Effects of Sacubitril/Valsartan vs Valsartan in De Novo vs Acute on Chronic HFpEF and HFmrEF.

Background: Decompensated heart failure (HF) can be categorized as de novo or worsening of chronic HF. In PARAGLIDE-HF (Prospective comparison of ARNI with ARB Given following stabiLization In DEcompensated HFpEF), among patients with an ejection fraction >40% that stabilized after worsening HF, sacubitril/valsartan led to a significantly greater reduction in N-terminal pro-B-type natriuretic peptide (NT-proBNP) and was associated with clinical benefit compared to valsartan. Objectives: This prespecified analysis characterized patients with de novo vs worsening chronic HF in PARAGLIDE-HF and assessed the interaction between HF chronicity and the effect of sacubitril/valsartan. Methods: Patients were classified as de novo (first diagnosis of HF) or chronic (known HF prior to the index event). Time-averaged proportional change in NT-proBNP from baseline to weeks 4 and 8 was analyzed using an analysis of covariance model. A win ratio consisting of time to cardiovascular death, number and times of HF hospitalizations during follow-up, number and times of urgent HF visits during follow-up, and time-averaged proportional change in NT-proBNP was assessed for each group. Results: Of the 466 participants, 153 (33%) had de novo HF and 313 (67%) had chronic HF. De novo patients had lower rates of atrial fibrillation/flutter and lower creatinine. There was a nonsignificant reduction in NT-proBNP with sacubitril/valsartan vs valsartan for de novo (0.82; 95% CI: 0.62-1.07) and chronic HF (0.88; 95% CI: 0.73-1.07), interaction P = 0.66. The win ratio was nominally in favor of sacubitril/valsartan for both de novo (1.12; 95% CI: 0.70-1.58) and chronic HF (1.24; 95% CI: 0.89-1.71). Conclusions: There is no interaction between HF chronicity and the effect of sacubitril-valsartan.

Sex Differences in Characteristics, Resource Utilization, and Outcomes of Cardiogenic Shock: Data From the Critical Care Cardiology Trials Network (CCCTN) Registry.

BACKGROUND: Sex disparities exist in the management and outcomes of various cardiovascular diseases. However, little is known about sex differences in cardiogenic shock (CS). We sought to assess sex-related differences in the characteristics, resource utilization, and outcomes of patients with CS. METHODS: The Critical Care Cardiology Trials Network is a multicenter registry of advanced cardiac intensive care units (CICUs) in North America. Between 2018 and 2022, each center (N=35) contributed annual 2-month snapshots of consecutive CICU admissions. Patients with CS were stratified as either CS after acute myocardial infarction or heart failure-related CS (HF-CS). Multivariable logistic regression was used for analyses. RESULTS: Of the 22 869 admissions in the overall population, 4505 (20%) had CS. Among 3923 patients with CS due to ventricular failure (32% female), 1235 (31%) had CS after acute myocardial infarction and 2688 (69%) had HF-CS. Median sequential organ failure assessment scores did not differ by sex. Women with HF-CS had shorter CICU lengths of stay (4.5 versus 5.4 days; P<0.0001) and shorter overall lengths of hospital stay (10.9 versus 12.8 days; P<0.0001) than men. Women with HF-CS were less likely to receive pulmonary artery catheters (50% versus 55%; P<0.01) and mechanical circulatory support (26% versus 34%; P<0.0001) compared with men. Women with HF-CS had higher in-hospital mortality than men, even after adjusting for age, illness severity, and comorbidities (34% versus 23%; odds ratio, 1.76 [95% CI, 1.42-2.17]). In contrast, there were no significant sex differences in utilization of advanced CICU monitoring and interventions, or mortality, among patients with CS after acute myocardial infarction. CONCLUSIONS: Women with HF-CS had lower use of pulmonary artery catheters and mechanical circulatory support, shorter CICU lengths of stay, and higher in-hospital mortality than men, even after accounting for age, illness severity, and comorbidities. These data highlight the need to identify underlying reasons driving the differences in treatment decisions, so outcomes gaps in HF-CS can be understood and eliminated.

American Heart Association Cardiogenic Shock Registry: Design and Implementation.

