Author + information
- Received October 4, 2019
- Revision received January 27, 2020
- Accepted January 28, 2020
- Published online May 4, 2020.
- Kefei Dou, MDa,b,c,∗∗ (, )
- Dong Zhang, MDa,b,c,∗,
- Hongwei Pan, MDd,∗,
- Ning Guo, MDe,
- Lang Li, MDf,
- Yue Li, MDg,
- Qi Zhang, MDh,
- Bin Liu, MDi,
- Zhujun Shen, MDj,
- Bin Zhang, MDk,
- Jian Liu, MDl,
- Wei Han, MDm,
- Yang Wang, MScn,
- Yanyan Zhao, MScn,
- Yuejin Yang, MDa,b,c,
- Shaoliang Chen, MDo,
- Lihua Xie, MScp,
- Changdong Guan, MScp,
- Ajay J. Kirtane, MD, SMq,
- Bo Xu, MBBSc,p,∗ (, )
- for the CIT-RESOLVE Investigators
- aState Key Laboratory of Cardiovascular Disease, Beijing, China
- bDepartment of Cardiology, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- cNational Clinical Research Center for Cardiovascular Diseases, Beijing, China
- dDepartment of Cardiology, Hunan Provincial People’s Hospital, the First Affiliated Hospital of Hunan Normal University, Changsha, China
- eDepartment of Cardiology, the First Affiliated Hospital of Xi’an Jiaotong University, Xi’an, China
- fDepartment of Cardiology, the First Affiliated Hospital of Guangxi Medical University, Nanning, China
- gDepartment of Cardiology, the First Affiliated Hospital of Harbin Medical University, Harbin, China
- hDepartment of Cardiology, Shanghai East Hospital, Tongji University, Shanghai, China
- iDepartment of Cardiology, the Second Hospital of Jilin University, Changchun, China
- jDepartment of Cardiology, Peking Union Medical College Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- kDepartment of Cardiology, Guangdong General Hospital, Guangzhou, China
- lDepartments of Cardiology, Peking University People’s Hospital, Beijing, China
- mDepartment of Cardiology, the Third Medical Center of the Chinese People’s Liberation Army General Hospital, Beijing, China
- nMedical Research and Biometrics Center, National Center for Cardiovascular Diseases, Beijing, China
- oDepartment of Cardiology, Nanjing First Hospital, Nanjing Medical University, Nanjing, China
- pCatheterization Laboratories, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
- qCenter for Interventional Vascular Therapy, Columbia University Medical Center/NewYork-Presbyterian Hospital, and the Cardiovascular Research Foundation, New York, New York
- ↵∗Address for correspondence:
Dr. Bo Xu or Dr. Kefei Dou, Catheterization Laboratories or Department of Cardiology, Fu Wai Hospital, National Center for Cardiovascular Diseases, Chinese Academy of Medical Sciences and Peking Union Medical College, National Clinical Research Center for Cardiovascular Diseases, A 167, Beilishi Road, Xicheng District, Beijing 100037, China.
Objectives The aim of this study was to determine whether an active side branch protection (SB-P) strategy is superior to the conventional strategy in reducing side branch (SB) occlusion in high-risk bifurcation treatment.
Background Accurate prediction of SB occlusion after main vessel stenting followed by the use of specific strategies to prevent occlusion would be beneficial during bifurcation intervention.
Methods Eligible patients who had a bifurcation lesions with high risk for occlusion as determined using the validated V-RESOLVE (Visual Estimation for Risk Prediction of Side Branch Occlusion in Coronary Bifurcation Intervention) score were randomized to an active SB-P strategy group (elective 2-stent strategy for large SBs and jailed balloon technique for small SBs) or a conventional strategy group (provisional stenting for large SBs and jailed wire technique for small SBs) in a 1:1 ratio stratified by SB vessel size. The primary endpoint of SB occlusion was defined as an angiography core laboratory–assessed decrease in TIMI (Thrombolysis In Myocardial Infarction) flow grade or absence of flow in the SB immediately after full apposition of the main vessel stent to the vessel wall.
