Abstract 4141300: Sympathetic Response to Dynamic Exercise Predicts the Exercise Capacity of Patients with Heart Failure with Preserved Ejection Fraction
Bibliographic record
Abstract
Background: In heart failure, sympathetic excess and exercise intolerance impair quality of life. In HFrEF, muscle sympathetic nerve activity (MSNA) is augmented at rest and in response to exercise, of which the latter relates inversely to peak oxygen uptake (VO 2peak ). Aims: To determine, in HFpEF: 1) if resting MSNA is elevated, independent of its accompanying comorbidities; and 2) if MSNA responses to exercise are also increased and relate inversely to exercise capacity. Methods: In 13 HFpEF patients (70±6 yrs; LVEF: 63±6%; NTproBNP: 658±610 pg/ml), 17 co-morbid controls (CMC; 67±8 yrs), matched for medication and presence of comorbidities, and 18 healthy controls (HC; 65±8 yrs), we measured, in the seated position, heart rate, blood pressure, and MSNA (microneurography) during: i) 7 min baseline; ii) 2 min isometric (IHG; 40% maximal voluntary contraction [MVC]) or rhythmic handgrip (RHG; 50% and 30% MVC) exercise, followed by 2 min post-HG ischemia (PHGI); and iii) 4 min 1-leg cycling (2 min each at mild and moderate intensity). VO 2peak was obtained by open circuit spirometry. Results: Resting MSNA was higher in HFpEF (48±14 bursts/min) vs. CMC (36±9 bursts/min; P=0.02) and HC (34±12 bursts/min; P<0.01). In HFpEF, relative VO 2peak (16±5 ml/kg/min) was lower vs. CMC (25±7 ml/kg/min; P=0.02) and HC (29±9 ml/kg/min; P<0.001). During HG, MSNA responses were similar in magnitude in all groups (P<0.05), resulting in higher absolute values in HFpEF vs. CMC and HC during HG and PHGI at 40% IHG (P<0.05) and HG only at 50% and 30% RHG (P<0.05). During cycling, MSNA decreased during mild (−4±4 bursts/min; P=0.01) and moderate (−8±6 bursts/min; P<0.001) cycling in HC, was unchanged during mild (+1±6 bursts/min; P=0.42) and moderate (+2±8 bursts/min; P=0.28) cycling in CMC, yet increased in HFpEF during both mild (+8±8 bursts/min; P<0.001) and moderate (+9±10 bursts/min; P<0.001) cycling. In HFpEF, the change in MSNA elicited by moderate cycling related inversely to relative VO 2peak (R 2 =0.51; P<0.01). No such relationship existed in either CMC or HC (P>0.05). Conclusion: In contrast to comorbidity-matched controls, HFpEF patients exhibit augmented MSNA at rest and during exercise. As with HFrEF, the magnitude of such ‘paradoxical’ sympathoexcitation during dynamic exercise related inversely to exercise capacity, observations consistent with the concept of a peripheral neurogenic, vasoconstrictor limit on exercise in all with heart failure, regardless of LVEF.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 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) | 0.004 | 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 source (direct Gemma or distilled Codex), 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".