RESUMEN
BACKGROUND: There is limited data on predicting successful chronic total occlusion crossing using primary antegrade wiring (AW). OBJECTIVES: The aim of this study was to develop and validate a machine learning (ML) prognostic model for successful chronic total occlusion crossing using primary AW. METHODS: We used data from 12,136 primary AW cases performed between 2012 and 2023 at 48 centers in the PROGRESS CTO registry (Prospective Global Registry for the Study of Chronic Total Occlusion Intervention; NCT02061436) to develop 5 ML models. Hyperparameter tuning was performed for the model with the best performance, and the SHAP (SHapley Additive exPlanations) explainer was implemented to estimate feature importance. RESULTS: Primary AW was successful in 6,965 cases (57.4%). Extreme gradient boosting was the best performing ML model with an average area under the receiver-operating characteristic curve of 0.775 (± 0.010). After hyperparameter tuning, the average area under the receiver-operating characteristic curve of the extreme gradient boosting model was 0.782 in the training set and 0.780 in the testing set. Among the factors examined, occlusion length had the most significant impact on predicting successful primary AW crossing followed by blunt/no stump, presence of interventional collaterals, vessel diameter, and proximal cap ambiguity. In contrast, aorto-ostial lesion location had the least impact on the outcome. A web-based application for predicting successful primary AW wiring crossing is available online (PROGRESS-CTO website) (https://www.progresscto.org/predict-aw-success). CONCLUSIONS: We developed an ML model with 14 features and high predictive capacity for successful primary AW in chronic total occlusion percutaneous coronary intervention.
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Oclusión Coronaria , Aprendizaje Automático , Intervención Coronaria Percutánea , Valor Predictivo de las Pruebas , Sistema de Registros , Humanos , Oclusión Coronaria/diagnóstico por imagen , Oclusión Coronaria/terapia , Oclusión Coronaria/fisiopatología , Masculino , Femenino , Resultado del Tratamiento , Enfermedad Crónica , Anciano , Persona de Mediana Edad , Intervención Coronaria Percutánea/efectos adversos , Reproducibilidad de los Resultados , Factores de Riesgo , Técnicas de Apoyo para la Decisión , Factores de TiempoAsunto(s)
Oclusión Coronaria , Intervención Coronaria Percutánea , Enfermedades Vasculares , Humanos , Calcio , Resultado del Tratamiento , Disección , Oclusión Coronaria/diagnóstico por imagen , Oclusión Coronaria/terapia , Enfermedad Crónica , Intervención Coronaria Percutánea/efectos adversos , Angiografía CoronariaRESUMEN
BACKGROUND: The contemporary frequency and outcomes of antegrade dissection and re-entry (ADR) for chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have received limited study. OBJECTIVES: The aim of this study was to determine the frequency and outcomes of ADR use in a large multicenter CTO PCI registry. METHODS: The characteristics and outcomes of ADR were examined among 12,568 patients who underwent 12,841 CTO PCIs at 46 U.S. and non-U.S. centers between 2012 and 2023. RESULTS: ADR was used in 2,385 of the procedures (18.6%). ADR use declined from 37.9% in 2012 to 14.5% in 2022 (P < 0.001). Patients in whom ADR was used had a high prevalence of comorbidities. Compared with cases that did not use ADR, ADR cases had more complex angiographic characteristics, higher mean J-CTO (Multicenter CTO Registry in Japan) score (2.94 ± 1.11 vs 2.23 ± 1.26; P < 0.001), lower technical success (77.0% vs 89.3%; P < 0.001), and higher in-hospital major adverse cardiac events (3.7% vs 1.6%; P < 0.001). The use of the CrossBoss declined from 71% in 2012 to 1.4% in 2022 and was associated with higher technical success (87%) compared with wire-based techniques (73%). The Stingray device displayed higher technical success (86%) compared with subintimal tracking and re-entry (STAR) (74%) and limited antegrade subintimal tracking (78%); however, its use has been decreasing, with STAR becoming the most used re-entry technique in 2022 (44% STAR vs 38% Stingray). CONCLUSIONS: The use of ADR has been decreasing. ADR was used in more complex lesions and was associated with lower technical success and higher major adverse cardiac events compared with non-ADR cases. There has been a decrease in Stingray use and an increase in the use of STAR for re-entry.
