Exercise capacity and hemodynamics in heart failure with preserved ejection fraction patients with and without atrial fibrillation
Bibliographic record
Abstract
Abstract Background Atrial fibrillation (AF) is a common comorbidity in individuals with heart failure with preserved ejection fraction (HFpEF) that contributes to increased morbidity and mortality. However, the impact of AF on key HFpEF physiologic features, including exercise tolerance (peak oxygen uptake, VO2peak) hemodynamic responses, and peripheral oxygen extraction remains unclear. Purpose To compare VO2peak, peak exercise hemodynamics and arterio-venous oxygen difference (a-vO2diff) in patients with HFpEF with or without AF. Methods The study cohort included patients referred to a multi-disciplinary unexplained dyspnea clinic with an established HFpEF diagnosis after detailed clinical and hemodynamic evaluation. Patients were sub-grouped based on whether they were in AF (HFpEF-AF; n=88) or sinus rhythm (HFpEF-SR; n=625) at the time of the evaluation. Peak VO2, exercise hemodynamics and a-vO2diff were assessed from maximal cardiopulmonary exercise testing with simultaneous echocardiography (CPETecho). AF and SR sub-groups were compared using ANCOVA with adjustment for age and sex. Results The HFpEF-AF group was slightly older (76±6yrs vs 73±8yrs, P<0.001), with similar (P>0.2 for all) body mass index (28.2±4.8kg/m2 vs 29.6±11.2kg/m2), resting left-ventricular (LV) ejection fraction (61±8 vs 62±8) and LV mass index (92±36g/m2 vs 93±25g/m2) but higher indexed left-atrial volume (47±15mL/m2 vs 32±13mL/m2, P<0.001) and median [interquartile range] NT-proBNP levels (1200ng/L [805, 1750] vs 290ng/L [140, 530], P<0.001). The HFpEF-AF group also had a higher proportion of males (42% vs 55%, P=0.023), but similar prevalence of hypertension (75% vs 79%, P=0.43) and diabetes (22% vs 22%, P=0.91). Both groups showed comparable peak effort during CPETecho (peak respiratory exchange ratio: HFpEF-AF=1.06±0.11 vs HFpEF-SR=1.07±0.12, P=0.25). Peak VO2 was 9% lower in HFpEF-AF (P=0.027), accompanied by a 10% reduction in peak cardiac output (P=0.007), despite a 12% higher heart rate (P<0.001). Stroke volume was 19% lower in HFpEF-AF, related to smaller left ventricular end-diastolic volume (12% lower, P=0.001), which decreased further during exercise (5% decrease vs. 3% increase in HFpEF-SR, interaction P<0.001). In contrast, the a-vO2diff was not different between groups (P=0.94). HFpEF-AF and HFpEF-SR also showed similar resting (17.8±4.1mmHg vs 17.2±4.1 mmHg, P=0.29) and peak exercise mean pulmonary artery pressures (mPAP; 32.2±6.6mmHg vs 32.7±7.0mmHg, P=0.48), but the mPAP-CO slope tended to be 14% higher in HFpEF-AF (Fig. 1, P=0.086). Conclusions Patients with HFpEF in AF have a lower peak oxygen uptake and reduced end-diastolic volume, stroke volume and cardiac output reserve compared to patients with HFpEF in sinus rhythm. These findings highlight differences in HFpEF exercise physiology associated with AF, suggesting a potential need for tailored therapeutic approaches to optimize their functional outcomes.Fig. 1Impact of AF on exercise responsesFig. 2Impact of AF on LV responses
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".