectively. At 2-year follow-up, MACE was reported in one patient (1.61%) in the form of ID-TLR. There was no case of MI, cardiac death or scaffold thrombosis through 2-year. In a subset of 32 patients, paired QCA showed mean in-scaffold LLL of 0.18 ± 0.31 mm at 6-month follow-up. In a subset of 21 patients, OCT revealed 97.95 ± 3.69% strut coverage with mean scaffold area of 7.56 ± 1.79 mm2 and no evidence of strut malapposition. CONCLUSIONS: The clinical and imaging outcomes of MeRes-1 Extend trial demonstrated favorable safety and efficacy of MeRes100 sirolimus-eluting BRS in patients with de novo coronary artery lesions.

Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI.

BACKGROUND: Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR. METHODS: We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk. RESULTS: At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001). CONCLUSIONS: Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .).

Mortality prediction after transcatheter treatment of failed bioprosthetic aortic valves utilizing various international scoring systems: Insights from the Valve-in-Valve International Data (VIVID).

BACKGROUND: Transcatheter Aortic Valve Implantation (TAVI) is commonly used to deploy new bioprosthetic valves inside degenerated surgically implanted aortic valves in high risk patients. The three scoring systems used to assess risk of postprocedural mortality are: Logistic EuroSCORE (LES), EuroSCORE II (ES II), and Society of Thoracic Surgeons (STS). OBJECTIVE: The purpose of this study is to analyze the accuracy of LES, ES II, and STS in estimating all-cause mortality after transcatheter aortic valve-in-valve (ViV) implantations, which was not assessed before. METHODS: Using the Valve-in-Valve International Data (VIVID) registry, a total of 1,550 patients from 110 centers were included. The study compared the observed 30-day overall mortality vs. the respective predicted mortalities calculated by risk scores. The accuracy of prediction models was assessed based on calibration and discrimination. RESULTS: Observed mortality at 30 days was 5.3%, while average expected mortalities by LES, ES II and STS were 29.49 (± 17.2), 14.59 (± 8.6), and 9.61 (± 8.51), respectively. All three risk scores overestimated 30-day mortality with ratios of 0.176 (95% CI 0.138-0.214), 0.342 (95% CI 0.264-0.419), and 0.536 (95% CI 0.421-0.651), respectively. 30-day mortality ROC curves demonstrated that ES II had the largest AUC at 0.722, followed by STS at 0.704, and LES at 0.698. CONCLUSIONS: All three scores overestimated mortality at 30 days with ES II showing the highest predictability compared to LES and STS; and therefore, should be recommended for ViV procedures. There is a need for a dedicated scoring system for patients undergoing ViV interventions.

Real-time use of instantaneous wave-free ratio: results of the ADVISE in-practice: an international, multicenter evaluation of instantaneous wave-free ratio in clinical practice.

OBJECTIVES: To evaluate the first experience of real-time instantaneous wave-free ratio (iFR) measurement by clinicians. BACKGROUND: The iFR is a new vasodilator-free index of coronary stenosis severity, calculated as a trans-lesion pressure ratio during a specific period of baseline diastole, when distal resistance is lowest and stable. Because all previous studies have calculated iFR offline, the feasibility of real-time iFR measurement has never been assessed. METHODS: Three hundred ninety-two stenoses with angiographically intermediate stenoses were included in this multicenter international analysis. Instantaneous wave-free ratio and fractional flow reserve (FFR) were performed in real time on commercially available consoles. The classification agreement of coronary stenoses between iFR and FFR was calculated. RESULTS: Instantaneous wave-free ratio and FFR maintain a close level of diagnostic agreement when both are measured by clinicians in real time (for a clinical 0.80 FFR cutoff: area under the receiver operating characteristic curve [ROC(AUC)] 0.87, classification match 80%, and optimal iFR cutoff 0.90; for a ischemic 0.75 FFR cutoff: iFR ROC(AUC) 0.90, classification match 88%, and optimal iFR cutoff 0.85; if the FFR 0.75-0.80 gray zone is accounted for: ROC(AUC) 0.93, classification match 92%). When iFR and FFR are evaluated together in a hybrid decision-making strategy, 61% of the population is spared from vasodilator while maintaining a 94% overall agreement with FFR lesion classification. CONCLUSION: When measured in real time, iFR maintains the close relationship to FFR reported in offline studies. These findings confirm the feasibility and reliability of real-time iFR calculation by clinicians.