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Oclusión Coronaria , Intervención Coronaria Percutánea , Humanos , Resultado del Tratamiento , Oclusión Coronaria/diagnóstico por imagen , Oclusión Coronaria/terapia , Oclusión Coronaria/etiología , Angiografía Coronaria , Disección , Sistema de Registros , Enfermedad Crónica , Factores de RiesgoRESUMEN
We examined the outcomes of the Carlino technique in chronic total occlusion (CTO) percutaneous coronary interventions (PCIs). We analyzed the baseline clinical and angiographic characteristics and outcomes of 128 CTO PCIs that included the Carlino technique at 22 US and no-US centers between 2016 and 2023. The Carlino technique was used in 128 (2.8%) of 4,508 cases that used anterograde dissection and reentry (78.9%) or the retrograde approach (21.1%) during the study period, and it increased steadily over time (from 0.0% in 2016 to 8.3% in 2023). The mean patient age was 65.6 ± 9.7 years, and 88.7% of the patients were men with high prevalence of hypertension (89.1%) and dyslipidemia (80.2%). The Carlino technique was more commonly used in cases with moderate to severe calcification (77.2% vs 55.5%, p <0.001) with higher J-CTO (3.3 ± 0.9 vs 3.0 ± 1.1, p = 0.007), Prospective Global Registry for the Study of Chronic Total Occlusion Intervention (PROGRESS-CTO) (1.7 ± 1.0 vs 1.4 ± 1.0, p = 0.001), PROGRESS-CTO Mortality (2.6 ± 0.9 vs 2.0 ± 0.9, p = 0.013) and PROGRESS-CTO Perforation (3.7 ± 1.1 vs 3.5 ± 1.0, p = 0.029) scores. Carlino cases had longer procedure and fluoroscopy time, and higher contrast volume and radiation dose. Carlino cases had lower technical (65.6% vs 78.5%, p <0.001) and procedural (63.3% vs 76.3%, p <0.001) success, similar major adverse cardiac events (6.2% vs 3.2%, p = 0.101) and higher incidence of pericardiocentesis (3.9% vs 1.3%, p = 0.042), perforation (18.0% vs 8.9%, p = 0.001) and contrast-induced acute kidney injury (2.3% vs 0.4%, p = 0.012). The Carlino technique was associated with higher procedural success when used for retrograde crossing (81.5% vs 58.4%, p = 0.047). The Carlino technique is increasingly being used in CTO PCI especially for higher complexity lesions.
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Oclusión Coronaria , Intervención Coronaria Percutánea , Masculino , Humanos , Persona de Mediana Edad , Anciano , Femenino , Intervención Coronaria Percutánea/métodos , Factores de Riesgo , Estudios Prospectivos , Oclusión Coronaria/diagnóstico , Oclusión Coronaria/cirugía , Oclusión Coronaria/etiología , Resultado del Tratamiento , Angiografía Coronaria/métodos , Factores de Tiempo , Enfermedad Crónica , Sistema de RegistrosRESUMEN
BACKGROUND: Coronary calcification is common and increases the difficulty of chronic total occlusion (CTO) percutaneous coronary intervention (PCI). METHODS: We examined the impact of calcium on procedural outcomes of 13,079 CTO PCIs performed in 12,799 patients at 46 US and non-US centers between 2012 and 2023. RESULTS: Moderate or severe calcification was present in 46.6% of CTO lesions. Patients whose lesions were calcified were older and more likely to have had prior coronary artery bypass graft surgery. Calcified lesions were more complex with higher J-CTO score (3.0 ± 1.1 vs. 1.9 ± 1.2; p < 0.001) and lower technical (83.0% vs. 89.9%; p < 0.001) and procedural (81.0% vs. 89.1%; p < 0.001) success rates compared with mildly calcified or non-calcified CTO lesions. The retrograde approach was more commonly used among cases with moderate/severe calcification (40.3% vs. 23.5%; p < 0.001). Balloon angioplasty (76.6%) was the most common lesion preparation technique for calcified lesions, followed by rotational atherectomy (7.3%), laser atherectomy (3.4%) and, intravascular lithotripsy (3.4%). The incidence of major adverse cardiovascular events (MACE) was higher in cases with moderate or severe calcification (3.0% vs. 1.2%; p < 0.001), as was the incidence of perforation (6.5% vs. 3.4%; p < 0.001). On multivariable analysis, the presence of moderate/severe calcification was independently associated with lower technical success (odds ratio, OR = 0.73, 95% CI: 0.63-0.84) and higher MACE (OR = 2.33, 95% CI: 1.66-3.27). CONCLUSIONS: Moderate/severe calcification was present in nearly half of CTO lesions, and was associated with higher utilization of the retrograde approach, lower technical and procedural success rates, and higher incidence of in-hospital MACE.