Results A total of 335 subjects at 16 sites were randomized to the SB-P group (n = 168) and conventional group (n = 167). Patients in the SB-P versus conventional strategy group had a significantly lower rate of SB occlusion (7.7% [13 of 168] vs. 18.0% [30 of 167]; risk difference: –9.1%; 95% confidence interval: −13.1% to −1.8%; p = 0.006), driven mainly by the difference in the small SB subgroup (jailed balloon technique vs. jailed wire technique: 8.1% vs. 18.5%; p = 0.01).
Conclusions An active SB-P strategy is superior to a conventional strategy in reducing SB occlusion when treating high-risk bifurcation lesions. (Conventional Versus Intentional Strategy in Patients With High Risk Prediction of Side Branch Occlusion in Coronary Bifurcation Intervention [CIT-RESOLVE]; NCT02644434)
- active side branch protection strategy
- conventional strategy
- coronary bifurcation intervention
- randomized controlled trial
- side branch occlusion
Abrupt closure of a side branch (SB) after main vessel (MV) stenting is a challenging complication during bifurcation lesion intervention and may lead to serious adverse clinical events (1,2). The lack of a useful tool for risk prediction of SB occlusion had precluded validation in randomized trials that a more active SB protection (SB-P) strategy is associated with of a lower rate of SB occlusion in high-risk bifurcation lesions. The V-RESOLVE (Visual Estimation for Risk Prediction of Side Branch Occlusion in Coronary Bifurcation Intervention) score was developed to risk-stratify individual bifurcation lesions and inform the choice of an active SB-P strategy (3,4). Although a V-RESOLVE score ≥12 points was associated with higher risk for SB occlusion (5), no randomized trials had prospectively assessed the utility of the scoring system to inform strategy choice, particularly for high-risk bifurcations.
The aim of the present study was to determine whether an active SB-P strategy is superior to the conventional strategy in reducing SB occlusion during percutaneous coronary intervention (PCI) of bifurcation lesions at risk for SB compromise.
Study design and population
As previously reported (6), CIT-RESOLVE was an investigator-initiated, prospective, multicenter, single-blinded (patients were masked), randomized controlled trial conducted at 16 hospitals in China. Adult patients (18 to 75 years of age) presenting with symptomatic coronary artery disease and objective evidence of ischemia or silent ischemia who were eligible for PCI were recruited at participating centers. Patients were eligible if they had at least 1 coronary bifurcation lesion requiring stent implantation, with estimated MV reference vessel diameter (RVD) of 2.25 to 4.0 mm, SB RVD ≥2.0 mm, and V-RESOLVE score ≥12 points. The V-RESOLVE score was used for risk stratification (3) and was derived from evaluation by investigators at each site of 6 independent risk factors: plaque distribution, MV TIMI (Thrombolysis In Myocardial Infarction) flow grade before stenting, pre-procedural diameter stenosis of bifurcation core, bifurcation angle, diameter ratio between MV and SB, and diameter stenosis of SB before MV stenting (Supplemental Figure S1). Patients with V-RESOLVE scores ≥12 points were identified as high-risk bifurcation patients on the basis of a previous study. The online V-RESOLVE score was calculated using a dedicated application interface available in both iTunes and Google Play stores. Exclusion criteria were left ventricular ejection fraction <35%, left main bifurcation lesion, and acute myocardial infarction (MI) with the culprit vessel located at the left anterior descending coronary artery and bifurcation lesion (left anterior descending coronary artery/diagonal branch RVD ≥2.5 mm) proximal to the occluded left anterior descending coronary artery segment. Details of the inclusion and exclusion criteria are provided in the Supplemental Appendix. Eligible patients were randomly assigned to the active SB-P strategy group (elective 2-stent strategy for patients with SB RVD ≥2.5 mm and jailed balloon technique for patients with 2.0 mm ≤SB RVD <2.5 mm) or the conventional strategy group (provisional stenting with jailed wire for patients with SB RVD ≥2.5 mm and jailed wire technique for patients with 2.0 mm ≤SB RVD <2.5 mm) in a 1:1 ratio in fixed blocks of 4, stratified by visually estimated RVD of the SB and center using a web-based allocation system.