Hybrid rotablation and drug-eluting balloon strategy.

AIM: The aim was to assess the safety and efficacy of rotational atherectomy followed by drug-eluting balloon (DEB) in patients with a high risk of bleeding. METHODS: A retrospective review was carried out of hospital records of consecutive patients who underwent the hybrid procedure. RESULTS: The average age of the 23 patients was 74 years. Risk factors for bleeding included renal failure (35%), oral anticoagulation use (26%) and peptic ulcer disease (35%). All patients had procedural success. No bleeding was reported over the 24-month follow-up period. Dual antiplatelet therapy was stopped successfully in six patients (26%) at three months. Two patients had confirmed target-lesion failure (restenosis). Two patients died over the study period but the cause of death was not known to be cardiovascular disease related. CONCLUSIONS: For patients at high risk of bleeding who require rotablation, the use of a drug-eluting balloon may be a safe, effective alternative.

Sealing of Coronary Perforations With a Second-Generation Covered Stent Graft - Results From the PAST-PERF Registry.

BACKGROUND: The PAST-PERF registry was initiated to collect data on the PK Papyrus covered stent, a second-generation device for the treatment of coronary artery perforations with enhanced mechanical properties, but with limited available data. METHODS: Patients treated for coronary artery perforations with the PK Papyrus stent at 14 international centers were retrospectively identified. The primary effectiveness outcome was successful sealing of the perforation. The primary safety outcome was a composite of all-cause mortality, definite or probable stent thrombosis, myocardial infarction and target lesion revascularization. RESULTS: Among the 94 included patients, 72.3% (68/94) had Ellis type III and cavity spilling perforations. Complete sealing was achieved in 93.6% (n = 88), and no sealing could be achieved in 3.2% (n = 3, including one patient with a geographical miss and one patient in whom the device could not be implanted). Pericardiocentesis was required in 25.0% (n = 23), emergency cardiac surgery was needed in 7.6% (n = 7), acute stent thrombosis was observed in 1.1% (n = 1), and in-hospital mortality occurred in 11.7% (n = 11). The median follow-up duration was 283 (IQR:40;670) days. At 6 and 12 months, the incidence of the primary safety endpoint was 26.6% [95%CI:18.6;37.1] and 32.0% [95%CI:22.8;43.4], mortality 15.0% [95%CI:9.0;24.6] and 19.0% [95%CI:11.3;30.0], and target lesion revascularization 5.5% [95%CI:2.0;14.6] and 7.7% [95%CI:3.1;18.2]. Two definite stent thrombosis occurred, one during the procedure and one on post-procedure day 233. CONCLUSIONS: The registry demonstrates favorably high rates of successful stent delivery and sealing of coronary perforations using a second-generation covered stent with low target lesion revascularization and stent thrombosis rates. ANNOTATED TABLE OF CONTENT: The PAST-PERF registry demonstrates favorably high rates of successful stent delivery and sealing of coronary perforations using a second-generation covered stent with low target lesion revascularization and stent thrombosis rates. Specifically, complete sealing was achieved in 93.6% of patients (n = 88/94), and no sealing could be achieved in 3.2% (n = 3, including one patient with a geographical miss and one patient in whom the device could not be implanted). The 12-month mortality was 19.0% [95%CI:11.3;30.0], the rate of target lesion revascularization was 7.7% [95%CI:3.1;18.2], and two definite stent thromboses occurred (one during procedure and one on post-procedure day 233).

STELLIUM 1: First-in-man follow-up evaluation of bioabsorbable polymer-coated paclitaxel-eluting stent.