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Calcinosis , Oclusión Coronaria , Intervención Coronaria Percutánea , Humanos , Intervención Coronaria Percutánea/efectos adversos , Intervención Coronaria Percutánea/métodos , Calcio , Factores de Riesgo , Oclusión Coronaria/diagnóstico , Oclusión Coronaria/cirugía , Oclusión Coronaria/epidemiología , Angiografía Coronaria/métodos , Calcinosis/complicaciones , Enfermedad Crónica , Resultado del Tratamiento , Sistema de RegistrosRESUMEN
Chronic total occlusion (CTO) percutaneous coronary interventions (PCIs) can be lengthy procedures. We sought to investigate the effect of procedural time on CTO PCI outcomes. We examined the procedural time required for the various steps of CTO PCI in 6,442 CTO PCIs at 40 US and non-US centers between 2012 and 2022. The mean and median procedure times were 129 ± 76 and 112 minutes, respectively, with no significant change over time. The median times from access to wire insertion, guidewire manipulation time, and post crossing were 20, 32, and 53 minutes, respectively. Lesions crossed in <30 minutes were less complex, as reflected by lower Japanese CTO score (1.89 ± 1.19, p <0.001) than lesions that were not successfully crossed (2.88 ± 1.22) and lesions that were crossed in ≥30 minutes (2.85 ± 1.13). The likelihood of successful crossing if crossing was not achieved after 30, 90, and 180 minutes were a 76.7%, 60.7%, and 42.7%, respectively. The parameters independently associated with ≥30 minutes guidewire manipulation time in patients with a primary antegrade approach included left anterior descending target vessel, proximal cap ambiguity, blunt/no stump, occlusion length, previous failed attempt, medium/severe calcification, and medium/severe tortuosity. The mean duration of CTO PCI is approximately 2 hours (â¼20% of time for access to wire insertion, â¼30% wire manipulation time, and â¼50% postwiring time). Guidewire crossing time was shorter in less complex lesions and in cases without complications.
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Calcinosis , Oclusión Coronaria , Intervención Coronaria Percutánea , Humanos , Intervención Coronaria Percutánea/métodos , Resultado del Tratamiento , Oclusión Coronaria/diagnóstico , Oclusión Coronaria/cirugía , Factores de Tiempo , Enfermedad Crónica , Angiografía Coronaria/métodos , Sistema de RegistrosRESUMEN
The impact of a previous failure on procedural techniques and outcomes of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) has received limited study. We examined the clinical and angiographic characteristics and procedural outcomes of 9,393 patients who underwent 9,560 CTO PCIs at 42 United States and non-United States centers between 2012 and 2022. A total of 1,904 CTO lesions (20%) had a previous failed PCI attempt. Patients who underwent reattempt CTO PCI were more likely to have a family history of coronary artery disease (37% vs 31%, p <0.001) and dyslipidemia (87.9% vs 84.3%, p <0.001) but were less likely to have heart failure (25.1% vs 29.5%; p <0.001) and cerebrovascular disease (8.7% vs 10.4%, p = 0.04). Patients with previous failure had a higher Japanese CTO (3.33 ± 1.16 vs 2.12 ± 1.19, p <0.001) score and required longer procedure (120 vs 111 minutes, p <0.001) and fluoroscopy (46.9 vs 40.4 minutes, p <0.001) times and higher air kerma radiation dose (2.3 vs 2.1 gray, p = 0.013). Technical success rates (84.3% vs 86.5%, p = 0.011) were lower in patients with a previous failure compared with patients who underwent first-attempt CTO PCI with no significant difference in in-hospital major adverse cardiac events. After adjusting for potential confounders, a previous failure was not associated with technical failure. Operators performing >30 CTO PCIs annually were more likely to achieve technical success in patients with previous failure. In conclusion, a previous failed CTO PCI attempt was associated with higher lesion complexity, longer procedure time, and lower technical success; however, the association with lower technical success did not remain significant in multivariable analysis.
