Circulation最新文献

Ambient temperature is a key environmental driver of cardiovascular health. With rising global temperatures and increasing frequency, intensity, and duration of extreme temperature events, understanding the cardiovascular impacts of nonoptimal temperature is more urgent than ever. Short-term exposures to both heat and cold increase the risk of cardiovascular events, including myocardial infarction, stroke, heart failure decompensation, arrhythmias, and sudden cardiac death. Climate, built environment, socioeconomic variables, physiological vulnerability, and systemic inequities exacerbate these risks. There is also a growing appreciation of the importance of contextual factors such as geographic location, housing, occupation, and individual-level exposure. A range of biological mechanisms, including autonomic and neurohormonal activation, endothelial dysfunction, inflammation, hemoconcentration, and impaired thermoregulation, mediate temperature-related cardiovascular risk. Nonoptimal temperatures affect not only the incidence of cardiovascular disease but also health care access and delivery. They can increase demand for emergency care, disrupt operations, and pose challenges to the resilience and sustainability of health systems. Meanwhile, cardiovascular care contributes significantly to health care-related greenhouse gas emissions, highlighting a paradox in which efforts to protect cardiovascular health can indirectly contribute to climate-driven risks. This scientific statement synthesizes current knowledge of the relationship between nonoptimal temperature and cardiovascular health, highlights inequalities in exposure and outcomes, and identifies actionable strategies at the individual, community, health system, and public policy levels. Last, this scientific statement outlines significant research gaps and future priorities, including the need for improved exposure assessment, better understanding and measurement of the impact of long-term exposures, interactions with medications and coexposures, and identification of risk modifiers. Coordinated action is needed in research, clinical practice, and policy to mitigate the rising risks of nonoptimal temperatures on cardiovascular health in a changing climate.

Background: Heart failure (HF) is a significant global health problem. Left ventricular assist device (LVAD) implantation serves as a bridge for patients awaiting heart transplantation. Intriguingly, LVAD support often improves cardiac histology and function, sometimes enough to avoid transplantation after LVAD removal. However, the cellular programs underlying this recovery remain unclear.

Methods: Myocardial tissues were obtained from patients with HF at the time of LVAD implantation (pre LVAD) and explantation (post LVAD) for histological analysis and single-nucleus RNA sequencing. A murine model of HF recovery, combined with lineage tracing studies, was employed to define cellular sources of vascular repair. Cardiac function, fibrosis, and vascular density were assessed using echocardiography, histology, and fluorescent microsphere perfusion. A patient-derived cardiac nonmyocyte culture system was established to interrogate mechanisms of cell fate regulation.

Results: Post-LVAD myocardial tissues exhibited reduced fibrosis and increased capillary density compared with pre-LVAD samples. Across samples, fibroblast abundance was inversely correlated with endothelial cell abundance, consistent with enhanced angiogenesis during recovery. Single-nucleus RNA sequencing identified a fibroblast subset predisposed to undergo mesenchymal-to-endothelial transition, acquiring an endothelial cell identity. Additionally, nonmyocytes from pre-LVAD hearts proliferated poorly and failed to form vascular structures, whereas nonmyocytes from post-LVAD hearts displayed greater proliferation and angiogenesis capacity, forming vessel-like structures, reinforcing the association of HF recovery with angiogenic reprogramming. Mechanistically, knockdown of c-Myc by siRNA shifted post-LVAD nonmyocytes to a pre-LVAD-like state, while c-Myc overexpression by mRNA in pre-LVAD cells induced a post-LVAD-like phenotype, implicating c-Myc as 1 contributor to this fate switch. A model of HF recovery in mice mimicked the histological and functional changes in patients, with physiological evidence of increased microvascular perfusion, associated with a fibroblast-to-endothelial transition, documented by lineage tracing.

Conclusions: HF recovery involves reduced fibrosis and enhanced microvascularization, partly driven by fibroblast-to-endothelial cell fate transition. c-Myc functions as 1 regulator of this transition, offering a mechanistic entry point to develop regenerative therapies in HF.