BACKGROUND: Durable polymers used for first-generation drug-eluting stents (DES) potentially contribute to persistent inflammation and late DES thrombosis. The vascular response to the Stellium stent, which is coated with an absorbable polymer for slow release of low-dose paclitaxel, was evaluated in the present study. METHODS AND RESULTS: The 37 patients with stable angina were implanted with 47 Stellium stents. Quantitative coronary angiography (QCA) was performed at baseline, and QCA and optical coherence tomography (OCT) were performed at 6 months post-implant. The primary endpoint was major adverse cardiac events (MACE). At 6 months, 1 case of MACE occurred because of total occlusion of a protected left main artery. In-stent and segment binary restenosis rates were both 0%. In-stent late loss was 0.19 ± 0.54 mm. Altogether, 5,564 struts were visualized by OCT and mean neointimal thickness was 150.03 ± 146.36 µm. The number of well-apposed struts with and without neointima overlay was 5,135 (92.29%) and 396 (7.12%), respectively. Peri-strut low intensity was observed in 518 struts (9.31%). CONCLUSIONS: This first-in-man study of the Stellium stent shows the promising possibility of bioabsorbable polymeric surface coating paclitaxel-eluting stents out to 6 months. The low rate of peri-strut low intensity suggests low cellular toxicity of the Stellium stent compared with the first-generation DES.

Outcomes Following Transcatheter Aortic Valve Replacement for Degenerative Stentless Versus Stented Bioprostheses.

OBJECTIVES: A large comprehensive analysis of transcatheter aortic valve replacement (TAVR) was performed for failed stentless bioprostheses. BACKGROUND: Valve-in-valve (ViV) transcatheter aortic replacement (TAVR) is an alternative to redo surgery for patients with a failing aortic bioprosthesis. METHODS: Unadjusted outcome data were collected from the VIVID (Valve-in-Valve International Data) registry between 2007 and 2016 from a total of 1,598 aortic ViV procedures (291 stentless, 1,307 stented bioprostheses). RESULTS: Bioprosthetic failure was secondary to aortic regurgitation in 56% of stentless and 20% stented devices (p < 0.001). ViV-TAVR access was transfemoral in 71.1% stentless and 74.2% stented ViV-TAVR. Self-expanding devices were more frequently used in stentless ViV-TAVR (56.0% vs. 39.9%; p = 0.05), but there was no difference between balloon-expanding and self-expanding TAVR devices for stented ViV-TAVR (48.6% vs. 45.1%). The degree of oversizing for all mechanisms of bioprosthesis failure was 9 ± 10% for stentless ViV-TAVR vs. 6 ± 9% for stented ViV-TAVR (and 8 ± 10% for stentless ViV-TAVR vs. 3 ± 9% for stented ViV-TAVR in patients with predominant aortic regurgitation; both p < 0.001). Initial device malposition (10.3% vs. 6.2%; p = 0.014), second transcatheter device (7.9% vs. 3.4%), coronary obstruction (6.0% vs. 1.5%), and paravalvular leak occurred more frequently in stentless ViV-TAVR (all p < 0.001). Hospital stay duration (median 7 days) was no different, and 30-day (6.6% vs. 4.4%; p = 0.12) and 1-year mortality year (15.8% vs. 12.6%; p = 0.15) were numerically higher, but not statistically different, after stentless ViV-TAVR. CONCLUSIONS: Stentless ViV-TAVR is associated with greater periprocedural complications (initial device malposition, second transcatheter device, coronary obstruction, paravalvular leak), but no difference in 30-day and 1-year outcome.

Comparison of Major Adverse Cardiac Events Between Instantaneous Wave-Free Ratio and Fractional Flow Reserve-Guided Strategy in Patients With or Without Type 2 Diabetes: A Secondary Analysis of a Randomized Clinical Trial.