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Oclusión Coronaria , Intervención Coronaria Percutánea , Humanos , Resultado del Tratamiento , Factores de Riesgo , Intervención Coronaria Percutánea/métodos , Oclusión Coronaria/diagnóstico , Oclusión Coronaria/cirugía , Oclusión Coronaria/etiología , Angiografía Coronaria/métodos , Enfermedad Crónica , Sistema de RegistrosRESUMEN
Multivessel coronary artery disease (CAD) is associated with worse outcomes across the spectrum of clinical presentations. The prognostic implications of completeness of revascularization in CAD patients, especially those with chronic coronary syndromes (CCS), remain highly debated. This is largely due to the use of non-standardized definitions for complete revascularization (CR) and incomplete revascularization (ICR) within previously published studies, lack of randomized clinical data, varying revascularization methods and heterogenous study populations. In particular, the utility and effectiveness of PCI-mediated CR for CCS remains unknown. In this review, we discuss the various definitions used for CR vs. ICR, highlight the rationale for pursuing CR and summarise the current literature regarding the effects of PCI-mediated CR on clinical outcomes in patients with CCS.
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Enfermedad de la Arteria Coronaria , Intervención Coronaria Percutánea , Humanos , Intervención Coronaria Percutánea/efectos adversos , Intervención Coronaria Percutánea/métodos , Resultado del Tratamiento , Enfermedad de la Arteria Coronaria/diagnóstico por imagen , Enfermedad de la Arteria Coronaria/cirugía , Pronóstico , Procedimientos Quirúrgicos VascularesRESUMEN
BACKGROUND: Whether saphenous vein grafts (SVGs) should be occluded after successful chronic total occlusion (CTO) percutaneous coronary intervention (PCI) of the corresponding native vessel remains controversial. METHODS: We analyzed the clinical and angiographic characteristics and procedural outcomes of 51 patients who underwent SVG occlusion following successful CTO-PCI of the corresponding native vessel between 2015 and 2022 at 14 centers. RESULTS: Mean patient age was 71 ± 8 years and 80% were men. The most common CTO target vessel was the right coronary artery (41%), followed by the left circumflex (37%). Retrograde crossing through the SVG was the successful crossing strategy in 40 cases (78%). SVG occlusion was achieved with coils (1.9 ± 1.0) in 35 of 51 patients (69%) and vascular plugs in the other 16 cases (31%). All procedures were technically successful and the SVG was occluded completely (TIMI 0 flow) in 38 of the cases (75%), with the remaining cases having TIMI 1 flow. Follow-up was available for 37 patients (73%); during a mean follow-up of 312 days from CTO-PCI, the incidence of target-lesion failure due to restenosis was 5.4% (n = 2) with no other major events reported. CONCLUSION: Following native vessel CTO-PCI, SVG occlusion is often performed and is associated with favorable mid-term outcomes.
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Intervención Coronaria Percutánea , Humanos , Persona de Mediana Edad , Anciano , Intervención Coronaria Percutánea/efectos adversos , Vena SafenaRESUMEN
INTRODUCTION: Thrombolysis is currently reserved for ST-elevation myocardial infarction (STEMI) patients who cannot access timely percutaneous coronary intervention (PCI). In case of failed thrombolysis, rescue PCI is a viable option. Substantial data concerning the outcomes in terms of infarct size and myocardial function after rescue PCI are lacking. METHODS: Forty patients treated with rescue PCI underwent serial contrast-enhanced cardiac magnetic resonance imaging (CMR) at 1 week, 3 months and 6 months from the index STEMI. Angiographic images were reviewed to assess Thrombolysis in Myocardial Infarction (TIMI) blood flow and TIMI Myocardial Blush Grade (TMBG) in the infarct related artery after PCI. RESULTS: Patients with lower TMBG at the end of procedure, but not patients with worse TIMI flow, had lower left ventricular ejection fraction (LVEF) and higher volume of late gadolinium enhancement (LGE) on baseline CMR (44 ± 13% vs 52 ± 9%, p = 0.026, and 41 ± 21 ml vs 26 ± 12, p = 0.030, respectively). Patients with lower TMBG remained with significantly lower LVEF at 6 months follow up (48 ± 16% vs 59 ± 14, p = 0.049). CONCLUSION: TMBG after rescue PCI is associated with reduced LVEF and increased LGE burden. As TMBG is a known marker of microvascular damage after STEMI, novel strategies aimed at improving microvascular function in the setting of rescue PCI are needed to improve the outcomes in this patient population.