BACKGROUND: Cardiogenic shock is a morbid complication of heart disease that claims the lives of more than 1 in 3 patients presenting with this syndrome. Supporting a unique collaboration across clinical specialties, federal regulators, payors, and industry, the American Heart Association volunteers and staff have launched a quality improvement registry to better understand the clinical manifestations of shock phenotypes, and to benchmark the management patterns, and outcomes of patients presenting with cardiogenic shock to hospitals across the United States. METHODS: Participating hospitals will enroll consecutive hospitalized patients with cardiogenic shock, regardless of etiology or severity. Data are collected through individual reviews of medical records of sequential adult patients with cardiogenic shock. The electronic case record form was collaboratively designed with a core minimum data structure and aligned with Shock Academic Research Consortium definitions. This registry will allow participating health systems to evaluate patient-level data including diagnostic approaches, therapeutics, use of advanced monitoring and circulatory support, processes of care, complications, and in-hospital survival. Participating sites can leverage these data for onsite monitoring of outcomes and benchmarking versus other institutions. The registry was concomitantly designed to provide a high-quality longitudinal research infrastructure for pragmatic randomized trials as well as translational, clinical, and implementation research. An aggregate deidentified data set will be made available to the research community on the American Heart Association's Precision Medicine Platform. On March 31, 2022, the American Heart Association Cardiogenic Shock Registry received its first clinical records. At the time of this submission, 100 centers are participating. CONCLUSIONS: The American Heart Association Cardiogenic Shock Registry will serve as a resource using consistent data structure and definitions for the medical and research community to accelerate scientific advancement through shared learning and research resulting in improved quality of care and outcomes of shock patients.

Association of Sacubitril/Valsartan vs Valsartan With Blood Pressure Changes and Symptomatic Hypotension: the PARAGLIDE-HF Trial.

BACKGROUND: In PARAGLIDE-HF, in patients with ejection fraction (EF) > 40%, stabilized after worsening heart failure (WHF), sacubitril/valsartan led to greater reduction in plasma NT-proBNP levels and was associated with clinical benefit compared to valsartan alone, despite more symptomatic hypotension (SH). Concern about SH may be limiting the use of sacubitril/valsartan in appropriate patients. METHODS: We characterized patients by the occurrence of SH (investigator-reported) after randomization to either sacubitril/valsartan or valsartan. A key trial inclusion criterion was systolic blood pressure (SBP) ≥ 100 mmHg for the preceding 6 hours and no SH. We also compared outcomes based on baseline SBP stratified by the median blood pressure. The primary endpoint was time-averaged proportional change in NT-proBNP levels from baseline through weeks 4 and 8. A secondary hierarchical outcome (win ratio) consisted of: (1) cardiovascular death; (2) hospitalizations due to HF; (3) urgent HF visits; and (4) change in NT-proBNP levels. RESULTS: Among 466 randomized patients, 92 (19.7%) experienced SH (sacubitril/valsartan, n = 56 [24.0%]; valsartan, n = 36 [15.5%]; P = 0.020). The median time to the first SH event was similar between treatment arms (18 days vs 15 days, respectively; P = 0.42) as was the proportion of first SH events classified as serious by investigators. Patients who experienced SH with sacubitril/valsartan were more likely to be white (OR 1.87 [95% CI: 0.31, 11.15]), to have a lower baseline SBP (per 10 mmHg increase, OR 0.68 [95% CI: 0.55, 0.85]), or to have a left ventricular ejection fraction (LVEF) of > 60% (OR 2.21 [95% CI: 1.05, 4.65]). Time-averaged change in NT-proBNP levels did not differ between patients with baseline SBP ≥ 128 mmHg vs SBP < 128 mmHg (interaction, P = 0.43). The composite hierarchical outcome for sacubitril/valsartan in patients with baseline SBP ≥ 128 mmHg had a win ratio of 1.34 ([95% CI: 0.91, 1.99]; P = 0.096) vs SBP < 128 mmHg with a win ratio of 1.09 ([95%CI: 0.73, 1.66]; P = 0 .62; interaction P value = 0.42). CONCLUSION: Among patients with LVEF > 40% stabilized after WHF, incident SH was more common with sacubitril/valsartan compared with valsartan. SH was associated with lower baseline SBP, being white, and having higher LVEF. Treatment benefits with sacubitril/valsartan may be more pronounced in patients with higher baseline SBP and lower LVEF (≤ 60%). (Funded by Novartis Pharmaceutical Corporation; ClinicalTrials.gov number, NCT03988634.).