Importance: Invasive physiologic indices such as fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) are used in clinical practice. Nevertheless, comparative prognostic outcomes of iFR-guided and FFR-guided treatment in patients with type 2 diabetes have not yet been fully investigated. Objective: To compare 1-year clinical outcomes of iFR-guided or FFR-guided treatment in patients with and without diabetes in the Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularization (DEFINE-FLAIR) trial. Design, Setting, and Participants: The DEFINE-FLAIR trial is a multicenter, international, randomized, double-blinded trial that randomly assigned 2492 patients in a 1:1 ratio to undergo either iFR-guided or FFR-guided coronary revascularization. Patients were eligible for trial inclusion if they had intermediate coronary artery disease (40%-70% diameter stenosis) in at least 1 native coronary artery. Data were analyzed between January 2014 and December 2015. Interventions: According to the study protocol, iFR of 0.89 or less and FFR of 0.80 or less were used as criteria for revascularization. When iFR or FFR was higher than the prespecified threshold, revascularization was deferred. Main Outcomes and Measures: The primary end point was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. The incidence of MACE was compared according to the presence of diabetes in iFR-guided and FFR-guided groups. Results: Among the total trial population (2492 patients), 758 patients (30.4%) had diabetes. Mean age of the patients was 66 years, 76% were men (1868 of 2465), and 80% of patients presented with stable angina (1983 of 2465). In the nondiabetes population (68.5%; 1707 patients), iFR guidance was associated with a significantly higher rate of deferral of revascularization than the FFR-guided group (56.5% [n = 477 of 844] vs 46.6% [n = 402 of 863]; P < .001). However, it was not different between the 2 groups in the diabetes population (42.1% [n = 161 of 382] vs 47.1% [n = 177 of 376]; P = .15). At 1 year, the diabetes population showed a significantly higher rate of MACE than the nondiabetes population (8.6% vs 5.6%; adjusted hazard ratio [HR], 1.88; 95% CI, 1.28-2.64; P < .001). However, there was no significant difference in MACE rates between iFR-guided and FFR-guided groups in both the diabetes (10.0% vs 7.2%; adjusted HR, 1.33; 95% CI, 0.78-2.25; P = .30) and nondiabetes population (4.7% vs 6.4%; HR, 0.83; 95% CI, 0.51-1.35; P = .45) (interaction P = .25). Conclusions and Relevance: The diabetes population showed significantly higher risk of MACE than the nondiabetes population, even with the iFR-guided or FFR-guided treatment. The iFR-guided and FFR-guided treatment showed comparable risk of MACE and provided equal safety in selecting revascularization target among patients with diabetes. Trial Registration: ClinicalTrials.gov identifier: NCT02053038.

Sex Differences in Instantaneous Wave-Free Ratio or Fractional Flow Reserve-Guided Revascularization Strategy.

OBJECTIVES: This study sought to evaluate sex differences in procedural characteristics and clinical outcomes of instantaneous wave-free ratio (iFR)- and fractional flow reserve (FFR)-guided revascularization strategies. BACKGROUND: An iFR-guided strategy has shown a lower revascularization rate than an FFR-guided strategy, without differences in clinical outcomes. METHODS: This is a post hoc analysis of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate stenosis to guide Revascularization) study, in which 601 women and 1,891 men were randomized to iFR- or FFR-guided strategy. The primary endpoint was 1-year major adverse cardiac events (MACE), a composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization. RESULTS: Among the entire population, women had a lower number of functionally significant lesions per patient (0.31 ± 0.51 vs. 0.43 ± 0.59; p < 0.001) and less frequently underwent revascularization than men (42.1% vs. 53.1%; p < 0.001). There was no difference in mean iFR value according to sex (0.91 ± 0.09 vs. 0.91 ± 0.10; p = 0.442). However, the mean FFR value was lower in men than in women (0.83 ± 0.09 vs. 0.85 ± 0.10; p = 0.001). In men, an FFR-guided strategy was associated with a higher rate of revascularization than an iFR-guided strategy (57.1% vs. 49.3%; p = 0.001), but this difference was not observed in women (41.4% vs. 42.6%; p = 0.757). There was no difference in MACE rates between iFR- and FFR-guided strategies in both women (5.4% vs. 5.6%, adjusted hazard ratio: 1.10; 95% confidence interval: 0.50 to 2.43; p = 0.805) and men (6.6% vs. 7.0%, adjusted hazard ratio: 0.98; 95% confidence interval: 0.66 to 1.46; p = 0.919). CONCLUSIONS: An FFR-guided strategy was associated with a higher rate of revascularization than iFR-guided strategy in men, but not in women. However, iFR- and FFR-guided strategies showed comparable clinical outcomes, regardless of sex. (Functional Lesion Assessment of Intermediate Stenosis to guide Revascularization [DEFINE-FLAIR]; NCT02053038).