The study complied with the Declaration of Helsinki. Details of the study organization and participating centers and protocol are provided in the Supplemental Appendix. The study protocol was approved by the investigational review board or ethics committee at each site. All patients provided written informed consent. This investigator-initiated study was jointly supported by research grants from the Investigator Sponsored Studies project (Abbott Vascular, Abbott Laboratories, Abbott Park, Illinois; study number COR-10498) and the Peking Union Medical College Youth Fund and Fundamental Research Funds for the Central Universities (grant 3332016130). The investigators are solely responsible for the study design, conduct, data analysis and interpretation, report writing, and the decision to submit the manuscript for publication, without any influence from the financial supporters. The CIT-RESOLVE trial was registered at ClinicalTrial.gov (NCT02644434).
All procedures were performed by experienced interventionalists proved to be skilled in bifurcation PCI and qualified to perform both conventional and active SB-P strategies. The minimum annual volume for each participating operator was 200 PCIs. Coronary angioplasty and treatment therapy were according to standard techniques, and the choice of devices and the use of intravascular imaging, including intravascular ultrasound and optical coherence tomography, were at the physician’s discretion. Aspirin ≥100 mg for at least 6 days or a 300-mg loading dose at least 24 h before the intervention procedure and clopidogrel 75 mg for at least 6 days or a 300-mg loading dose at least 6 h before the intervention procedure were administered to all patients. Periprocedural antiplatelet and antithrombotic medications were administered according to current guidelines. After PCI procedures, patients were prescribed aspirin 100 mg/day indefinitely and clopidogrel 75 mg/day for at least 12 months.
Patients in the conventional strategy group were treated using either the jailed wire technique (2.0 mm ≤SB RVD <2.5 mm) or a provisional 2-stent strategy (SB RVD ≥2.5 mm). Those in the SB-P strategy group were treated using either the jailed balloon technique (2.0 mm ≤SB RVD <2.5 mm) or an elective 2-stent strategy (SB RVD ≥2.5 mm); procedural details are provided in the Supplemental Appendix. The intervention treatment was considered successful if final TIMI flow grade 3 was achieved in both the MV and the SB, with residual stenosis of <20%. In cases of severe dissection (types D, E, and F) or unacceptable residual stenosis, post-dilation and bailout stenting were performed to achieve satisfactory acute results. Nontarget lesions could be treated following standard procedures. Planned staged procedures had to be performed within 3 months.
Quantitative coronary angiographic analysis was performed using dedicated bifurcation software (CAAS, Pie Medical Imaging, Maastricht, the Netherlands) by an independent core laboratory following standard process. Quantitative coronary angiographic results were reported for 4 segments of the bifurcation: the proximal MV, distal MV, bifurcation core, and SB. Images avoiding foreshortening or overlap of the bifurcation lesions were required on pre-procedural nidus angiography, during the procedure immediately before MV stenting, and post-procedure for the quantitative coronary angiographic assessment.
Endpoints and definitions
The primary endpoint, SB occlusion, was defined as any decrease in TIMI flow grade or absence of flow in SB immediately after full apposition of the MV stent to the vessel wall, as evaluated by angiographic core laboratory. For patients in the conventional strategy group, TIMI flow grade was assessed immediately after MV stenting (or after post-dilation if performed). For patients in the SB-P strategy group undergoing the jailed balloon technique, TIMI flow grade was assessed immediately after the proximal optimization technique was performed. For patients in the SB-P strategy group who received the elective 2-stent strategy, TIMI flow grade also was assessed immediately after MV stenting (or after post-dilation if performed). Secondary endpoints included rate of periprocedural MI, as defined by Society for Cardiovascular Angiography and Interventions (7), World Health Organization (WHO) (8), and Academic Research Consortium-2 (ARC-2) (9) criteria and major adverse cardiac events (MACE), a composite of all-cause death, MI, or target vessel revascularization at each follow-up time point. Detailed definitions of the endpoints are provided in the Supplemental Appendix. All adverse clinical events were adjudicated by an independent clinical events committee.