CD8+ T cell targeting of tumor antigens presented by HLA-E.

The nonpolymorphic major histocompatibility complex E (MHC-E) molecule is up-regulated on many cancer cells, thus contributing to immune evasion by engaging inhibitory NKG2A/CD94 receptors on NK cells and tumor-infiltrating T cells. To investigate whether MHC-E expression by cancer cells can be targeted for MHC-E-restricted T cell control, we immunized rhesus macaques (RM) with rhesus cytomegalovirus (RhCMV) vectors genetically programmed to elicit MHC-E-restricted CD8+ T cells and to express established tumor-associated antigens (TAAs) including prostatic acidic phosphatase (PAP), Wilms tumor-1 protein, or Mesothelin. T cell responses to all three tumor antigens were comparable to viral antigen-specific responses with respect to frequency, duration, phenotype, epitope density, and MHC restriction. Thus, CMV-vectored cancer vaccines can bypass central tolerance by eliciting T cells to noncanonical epitopes. We further demonstrate that PAP-specific, MHC-E-restricted CD8+ T cells from RhCMV/PAP-immunized RM respond to PAP-expressing HLA-E+ prostate cancer cells, suggesting that the HLA-E/NKG2A immune checkpoint can be exploited for CD8+ T cell-based immunotherapies.

Targeted Proteomic Profiling of Cardiogenic Shock in the Cardiac Intensive Care Unit.

BACKGROUND: We sought to characterize circulating protein biomarkers associated with cardiogenic shock (CS) using highly multiplex proteomic profiling. METHODS: This analysis employed a cross-sectional case-control study design using a biorepository of patients admitted to a cardiac intensive care unit between 2017-2020. Cases were patients adjudicated to have CS and controls were those presenting for cardiac critical care without shock, including subsets of patients with isolated hypotension or heart failure (HF). The Olink platform was used to analyze 359 biomarkers with Bonferroni correction. RESULTS: The analysis included 239 patients presenting for cardiac critical care (69 cases with CS, 170 non-shock controls). A total of 63 biomarkers (17.7%) were significantly associated with CS after Bonferroni correction compared with all controls. Of these, nine biomarkers remained significantly associated with CS when separately cross-validated in subsets of controls presenting with isolated hypotension and HF: cathepsin D, fibroblast growth factor (FGF)-21 and -23, growth differentiation factor (GDF)-15, insulin-like growth factor binding protein-1, N-terminal pro-B-type natriuretic peptide, osteopontin, oncostatin-M-specific receptor subunit beta (OSMR), and soluble ST2 protein (sST2). Four biomarkers were identified as providing complementary information for CS diagnosis with development of a multi-marker model: sST2, FGF-23, CTSD, and GDF-15. CONCLUSION: In this pilot study of targeted proteomic profiling in CS, we identified nine biomarkers significantly associated with CS when cross-validated against non-shock controls including those with HF or isolated hypotension, illustrating the potential application of a targeted proteomic approach to identify novel candidates that may support the diagnosis of CS.

Early Serial Assessment of Aggregate Vasoactive Support and Mortality in Cardiogenic Shock: Insights From the Critical Care Cardiology Trials Network Registry.

BACKGROUND: Associations of early changes in vasoactive support with cardiogenic shock (CS) mortality remain incompletely defined. METHODS: The Critical Care Cardiology Trials Network is a multicenter registry of cardiac intensive care units. Patients admitted with CS (2018-2023) had vasoactive dosing assessed at 4 and 24 hours from cardiac intensive care unit admission and quantified by the vasoactive-inotropic score (VIS). Prognostic associations of VIS at both time points, as well as change in VIS from 4 to 24 hours, were examined. Interaction testing was performed based on mechanical circulatory support status. RESULTS: Among 3665 patients, 82% had a change in VIS <10, with 7% and 11% having a ≥10-point increase and decrease from 4 to 24 hours, respectively. The 4 and 24-hour VIS were each associated with cardiac intensive care unit mortality (13%-45% and 11%-73% for VIS <10 to ≥40, respectively; Ptrend <0.0001 for each). Stratifying by the 4-hour VIS, changes in VIS from 4 to 24 hours had a graded association with mortality, ranging from a 2- to >4-fold difference in mortality comparing those with a ≥10-point increase to ≥10-point decrease in VIS (Ptrend <0.0001). The change in VIS alone provided good discrimination of cardiac intensive care unit mortality (C-statistic, 0.72 [95% CI, 0.70-0.75]) and improved discrimination of the 24-hour Sequential Organ Failure Assessment score (0.72 [95% CI, 0.69-0.74] to 0.76 [95% CI, 0.74-0.78]) and the clinician-assessed Society for Cardiovascular Angiography and Interventions shock stage (0.72 [95% CI, 0.70-0.74] to 0.77 [95% CI, 0.75-0.79]). Although present in both groups, the mortality risk associated with VIS was attenuated in patients managed with versus without mechanical circulatory support (odds ratio per 10-point higher 24-hour VIS, 1.36 [95% CI, 1.23-1.49] versus 1.84 [95% CI, 1.69-2.01]; Pinteraction <0.0001). CONCLUSIONS: Early changes in the magnitude of vasoactive support in CS are associated with a gradient of risk for mortality. These data suggest that early VIS trajectory may improve CS prognostication, with the potential to be leveraged for clinical decision-making and research applications in CS.