Clinical Events After Deferral of LAD Revascularization Following Physiological Coronary Assessment.

BACKGROUND: Physicians are not always comfortable deferring treatment of a stenosis in the left anterior descending (LAD) artery because of the perception that there is a high risk of major adverse cardiac events (MACE). The authors describe, using the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) trial, MACE rates when LAD lesions are deferred, guided by physiological assessment using fractional flow reserve (FFR) or the instantaneous wave-free ratio (iFR). OBJECTIVES: The purpose of this study was to establish the safety of deferring treatment in the LAD using FFR or iFR within the DEFINE-FLAIR trial. METHODS: MACE rates at 1 year were compared between groups (iFR and FFR) in patients whose physiological assessment led to LAD lesions being deferred. MACE was defined as a composite of cardiovascular death, myocardial infarction (MI), and unplanned revascularization at 1 year. Patients, and staff performing follow-up, were blinded to whether the decision was made with FFR or iFR. Outcomes were adjusted for age and sex. RESULTS: A total of 872 patients had lesions deferred in the LAD (421 guided by FFR, 451 guided by iFR). The event rate with iFR was significantly lower than with FFR (2.44% vs. 5.26%; adjusted HR: 0.46; 95% confidence interval [CI]: 0.22 to 0.95; p = 0.04). This was driven by significantly lower unplanned revascularization with iFR and numerically lower MI (unplanned revascularization: 2.22% iFR vs. 4.99% FFR; adjusted HR: 0.44; 95% CI: 0.21 to 0.93; p = 0.03; MI: 0.44% iFR vs. 2.14% FFR; adjusted HR: 0.23; 95% CI: 0.05 to 1.07; p = 0.06). CONCLUSIONS: iFR-guided deferral appears to be safe for patients with LAD lesions. Patients in whom iFR-guided deferral was performed had statistically significantly lower event rates than those with FFR-guided deferral.

Step-by-step manual for planning and performing bifurcation PCI: a resource-tailored approach.

As bifurcation PCI can often be resource-demanding due to the use of multiple guidewires, balloons and stents, different technical options are sometimes being explored, in different local settings, to meet the need of optimally treating a patient with a bifurcation lesion, while being confronted with limited material resources. Therefore, it seems important to keep a proper balance between what is recognised as the contemporary state of the art, and what is known to be potentially harmful and to be discouraged. Ultimately, the resource-tailored approach to bifurcation PCI may be characterised by the notion of minimum technical requirements for each step of a successful procedure. Hence, this paper describes the logical sequence of steps when performing bifurcation PCI with provisional SB stenting, starting with basic anatomy assessment and ending with the optimisation of MB stenting and the evaluation of the potential need to stent the SB, suggesting, for each step, the minimum technical requirement for a successful intervention.

Pre-Angioplasty Instantaneous Wave-Free Ratio Pullback Predicts Hemodynamic Outcome In Humans With Coronary Artery Disease: Primary Results of the International Multicenter iFR GRADIENT Registry.