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Intervención Coronaria Percutánea , Infarto del Miocardio con Elevación del ST , Angioplastia , Sonrojo , Medios de Contraste , Angiografía Coronaria/métodos , Circulación Coronaria/fisiología , Gadolinio , Humanos , Imagen por Resonancia Magnética/métodos , Espectroscopía de Resonancia Magnética , Infarto del Miocardio con Elevación del ST/diagnóstico por imagen , Infarto del Miocardio con Elevación del ST/cirugía , Volumen Sistólico , Resultado del Tratamiento , Función Ventricular IzquierdaRESUMEN
BACKGROUND: Patients on uniterrupted chronic oral anticoagulation (OAC) therapy are at high-risk of bleeding during cardiac catheterization. We aimed to investigate the safety and efficacy of the StatSeal® disc for adjunct hemostasis in patients undergoing transradial coronary angiography under uninterrupted OAC therapy. METHODS: Patients who underwent transradial cardiac catheterization without interrupted OAC therapy were included in this study. RESULTS: Among 180 patients, 85 (47.2%) patients were on warfarin and 95 (52.8%) patients on novel oral anticoagulants (NOACs). Patients on NOACs were older (72.9 ± 9.6 versus 69.7 ± 10.8 years, P < 0.001) and had more atrial fibrillation/flutter (94.7% versus 62.4%, P < 0.001), whereas patients on Warfarin were more often women (43.5% versus 26.3%, P = 0.02) and had mechanical heart valves (27.1% versus 0%, P < 0.001). Intravenous unfractioned heparin (UFH) was administered in 96.5% of patients on warfarin (3799 ± 1342 units) and 93.7% patients on NOACs (4028 ± 1362 units), P = 0.27. There were no differences in terms of type and sheath size and the need for ad hoc coronary intervention. Time-to-first release of the hemostatic wristband was 56.2 ± 12.6 min and complete hemostasis was achieved in 71.1 ± 13.0 min, with shorter times among patients on NOACs (54.1 ± 11.7 and 58.5 ± 13.2 min, 68.9 ± 11.7 versus 73.6 ± 14.0 min, P = 0.02, for both). There were no significant differences in terms of bleeding. There was no radial artery occlusion among 112 participants who underwent color Doppler ultrasound. CONCLUSION: The present study shows that in patients undergoing transradial coronary angiogram under contemporary uninterrupted OAC therapy and periprocedural administration of UFH, the use of StatSeal® disc for adjunctive hemostasis was associated with short times to complete hemostasis.
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Anticoagulantes , Arteria Radial , Administración Oral , Anticoagulantes/efectos adversos , Femenino , Humanos , Arteria Radial/diagnóstico por imagen , Resultado del Tratamiento , WarfarinaRESUMEN
Chronic total occlusions are considered the most complex coronary lesion in interventional cardiology. The absence of visible lumen on angiography obscures the vessel course and makes vessel wiring unlikely with conventional techniques. Often a source of severe ischemia, chronic occlusions are also markers of advanced atherosclerosis that brings other complex features including lesion length, bifurcations, calcification, adverse vessel remodelling, distal disease, and anatomic distortion from previous bypass grafting. Often advanced atherosclerosis is associated with patient characteristics like left ventricular dysfunction, previous coronary bypass surgery, or multivessel disease that increase procedural demands and hazards. To accommodate these challenges new techniques and dedicated technologies have been developed. When applied to appropriate patients, these advances have improved procedural success, safety, and outcomes. Our aim is to provide the general cardiologist with an overview of these advances that can serve as a basis for counselling patients considered for revascularization.
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Aterosclerosis , Oclusión Coronaria , Intervención Coronaria Percutánea , Aterosclerosis/etiología , Enfermedad Crónica , Angiografía Coronaria , Oclusión Coronaria/diagnóstico , Oclusión Coronaria/cirugía , Predicción , Humanos , Intervención Coronaria Percutánea/efectos adversos , Resultado del TratamientoRESUMEN
BACKGROUND: As a result of the COVID-19 pandemic first wave, reductions in ST-elevation myocardial infarction (STEMI) invasive care, ranging from 23% to 76%, have been reported from various countries. Whether this change had any impact on coronary angiography (CA) volume or on mechanical support device use for STEMI and post-STEMI mechanical complications in Canada is unknown. METHODS: We administered a Canada-wide survey to all cardiac catheterization laboratory directors, seeking the volume of CA use for STEMI performed during the period from March 1 2020 to May 31, 2020 (pandemic period), and during 2 control periods (March 1, 2019 to May 31, 2019 and March 1, 2018 to May 31, 2018). The number of left ventricular support devices used, as well as the number of ventricular septal defects and papillary muscle rupture cases diagnosed, was also recorded. We also assessed whether the number of COVID-19 cases recorded in each province was associated with STEMI-related CA volume. RESULTS: A total of 41 of 42 Canadian catheterization laboratories (98%) provided data. There was a modest but statistically significant 16% reduction (incidence rate ratio [IRR] 0.84; 95% confidence interval 0.80-0.87) in CA for STEMI during the first wave of the pandemic, compared to control periods. IRR was not associated with provincial COVID-19 caseload. We observed a 26% reduction (IRR 0.74; 95% confidence interval 0.61-0.89) in the use of intra-aortic balloon pump use for STEMI. Use of an Impella pump and mechanical complications from STEMI were exceedingly rare. CONCLUSIONS: We observed a modest 16% decrease in use of CA for STEMI during the pandemic first wave in Canada, lower than the level reported in other countries. Provincial COVID-19 caseload did not influence this reduction.