Pulmonary Artery Diastolic Pressure as a Surrogate for Pulmonary Capillary Wedge Pressure in Cardiogenic Shock.

BACKGROUND: It is common for clinicians to use the pulmonary artery diastolic pressure (PADP) as a surrogate for the pulmonary capillary wedge pressure (PCWP). Here, we determine the validity of this relationship in patients with various phenotypes of cardiogenic shock (CS). METHODS AND RESULTS: In this analysis of the Critical Care Cardiology Trials Network registry, we identified 1225 people admitted with CS who received pulmonary artery catheters. Linear regression, Bland-Altman and receiver operator characteristic analyses were performed to determine the strength of the association between PADP and PCWP in patients with left-, right-, biventricular, and other non-myocardia phenotypes of CS (eg, arrhythmia, valvular stenosis, tamponade). There was a moderately strong correlation between PADP and PCWP in the total population (r = 0.64, n = 1225) and in each CS phenotype, except for right ventricular CS, for which the correlation was weak (r = 0.43, n = 71). Additionally, we found that a PADP ≥ 24 mmHg can be used to infer a PCWP ≥ 18 mmHg with ≥ 90% confidence in all but the right ventricular CS phenotype. CONCLUSIONS: This analysis validates the practice of using PADP as a surrogate for PCWP in most patients with CS; however, it should generally be avoided in cases of right ventricular-predominant CS.

Transcriptomic Profiling at the Maternal-to-Zygotic Transition in Leech, Helobdella austinensis.

The glossiphoniid leech, Helobdella austinensis, is an experimentally tractable member of the superphylum, Lophotrochozoa. Its large embryonic cells, stereotyped asymmetric cell divisions and ex vivo development capabilities makes it a favorable model for studying the molecular and cellular events of a representative spiralian. In this study, we focused on a narrow developmental time window of ~6-8 h, comprising stages just prior to and immediately following zygote deposition. Employing RNA-Seq methodology, we identified differentially expressed transcripts at this fundamental ontogenic boundary, known as the maternal-to-zygotic transition (MZT). Gene expression changes were characterized by the massive degradation of maternal RNAs (~45%) coupled with the rapid transcription of ~5000 zygotic genes (~20% of the genome) in the first mitotic cell cycle. The latter transcripts encoded a mixture of cell maintenance and regulatory proteins that predictably influence downstream developmental events.

Sacubitril/Valsartan in Patients Hospitalized With Decompensated Heart Failure.