In a retrospective study (3), the incidence of SB occlusion was 16.7% in a high-risk population. In the present study, we hypothesized that the incidence of SB occlusion would be much lower than findings from previous all-comers population, considering that the operators involved were experienced interventionalists who were fully aware of the risks as evaluated using the V-RESOLVE score. The proportion of patients with SB occlusion immediately after full apposition of the MV stent to the vessel wall was assumed to be 10% in the conventional strategy group and 4% in the active SB-P strategy group. With a 2-sided α level of 0.05 and maximum 0% rate of loss to follow-up, randomizing 566 recruited patients would provide 80% power to demonstrate superiority of the active SB-P strategy compared with the conventional strategy. All statistical analyses were performed in both the intention-to-treat (ITT) population and the as-treated set (ATS). Continuous variables are presented as mean ± SD and categorical variables as counts and percentages. Group differences were analyzed using Student’s t-test for normally distributed continuous variables and the chi-square or Fisher exact test for categorical variables. The 95% confidence intervals (CIs) of the differences between 2 treatment arms were calculated by using normal approximation for continuous variables and the Wald asymptotic method for binary variables. For primary endpoint analysis, 95% CIs of the difference between 2 treatment arms were calculated using the Cochran-Mantel-Haenszel chi-square test with adjustment for central effects. In addition, because recruitment was prematurely terminated, corresponding post hoc analyses were conducted for the primary endpoint on the basis of both the ITT population and ATS. Pre-specified subgroup analyses were conducted for age, sex, diabetes, V-RESOLVE score, SB RVD, MV RVD, and MV lesion length; odds ratios were calculated using the logistic regression model. All statistical analyses were performed using SAS version 9.4 (SAS Institute, Cary, North Carolina). A 2-sided p value of 0.05 was considered to indicate statistical significant.
Between December 2016 and April 2019, a total of 1,158 subjects at 16 sites were screened. Patients with V-RESOLVE scores <12 points or in whom V-RESOLVE scores could not be calculated because of severe complications after pre-dilation were excluded. Subjects who withdrew their informed consent were excluded after randomization. Because of slow recruitment, at the recommendation of the independent data and safety monitoring board, patient recruitment was stopped on May 30, 2019. For the ITT set, a total of 335 subjects were randomly assigned to the SB-P group (n = 168) or the conventional group (n = 167). Four subjects in the SB-P group crossed over to the conventional group because of technical issues (wiring into the SB could not be achieved or the jailed balloon could not be adequately positioned). Fourteen subjects in the conventional group crossed over to the SB-P group because operators determined a higher risk for SB occlusion and insisted on an active SB-P strategy. For the ATS, 178 patients underwent the active SB-P strategy and 157 patients underwent the conventional strategy (Figure 1).
Baseline, lesion, and procedural characteristics
The baseline and lesion data are shown in Table 1. All baseline and lesion characteristics were balanced between groups. The mean age of the patients was 60 years, and 21.5% (72 of 335) had histories of MI. Most target lesions were true bifurcation lesions. The baseline SYNTAX (Synergy Between PCI With Taxus and Cardiac Surgery) score was 17.5 ± 7.8. Procedural characteristics are shown in Table 2. The active SB-P strategy was applied in most of the patients (97.6%) who were assigned to the SB-P group, yielding significantly higher rates of elective 2-stent strategy (16.7% vs. 0.6%; p < 0.001) and jailed balloon technique (81.0% vs. 7.8%; p < 0.001) used in the SB-P group than in the conventional group, on the basis of vessel size stratification. Details of the jailed balloon technique are provided in Supplemental Table S1. After PCI, the diameter stenosis of the SB in the conventional strategy group was numerically but not significantly more severe than in SB-P strategy group (35.4 ± 21.5% vs. 39.7 ± 20.6%; p = 0.07). Proximal optimization technique and repeat proximal optimization technique rates were low but similar between the 2 groups (35.0% vs. 31.3% [p = 0.48] and 4.9% vs. 1.8% [p = 0.11], respectively). The results of ATS and quantitative coronary angiography are shown in Supplemental Tables S2 to S4.
By ITT analysis, the primary endpoint of SB occlusion occurred in 13 patients (7.7%) in the active SB-P strategy group and 30 patients (18.0%) in the conventional strategy group (risk difference: −9.1%; 95% CI: −13.1% to −1.8%; p = 0.006; odds ratio: 0.38; 95% CI: 0.19 to 0.76) (Table 3, Central Illustration). The difference was driven mainly by a significantly lower TIMI flow grade decrease rate in the SB-P strategy group (5.4% vs. 13.8%; p = 0.009). On the basis of vessel size stratification at randomization, in patients with small SBs (RVD <2.5 mm), SB occlusion occurred in 11 patients (8.1%) in the SB-P strategy group in whom the jailed balloon technique was applied and 28 patients (18.5%) in the conventional strategy group in whom the jailed wire technique was applied (risk difference: −10.2%; 95% CI: −14.2% to −2.6%; p = 0.01). SB occlusion rates were consistent across the examined pre-specified subgroups; all p values for interaction were >0.05 (Figure 2). Similar results were found in the ATS population (Table 3, Supplemental Figure S2).