INTRODUCTION: Après la première vague de la pandémie de COVID-19, de nombreux pays ont déclaré une réduction de 23 % à 76 % des soins invasifs de l'infarctus du myocarde avec élévation du segment ST (STEMI). On ignore si ce changement a entraîné des répercussions sur le volume d'angiographies coronariennes (AC) ou sur l'utilisation des dispositifs d'assistance mécanique lors de STEMI et des complications mécaniques post-STEMI au Canada. MÉTHODES: Nous avons réalisé un sondage pancanadien auprès de tous les directeurs de laboratoire de cathétérisme cardiaque pour obtenir le volume d'utilisation des AC lors des STEMI réalisées durant la période du 1er mars 2020 au 31 mai 2020 (période de pandémie) et durant 2 périodes témoins (1er mars 2019 au 31 mai 2019 et 1er mars 2018 au 31 mai 2018). Le nombre de dispositifs d'assistance ventriculaire gauche utilisés et le nombre de cas de communications interventriculaires et de ruptures du muscle papillaire diagnostiqués ont également été enregistrés. Nous avons aussi évalué si le nombre de cas de COVID-19 enregistrés dans chaque province était associé au volume d'AC liées aux STEMI. RÉSULTATS: Au total, 41 des 42 laboratoires canadiens de cathétérisme (98 %) ont fourni des données. Lors de la comparaison de la première vague de la pandémie aux périodes témoins, nous avons noté une réduction modeste, mais significative, sur le plan statistique de 16 % (ratio du taux d'incidence [RTI] 0,84; intervalle de confiance à 95 % 0,80-0,87) des AC lors de STEMI. Le RTI n'était pas associé au nombre provincial de cas de COVID-19. Nous avons observé une réduction de 26 % (RTI 0,74; intervalle de confiance à 95 % 0,61-0,89) de l'utilisation de pompes à ballonnet intra-aortique lors de STEMI. L'utilisation d'une pompe Impella et les complications mécaniques après les STEMI étaient extrêmement rares. CONCLUSIONS: Nous avons observé une diminution modeste de 16 % de l'utilisation des AC lors de STEMI durant la première vague de la pandémie au Canada, soit une diminution plus faible que ce que les autres pays ont signalé. Le nombre provincial de cas de COVID-19 n'a pas influencé cette réduction.
RESUMEN
Over the past 2 decades, chronic total occlusion (CTO) percutaneous coronary intervention has developed into its own subspecialty of interventional cardiology. Dedicated terminology, techniques, devices, courses, and training programs have enabled progressive advancements. However, only a few randomized trials have been performed to evaluate the safety and efficacy of CTO percutaneous coronary intervention. Moreover, several published observational studies have shown conflicting data. Part of the paucity of clinical data stems from the fact that prior studies have been suboptimally designed and performed. The absence of standardized end points and the discrepancy in definitions also prevent consistency and uniform interpretability of reported results in CTO intervention. To standardize the field, we therefore assembled a broad consortium comprising academicians, practicing physicians, researchers, medical society representatives, and regulators (US Food and Drug Administration) to develop methods, end points, biomarkers, parameters, data, materials, processes, procedures, evaluations, tools, and techniques for CTO interventions. This article summarizes the effort and is organized into 3 sections: key elements and procedural definitions, end point definitions, and clinical trial design principles. The Chronic Total Occlusion Academic Research Consortium is a first step toward improved comparability and interpretability of study results, supplying an increasingly growing body of CTO percutaneous coronary intervention evidence.