BACKGROUND: The efficacy and safety of sacubitril/valsartan in patients hospitalized with heart failure (HF) across the spectrum of left ventricular ejection fraction (EF) has not been described. OBJECTIVES: Data from randomized trials of sacubitril/valsartan in HF patients with EF ≤40% (PIONEER-HF [Comparison of Sacubitril/Valsartan Versus Enalapril on Effect of NT-proBNP in Patients Stabilized From an Acute Heart Failure Episode] trial) and >40% (PARAGLIDE-HF [Prospective comparison of ARNI with ARB Given following stabiLization In DEcompensated HFpEF] trial) following recent worsening heart failure (WHF) were pooled to examine treatment effect across the EF spectrum. METHODS: The PIONEER-HF and PARAGLIDE-HF trials were double-blind, randomized trials of sacubitril/valsartan vs control therapy (enalapril or valsartan, respectively). All participants in the PIONEER-HF trial and 69.5% in the PARAGLIDE-HF trial were enrolled during hospitalization for HF after stabilization. The remainder in the PARAGLIDE-HF trial were enrolled ≤30 days after a WHF event. The primary endpoint of both trials was time-averaged proportional change in N-terminal pro-B-type natriuretic peptide (NT-proBNP) from baseline through weeks 4 and 8. Adjudicated clinical endpoints were analyzed through the end of follow-up, adjusting for trial. RESULTS: The pooled analysis included 1,347 patients (881 from PIONEER-HF, 466 from PARAGLIDE-HF). Baseline characteristics included median age 66 years, 36% women, 31% Black, 34% de novo HF, and median EF 30%. The reduction in NT-proBNP was 24% greater with sacubitril/valsartan vs control therapy (n = 1,130; ratio of change = 0.76; 95% CI: 0.69-0.83; P < 0.0001). Cardiovascular death or hospitalization for HF was reduced by 30% with sacubitril/valsartan vs control therapy (HR: 0.70; 95% CI: 0.54-0.91; P = 0.0077). This effect was consistent across the spectrum of EF ≤60%. Sacubitril/valsartan increased symptomatic hypotension (risk ratio: 1.35; 95% CI: 1.05-1.72). CONCLUSIONS: In patients stabilized after WHF, sacubitril/valsartan led to a greater reduction in plasma NT-proBNP and improved clinical outcome compared with control therapy, in particular across the spectrum of EF ≤60%. (Comparison of Sacubitril/Valsartan Versus Enalapril on Effect of NT-proBNP in Patients Stabilized From an Acute Heart Failure Episode [PIONEER-HF]; NCT02554890; Changes in NT-proBNP, Safety, and Tolerability in HFpEF Patients With a WHF Event [HFpEF Decompensation] Who Have Been Stabilized and Initiated at the Time of or Within 30 Days Post-decompensation [PARAGLIDE-HF]; NCT03988634).

Training Paradigms in Critical Care Cardiology: A Scoping Review of Current Literature.

Background: Over the past decade there has been increasing interest in critical care medicine (CCM) training for cardiovascular medicine (CV) physicians either in isolation (separate programs in either order [CV/CCM], integrated critical care cardiology [CCC] training) or hybrid training with interventional cardiology (IC)/heart failure/transplant (HF) with targeted CCC training. Objective: To review the contemporary landscape of CV/CCM, CCC, and hybrid training. Methods: We reviewed the literature from 2000-2022 for publications discussing training in any combination of internal medicine CV/CCM, CCC, and hybrid training. Information regarding training paradigms, scope of practice and training, duration, sequence, and milestones was collected. Results: Of the 2,236 unique citations, 20 articles were included. A majority were opinion/editorial articles whereas two were surveys. The training pathways were classified into - (i) specialty training in both CV (3 years) and CCM (1-2 years) leading to dual American Board of Internal Medicine (ABIM) board certification, or (ii) base specialty training in CV with competencies in IC, HF or CCC leading to a non-ABIM certificate. Total fellowship duration varied between 4-7 years after a three-year internal medicine residency. While multiple articles commented on the ability to integrate the fellowship training pathways into a holistic and seamless training curriculum, few have highlighted how this may be achieved to meet competencies and standards. Conclusions: In 20 articles describing CV/CCM, CCC, and hybrid training, there remains significant heterogeneity on the standardized training paradigms to meet training competencies and board certifications, highlighting an unmet need to define CCC competencies.

Modes of Death in Patients with Cardiogenic Shock in the Cardiac Intensive Care Unit: A Report from the Critical Care Cardiology Trials Network.

