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Aims: Atrial fibrillation (AF) may exacerbate exercise intolerance and haemodynamic limitations in individuals with heart failure (HF). Therefore, we performed a systematic search and meta-analysis to quantify the impact of AF on exercise tolerance (peak oxygen uptake, VO 2 peak; primary outcome) and exercise haemodynamics (secondary outcomes) in patients with HF., Methods and Results: PubMed, Scopus, and Web of Science databases were systematically searched for articles from inception to June 2024. Studies were included if they: (i) examined participants with HF; (ii) compared participants with AF to those not in AF (i.e. sinus rhythm); (iii) measured VO 2 peak from expired gas analysis. A fixed effects meta-analysis was performed, with groups compared using the weighted average effect size, represented as the weighted mean difference (WMD) with 95% confidence intervals (95% CI). Of 573 identified studies, 16 met the full inclusion comparing VO 2 peak in HF-patients in AF [HF-AF; n = 1,271, 68% male, 67 years, left ventricular ejection fraction (LVEF): 41%], and HF in sinus rhythm (HF-SR; n = 4910; 62% male, 62 years, LVEF: 41%). VO 2 peak was significantly lower in HF-AF (WMD: -1.55mL/kg/min, 95%-CI: -1.81 to -1.28, n = 6471). This coincided with a slightly lower peak heart rate (WMD: -2.94 b/min, 95%-CI: -4.76 to -1.13 b/min, n = 5115), decreased O 2 pulse (WMD: -1.58 mL/beat, 95% CI: -1.90 to -1.26, n = 3049), and lower systolic blood pressure (WMD: -11.11 mmHg, 95% CI: -14.01 to -8.21, n = 2409)., Conclusion: In patients with HF, AF is associated with greater VO 2 peak impairment, potentially due to reduced stroke volume and/or arterio-venous oxygen difference. This highlights the importance of combined strategies to identify and manage AF in individuals with HF., Competing Interests: Conflict of interest: None declared., (© The Author(s) 2025. Published by Oxford University Press on behalf of the European Society of Cardiology.)

Background: Hematopoietic stem cell transplantation (HSCT) is a common therapy for many hematologic malignancies. While advances in transplant practice have improved cancer-specific outcomes, multiple and debilitating long term physical and psychologic effects remain. Patients undergoing allogeneic bone marrow transplantation (allo-BMT) are often critically ill at initial diagnosis and with necessary sequential treatments become increasingly frail and deconditioned. Despite modern treatment regimens and support, cardiovascular disease remains a leading cause of non-relapse mortality among allo-BMT survivors. Well-established multi-disciplinary care models such as cardiac rehabilitation offer holistic care including exercise training, nursing support, physical/occupational therapy, psychosocial support and nutritional education. HSCT patients may be excluded from conventional outpatient physical rehabilitation programs due to prolonged pancytopenia and frequent hospital admissions. In Canada, dedicated cancer-specific rehabilitation programs are available only at major tertiary academic centers., Methods: The primary aim of this study will evaluate the feasibility and acceptability of a multimodal care navigation (nursing, exercise, nutrition) intervention with content delivery facilitated by a supportive care web-based 'app' extending from diagnosis to 1 year in the allogeneic bone marrow transplant population. Adult patients scheduled for allo-BMT will receive support from exercise specialist, nursing support and dietician expertise alongside a supportive care 'app' with additional in-person or virtual cardiac rehabilitation support., Discussion: To our knowledge, no research team is taking such a holistic, multidisciplinary approach to address the debilitating physiologic and psychological consequences of allo-BMT. We expect the findings to inform the optimal timing and patient preferences to develop studies examining risk-specific, individualized interventions (including exercise, pharmacotherapy, combination treatments) to reduce or prevent symptoms and dysfunction. We expect this innovative program to identify ways to benefit innumerable patients with hematologic and other malignancies. Ultimately, we hope to transform supportive care in hematopoietic stem cell transplantation., Trial Registration: Clinicaltrials.gov ID: NCT05579678., Competing Interests: Declarations. Ethics approval and consent to participate: This study was reviewed and approved by the Health Research Ethics Board of Alberta (HREBA) – Cancer Committee, Ethics ID#: HREBA.CC-22-0164. Written informed consent is provided by all study participants. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests., (© 2025. The Author(s).)

Recent evidence suggests that ketone bodies have therapeutic potential in many cardiovascular diseases including heart failure (HF). Accordingly, this has led to multiple clinical trials that use ketone esters to treat HF patients, which we term ketone therapy. Ketone esters, specifically ketone monoesters, are synthetic compounds which, when consumed, are de-esterified into two β-hydroxybutyrate (βOHB) molecules and increase the circulating βOHB concentration. While many studies have primarily focused on the cardiac benefits of ketone therapy in HF, ketones can have numerous favorable effects in other organs such as the vasculature and skeletal muscle. Importantly, vascular and skeletal muscle dysfunction are also heavily implicated in the reduced exercise tolerance, the hallmark feature in HF with reduced (HFrEF) and preserved (HFpEF) ejection fraction, suggesting that some of the benefits observed in HF in response to ketone therapy may involve these non-cardiac pathways. Thus, we review the evidence suggesting how ketone therapy may be beneficial in improving cardiovascular and skeletal muscle function in HF and identify various potential mechanisms that may be important in the beneficial non-cardiac effects of ketones in HF., (© The Author(s) 2025. Published by Oxford University Press on behalf of the European Society of Cardiology.)