Periprocedural MI as defined using the Society for Cardiovascular Angiography and Interventions definition was comparable between the 2 groups (4.8% vs. 6.0%; p = 0.62), while according to the sensitivity analysis, periprocedural MI as defined by the WHO or ARC-2 definition was lower in patients in the SB-P strategy group (WHO definition: 6.0% vs. 13.2% [p = 0.02]; ARC-2 definition: 4.8% vs. 9.6% [p = 0.08]) than in the conventional strategy group, and a similar trend was found in the ATS population (Table 4). An exploratory comparison of MACE at 1 month was performed and showed similar results between the 2 groups (6.0% vs. 6.0% [p = 0.99] by ITT analysis and 5.6% vs. 6.4% [p = 0.77] by ATS analysis) (Supplemental Table S5).
The CIT-RESOLVE study, randomizing patients at high risk for SB compromise, demonstrated that an active SB-P strategy, especially the jailed balloon technique for small SBs, was not only feasible but was also associated with a significantly lower incidence of SB occlusion.
Active and conventional SB-P strategies
The current favored approach to coronary bifurcations is a single-stent strategy with a provisional approach to the SB (10,11). However, because of the variability in SB disease and the desire to preserve the patency of diseased SBs, the optimal interventional strategy selection for complex coronary bifurcation lesions remains somewhat controversial. Keeping the SB open is the major goal during bifurcation PCI. SB-P strategies (either through an up-front decision to implant 2 stents or through a jailed balloon technique) are more aggressive in SB-P than the conventional provisional-based approach. Bifurcation lesions at high risk for SB occlusion may require an intentional interventional strategy. The present study, to the best of our knowledge, is the first to show that active SB-P strategy could lower the rate of SB occlusion. Because about 85% patients enrolled in the present study had SB RVDs <2.5 mm, the jailed balloon technique was assigned and applied in the majority of patients in the SB-P strategy group. Although the jailed balloon technique has been associated with a very low rate of SB occlusion (12), and even recommended for very high risk left main disease (13), its effect in SB-P has not been validated in randomized studies. In the present study, 136 patients (81.0%) in the active SB-P strategy group underwent the jailed balloon technique, with a significantly lower rate of SB occlusion than in the conventional strategy group.
Active SB-P strategy and outcomes
SB occlusion can lead to clinically significant MI and even death. Branch occlusion may affect the PCI procedure directly: SB occlusion prompts interventionalists to urgently restore the branch vessels. During this unexpected episode, rewiring under the intima and suboptimal stent implantation may occur and result in greater rates of in-hospital complications and long-term MACE (2). In the present study, although there was no significant difference in the incidence of MACE within 1 month between groups, active SB-P strategies reduced the incidence of SB occlusion. Although perhaps because of operator experience this was not associated with differences in large MI by treatment group, the rate of periprocedural MI was lower according to post hoc sensitivity analysis when applying the more sensitive WHO or ARC-2 definition in the ATS analysis. Different threshold of biomarkers (creatine kinase–MB or cardiac troponin) were used to identify periprocedural MI and further prognostic significance (14). According to a previous study, any increase in creatine kinase–MB after PCI is associated with a small, but statistically and clinically significant, increase in the subsequent risk for death (15), so different definitions with low to high threshold levels of isoenzyme would provide more useful information on clinical practice. In contrast, long-term follow-up of the present study was valuable to explore clinical impacts of transient SB occlusion during the procedure.