OBJECTIVES: The authors sought to evaluate the accuracy of instantaneous wave-Free Ratio (iFR) pullback measurements to predict post-percutaneous coronary intervention (PCI) physiological outcomes, and to quantify how often iFR pullback alters PCI strategy in real-world clinical settings. BACKGROUND: In tandem and diffuse disease, offline analysis of continuous iFR pullback measurement has previously been demonstrated to accurately predict the physiological outcome of revascularization. However, the accuracy of the online analysis approach (iFR pullback) remains untested. METHODS: Angiographically intermediate tandem and/or diffuse lesions were entered into the international, multicenter iFR GRADIENT (Single instantaneous wave-Free Ratio Pullback Pre-Angioplasty Predicts Hemodynamic Outcome Without Wedge Pressure in Human Coronary Artery Disease) registry. Operators were asked to submit their procedural strategy after angiography alone and then after iFR-pullback measurement incorporating virtual PCI and post-PCI iFR prediction. PCI was performed according to standard clinical practice. Following PCI, repeat iFR assessment was performed and the actual versus predicted post-PCI iFR values compared. RESULTS: Mean age was 67 ± 12 years (81% male). Paired pre- and post-PCI iFR were measured in 128 patients (134 vessels). The predicted post-PCI iFR calculated online was 0.93 ± 0.05; observed actual iFR was 0.92 ± 0.06. iFR pullback predicted the post-PCI iFR outcome with 1.4 ± 0.5% error. In comparison to angiography-based decision making, after iFR pullback, decision making was changed in 52 (31%) of vessels; with a reduction in lesion number (-0.18 ± 0.05 lesion/vessel; p = 0.0001) and length (-4.4 ± 1.0 mm/vessel; p < 0.0001). CONCLUSIONS: In tandem and diffuse coronary disease, iFR pullback predicted the physiological outcome of PCI with a high degree of accuracy. Compared with angiography alone, availability of iFR pullback altered revascularization procedural planning in nearly one-third of patients.

Safety of the Deferral of Coronary Revascularization on the Basis of Instantaneous Wave-Free Ratio and Fractional Flow Reserve Measurements in Stable Coronary Artery Disease and Acute Coronary Syndromes.

OBJECTIVES: The aim of this study was to investigate the clinical outcomes of patients deferred from coronary revascularization on the basis of instantaneous wave-free ratio (iFR) or fractional flow reserve (FFR) measurements in stable angina pectoris (SAP) and acute coronary syndromes (ACS). BACKGROUND: Assessment of coronary stenosis severity with pressure guidewires is recommended to determine the need for myocardial revascularization. METHODS: The safety of deferral of coronary revascularization in the pooled per-protocol population (n = 4,486) of the DEFINE-FLAIR (Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularisation) and iFR-SWEDEHEART (Instantaneous Wave-Free Ratio Versus Fractional Flow Reserve in Patients With Stable Angina Pectoris or Acute Coronary Syndrome) randomized clinical trials was investigated. Patients were stratified according to revascularization decision making on the basis of iFR or FFR and to clinical presentation (SAP or ACS). The primary endpoint was major adverse cardiac events (MACE), defined as the composite of all-cause death, nonfatal myocardial infarction, or unplanned revascularization at 1 year. RESULTS: Coronary revascularization was deferred in 2,130 patients. Deferral was performed in 1,117 patients (50%) in the iFR group and 1,013 patients (45%) in the FFR group (p < 0.01). At 1 year, the MACE rate in the deferred population was similar between the iFR and FFR groups (4.12% vs. 4.05%; fully adjusted hazard ratio: 1.13; 95% confidence interval: 0.72 to 1.79; p = 0.60). A clinical presentation with ACS was associated with a higher MACE rate compared with SAP in deferred patients (5.91% vs. 3.64% in ACS and SAP, respectively; fully adjusted hazard ratio: 0.61 in favor of SAP; 95% confidence interval: 0.38 to 0.99; p = 0.04). CONCLUSIONS: Overall, deferral of revascularization is equally safe with both iFR and FFR, with a low MACE rate of about 4%. Lesions were more frequently deferred when iFR was used to assess physiological significance. In deferred patients presenting with ACS, the event rate was significantly increased compared with SAP at 1 year.