BACKGROUND: There are limited data on how patients with cardiogenic shock (CS) die. METHODS: The Critical Care Cardiology Trials Network is a research network of cardiac intensive care units coordinated by the Thrombolysis In Myocardial Infarction (TIMI) Study Group (Boston, MA). Using standardized definitions, site investigators classified direct modes of in-hospital death for CS admissions (October 2021 to September 2022). Mutually exclusive categories included 4 modes of cardiovascular death and 4 modes of noncardiovascular death. Subgroups defined by CS type, preceding cardiac arrest (CA), use of temporary mechanical circulatory support (tMCS), and transition to comfort measures were evaluated. RESULTS: Among 1068 CS cases, 337 (31.6%) died during the index hospitalization. Overall, the mode of death was cardiovascular in 82.2%. Persistent CS was the dominant specific mode of death (66.5%), followed by arrhythmia (12.8%), anoxic brain injury (6.2%), and respiratory failure (4.5%). Patients with preceding CA were more likely to die from anoxic brain injury (17.1% vs 0.9%; P < .001) or arrhythmia (21.6% vs 8.4%; P < .001). Patients managed with tMCS were more likely to die from persistent shock (P < .01), both cardiogenic (73.5% vs 62.0%) and noncardiogenic (6.1% vs 2.9%). CONCLUSIONS: Most deaths in CS are related to direct cardiovascular causes, particularly persistent CS. However, there is important heterogeneity across subgroups defined by preceding CA and the use of tMCS.

Variation in risk-adjusted cardiac intensive care unit (CICU) length of stay and the association with in-hospital mortality: An analysis from the Critical Care Cardiology Trials Network (CCCTN) registry.

BACKGROUND: Previous studies have suggested that there is wide variability in cardiac intensive care unit (CICU) length of stay (LOS); however, these studies are limited by the absence of detailed risk assessment at the time of admission. Thus, we evaluated inter-hospital differences in CICU LOS, and the association between LOS and in-hospital mortality. METHODS: Using data from the Critical Care Cardiology Trials Network (CCCTN) registry, we included 22,862 admissions between 2017 and 2022 from 35 primarily tertiary and quaternary CICUs that captured consecutive admissions in annual 2-month snapshots. The primary analysis compared inter-hospital differences in CICU LOS, as well as the association between CICU LOS and all-cause in-hospital mortality using a Fine and Gray competing risk model. RESULTS: The overall median CICU LOS was 2.2 (1.1-4.8) days, and the median hospital LOS was 5.9 (2.8-12.3) days. Admissions in the longest tertile of LOS tended to be younger with higher rates of pre-existing comorbidities, and had higher Sequential Organ Failure Assessment (SOFA) scores, as well as higher rates of mechanical ventilation, intravenous vasopressor use, mechanical circulatory support, and renal replacement therapy. Unadjusted all-cause in-hospital mortality was 9.3%, 6.7%, and 13.4% in the lowest, intermediate, and highest CICU LOS tertiles. In a competing risk analysis, individual patient CICU LOS was correlated (r2 = 0.31) with a higher risk of 30-day in-hospital mortality. The relationship remained significant in admissions with heart failure, ST-elevation myocardial infarction and non-ST segment elevation myocardial infarction. CONCLUSIONS: In a large registry of academic CICUs, we observed significant variation in CICU LOS and report that LOS is independently associated with all-cause in-hospital mortality. These findings could potentially be used to improve CICU resource utilization planning and refine risk prognostication in critically ill cardiovascular patients.

Prioritizing Non-Carbon Dioxide Removal Mitigation Strategies Could Reduce the Negative Impacts Associated with Large-Scale Reliance on Negative Emissions.

Carbon dioxide removal (CDR) is necessary for reaching net zero emissions, with studies showing potential deployment at multi-GtCO2 scale by 2050. However, excessive reliance on future CDR entails serious risks, including delayed emissions cuts, lock-in of fossil infrastructure, and threats to sustainability from increased resource competition. This study highlights an alternative pathway─prioritizing near-term non-CDR mitigation and minimizing CDR dependence. We impose a 1 GtCO2 limit on global novel CDR deployment by 2050, forcing aggressive early emissions reductions compared to 8-22 GtCO2 in higher CDR scenarios. Our results reveal that this low CDR pathway significantly decreases fossil fuel use, greenhouse gas (GHG) emissions, and air pollutants compared to higher CDR pathways. Driving rapid energy transitions eases pressures on land (including food cropland), water, and fertilizer resources required for energy and negative emissions. However, these sustainability gains come with higher mitigation costs from greater near-term low/zero-carbon technology deployment for decarbonization. Overall, this work provides strong evidence for maximizing non-CDR strategies such as renewables, electrification, carbon neutral/negative fuels, and efficiency now rather than betting on uncertain future CDR scaling. Ambitious near-term mitigation in this decade is essential to prevent lock-in and offer the best chance of successful deep decarbonization. Our constrained CDR scenario offers a robust pathway to achieving net zero emissions with limited sustainability impacts.