Stratification by the V-RESOLVE score
To simplify assessment of bifurcation lesions in interventional cardiology, numerous classifications and definitions of coronary bifurcation lesions have been proposed (16–19). Among them, the “Medina classification” and “true bifurcation lesion” are widely used. However, none of these classifications or definitions was developed to predict the risk for SB occlusion. In one of our previous studies, “true bifurcation lesion” was not an independent predictor of SB occlusion (20). The V-RESOLVE score, which incorporates 6 independent predictors of SB occlusion, is a validated scoring system to evaluate the risk for SB occlusion and a useful tool for risk prediction of SB occlusion in the present study. V-RESOLVE score ≥12 points has been considered to indicate high risk for SB occlusion: among patients with V-RESOLVE scores ≥12 undergoing the conventional strategy, the rate of SB occlusion ranged from 16.7% to 26.2% (3,5). In the present study, the incidence of SB occlusion in the conventional group was 18.0%, which is consistent with our previous studies and therefore validates the V-RESOLVE score in a prospective study. The results to a certain extent proved that real high-risk bifurcation lesions as identified using the V-RESOLVE score were directly associated with SB occlusion even in the hands of experienced interventionalists proved to be skilled in bifurcation PCI. Thus, the V-RESOLVE score could help even these high-volume operators further reduce the incidence of SB occlusion by stimulating the use of active strategies. However, a future randomized trial comparing V-RESOLVE score–guided PCI with the conventional approach in an “all-comers” bifurcation patient population is needed.
First, this study was prematurely terminated because of slow recruitment (mainly because of a relatively low prevalence of bifurcation lesions with V-RESOLVE scores ≥12), leading to a smaller sample size than planned. However, the post hoc calculation of the conditional power confirmed that the sample size still had enough power. The values of conditional power were higher than 80% in most cases, except for some extreme hypotheses (detailed in Supplemental Table S6).
Second, per the study design, the investigators were not blinded. All adverse clinical events were evaluated and adjudicated by an independent committee. Therefore, the incidence of adverse cardiac events in the present study could be considered dependable.
Third, the 12-month time point to report the MACE endpoint has not been reached, so the preliminary report of 1-month MACE is post hoc and exploratory.
Fourth, the overall rates of the proximal optimization technique were low and as such could have influenced the results.
Finally, in the present study, the risk assessment of SB occlusion relied solely on coronary angiography, with no intravascular imaging or functional evaluation. Use of a risk-evaluating system involving parameters of intravascular imaging and functional evaluation is warranted.
In patients with high risk of SB occlusion (V-RESOLVE score ≥12 points), an active SB-P strategy is superior to a conventional strategy in reducing SB occlusion and loss of SB flow.
WHAT IS KNOWN? Accurate prediction of SB occlusion after MV stenting followed by the use of specific strategies to prevent occlusion would be beneficial during bifurcation intervention. No randomized trials have compared SB occlusion between an active SB-P strategy and the conventional strategy in high-risk patients.
WHAT IS NEW? The present study, randomizing patients at high risk for SB compromise, demonstrated that an active SB-P strategy, especially the jailed balloon technique for small SBs, was not only feasible but was also associated with significantly lower incidence of SB occlusion.
WHAT IS NEXT? Long-term follow-up of this study is needed, and a large-scale randomized trial with a clinical primary endpoint will be initiated soon to determine the real clinical benefit of using the V-RESOLVE score to guide complex bifurcation PCI.
↵∗ Drs. Dou, D. Zhang, and Pan contributed equally to this work.
The CIT-RESOLVE is an investigator-initiated study and was jointly supported by research grants from the Investigator Sponsored Studies project (Abbott Vascular; study number COR-10498) and the Peking Union Medical College Youth Fund and Fundamental Research Funds for the Central Universities (grant 3332016130). The investigators are solely responsible for the design, conduct, data analysis and interpretation of this study, writing the manuscript, and the decision to submit the manuscript for publication, without any influence from the financial supporters. The authors have reported that they have no relationships relevant to the contents of this paper to disclose.
The authors attest they are in compliance with human studies committees and animal welfare regulations of the authors’ institutions and Food and Drug Administration guidelines, including patient consent where appropriate. For more information, visit the JACC: Cardiovascular Interventions author instructions page.
- Abbreviations and Acronyms
- Academic Research Consortium
- as-treated set
- confidence interval
- major adverse cardiac event(s)
- myocardial infarction
- main vessel
- percutaneous coronary intervention
- reference vessel diameter
- side branch
- side branch protection
- World Health Organization
- Received October 4, 2019.
- Revision received January 27, 2020.
- Accepted January 28, 2020.
- 2020 American College of Cardiology Foundation
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