Unraveling Heart Failure Phenotypes: A Systematic Review and Meta-analysis of Peak Oxygen Uptake and Its Determinants
Bibliographic record
Abstract
<h2>Abstract</h2><h3>Background</h3> Understanding the impact of heart failure (HF) phenotype on peak oxygen uptake (peak <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mrow></mml:math>O<sub>2</sub>) is essential for advancing personalized treatment strategies and enhancing patient outcomes. Therefore, we conducted a systematic review and meta-analysis of the evidence examining differences in peak <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mrow></mml:math>O<sub>2</sub> (primary objective) and its determinants (secondary objectives) between patients with HF with reduced (HFrEF) or preserved ejection fraction (HFpEF). <h3>Methods</h3> Studies comparing peak <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mrow></mml:math>O<sub>2</sub> in HFrEF vs HFpEF were found through PubMed (1967-2024), Scopus (1981-2024), and Web of Science (1985-2024). Data extraction and methodologic quality assessment were completed by 2 independent coders. Differences between HFrEF and HFpEF were compared using weighted mean difference (WMD) and 95% confidence intervals (95% CIs) derived from random effects meta-analysis. <h3>Results</h3> After screening 3107 articles, 25 unique studies were included in the analysis for the primary outcome (HFrEF n = 3783; HFpEF n = 3279). Peak <mml:math><mml:mrow><mml:mi>V</mml:mi><mml:mo>˙</mml:mo></mml:mrow></mml:math>O<sub>2</sub> (WMD: –1.6 mL/kg/min, 95% CI: –2.3 to –0.8 mL/kg/min), and peak exercise measures of cardiac output (WMD: –1.1 L/min, 95% CI: –2.1 to –0.2 L/min), stroke volume (WMD: –10.1 mL, 95% CI: –16.6 to –3.7 mL), heart rate (WMD: –4 bpm, 95% CI: –6 to –2 bpm), and left ventricular ejection fraction (WMD: –28.2%, 95% CI: –32.6% to –23.8%) were significantly lower while peak exercise arterial-venous oxygen difference was significantly higher in HFrEF compared with HFpEF (2.3 mL/dL, 95% CI: 1.6-2.9 mL/dL). <h3>Conclusions</h3> Our findings highlight distinct physiological impairments along the oxygen cascade in HFrEF compared with HFpEF, with direct implications for the management and treatment strategies of these HF subtypes.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.017 | 0.003 |
| Bibliometrics | 0.000 | 0.001 |
| 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".