Background: Survival after Fontan palliation for single ventricle heart disease has improved substantially, yet the long-term trajectory remains poorly defined. The Fontan Outcomes Network, a learning health network of 38 congenital heart centers in the United States and Canada, was established to address this gap. We report baseline characteristics and early findings from the first 1121 participants enrolled in this prospective clinical registry.

Methods: We performed a cross-sectional analysis of individuals who had undergone Fontan palliation enrolled in the Fontan Outcomes Network from August 2022 through August 2024. Demographic, clinical, imaging, procedural, and medication data were analyzed descriptively, overall and by age group (<12, 12 to <18, and ≥18 years).

Results: A total of 1121 participants were enrolled (mean age, 16.3±10.2 years; 471 [42%] female). Hypoplastic left heart syndrome (n=431 [38.5%]) and right ventricular-dominant anatomy (n=615 [54.9%]) were the most common primary cardiac diagnoses, especially in younger age groups. Extracardiac conduit was the most frequent Fontan type (n=749 [66.8%]). Typical Fontan-related adverse events were noted in 59% of cases (n=662), including chylous pleural effusions (n=108 [9.6%]), Fontan thrombosis (n=79 [7.1%]), and nonperioperative stroke (n=73 [6.5%]). A history of arrhythmia was present in 41.3% of patients (n=463) overall, increasing with age. Acquired comorbidities were present in 57.5% of patients (n=645), including asthma (n=132 [12%]) and sleep apnea (n=103 [9%]), with burden increasing by age. Antithrombotic medication use was nearly universal. Use of other medications varied widely by age, and included β-blockers, angiotensin-converting enzyme inhibitors, and pulmonary vasodilators. A clinical diagnosis of an anxiety disorder was present in 34.1% of patients (n=382), including 48.1% of adults (n=194 of 403), and antidepressants were prescribed in 11.8% of patients (n=132), including 23.6% of adults (n=95 of 403), highlighting the mental health needs of this population.

Conclusions: The Fontan Outcomes Network includes one of the largest prospective, multi-institutional data sets of patients with Fontan circulation. These initial findings demonstrate the potential for a collaborative learning health network to advance research and quality improvement for this rare disease population.

Background: Tissue-specific regulatory T cells (Tregs) accumulate in the heart after myocardial infarction (MI) and play a vital role in limiting inflammation and promoting tissue repair. However, the developmental trajectory of heart Tregs and the molecular cues that guide their recruitment to the heart remain poorly understood, impeding therapeutic strategies that leverage Treg-mediated cardiac protection.

Methods: We used single-cell and bulk RNA sequencing in a murine MI model to delineate the differentiation trajectory of Tregs from mediastinal lymph nodes to the heart. Functional validation was performed using Treg-specific Ccr8 (CC motif chemokine receptor 8) knockout mice (Ccr8^flox/floxFoxp3^Cre), Ccl1 (CC motif chemokine ligand 1) knockout mice (Ccl1^-/-), macrophage-targeted Ccl1 knockdown mice, Ccl1-overexpressing mice, and DEREG mice. The CCL1-CCR8 axis was evaluated in cardiac tissues and circulating blood from patients with MI.

Results: Single-cell RNA sequencing revealed a stepwise differentiation of mediastinal lymph node-derived naive Tregs into heart Tregs, marked by the progressive acquisition of CCR8 expression and reparative capacity. CCR8⁺ Tregs in the heart exhibited enhanced immunosuppressive and tissue-repair signatures. Treg-specific Ccr8 deletion led to reduced Treg accumulation and worsened cardiac function after MI, along with increased proinflammatory macrophage features and number of CD8⁺ T cells and natural killer cells. In addition, Tregs promoted a shift of macrophages toward an anti-inflammatory phenotype by secreting IL-1R2 (interleukin 1 receptor, type 2). We identified cardiac macrophages as the main source of CCL1, which was essential for CCR8⁺ Treg recruitment. Ccl1 deficiency or macrophage-specific Ccl1 knockdown impaired Treg infiltration and aggravated ventricular remodeling; Ccl1 overexpression promoted Treg recruitment and improved cardiac outcomes. Moreover, the cardioprotective effects of CCL1 were abolished in DEREG mice upon Treg depletion and Ccr8^flox/floxFoxp3^Cre mice, establishing a CCR8⁺ Treg-dependent mechanism. Furthermore, circulating CCR8⁺ Tregs and cardiac CCL1 were elevated in humans with MI, and the presence of CCR8⁺ Tregs and CCL1-expressing macrophages was confirmed in the hearts of patients with MI, suggesting important clinical relevance.

Conclusions: Our findings reveal a 2-phase Treg specialization process and establish the CCL1-CCR8 axis as a crucial pathway for Treg recruitment and function in the infarcted heart. Therapeutic targeting of this axis may improve immune-regulated cardiac repair after MI.

Aim: The "2026 AHA/ACC/ACCP/ACEP/CHEST/SCAI/SHM/SIR/SVM/SVN Guideline for the Evaluation and Management of Acute Pulmonary Embolism in Adults" is a de novo guideline that provides comprehensive recommendations for the evaluation, management, and follow-up of adult patients (≥18 years of age) with acute pulmonary embolism (PE). A key feature of this guideline is the introduction of the AHA/ACC Acute Pulmonary Embolism Clinical Categories, which enhance the precision of severity classification, prognosis assessment, and evidence-based therapeutic decision-making.

Methods: A comprehensive literature search was conducted from February 2024 to October 2024 to identify clinical studies, reviews, and other evidence conducted on human subjects that were published in English from MEDLINE (through PubMed), EMBASE, the Cochrane Library, Agency for Healthcare Research and Quality, and other selected databases relevant to this guideline. Select key studies published until April 2025 were added by the guideline writing committee as appropriate.

Structure: The focus of this clinical practice guideline is an evidence-based and patient-centered approach for acute PE evaluation and management of the adult patient. This guideline encompasses the period from the onset of symptoms through clinical follow-up, focusing on risk outcomes assessment, clinical diagnosis of acute PE, appropriate use of adjunctive cardiovascular testing, and management in both the acute and early post-acute phases of PE. It addresses evidence-based diagnostic and management strategies (including pharmacological therapies, advanced interventional therapies, and in-hospital support) for acute PE and associated outcomes.

Background: Limited data are available regarding the relative rates, etiology, and long-term prognostic implications of spontaneous myocardial infarction (MI) after percutaneous coronary intervention (PCI) versus coronary artery bypass graft (CABG) surgery for left main coronary artery disease (LMCAD).

Methods: MIs after PCI and CABG for LMCAD were adjudicated from the EXCEL trial (Evaluation of Xience Versus Coronary Artery Bypass Surgery for Effectiveness of Left Main Revascularization). Cox proportional hazards regression was performed to assess the association between spontaneous (and procedural) MI and cardiovascular and all-cause mortality at 5 years.

Results: Among 1882 patients who underwent LMCAD revascularization, spontaneous MI during 5-year follow-up occurred in 60 (6.8%) patients after PCI and in 29 (3.4%) patients after CABG (adjusted hazard ratio [adjHR], 2.01; 95 CI, 1.29-3.15; P=0.002). By multivariable analysis, spontaneous MI (as a time-adjusted covariate) was a strong independent predictor of subsequent cardiovascular mortality (adjHR, 9.39; 95% CI, 5.22-16.87) and all-cause mortality (adjHR, 4.77; 95% CI, 2.92-7.80) within 5 years, with consistent effects after PCI and CABG (P_interaction=0.60 and 0.78, respectively). In the same models, procedural MI as defined by extensive myonecrosis was associated with 5-year cardiovascular (adjHR, 3.02; 95% CI, 1.64-5.56) and all-cause mortality (adjHR, 2.38; 95% CI, 1.48-3.80), with consistent effects after PCI and CABG (P_interaction=0.23 and 0.34, respectively).

Conclusions: In the EXCEL trial, spontaneous MI occurred relatively infrequently within 5 years after LMCAD revascularization but at a higher rate after PCI compared with CABG. Spontaneous MI after revascularization was strongly related to subsequent cardiovascular and all-cause mortality, consistently after PCI and CABG, and was more strongly associated with mortality than was large procedural MI.

Registration: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT01205776.