Effects of Beta‐Blockers on Thermal and Cardiovascular Strain of Adults With Coronary Artery Disease During Extreme Heat Events
Bibliographic record
Abstract
Introduction Extreme heat is associated with a greater risk of adverse cardiovascular events, especially in people with cardiovascular disease. Many patients with cardiovascular disease are prescribed beta‐blockers. Some research suggests that in young healthy adults, cardio‐selective beta‐blockers may alter heat loss capacity. However, the effects of beta‐blockers on temperature regulation in older adults during an extreme heat event are unknown. The objective of this study was to compare thermal and cardiovascular responses during simulated extreme heat events between older adults with coronary artery disease (CAD) who use and do not use beta‐blockers. It was hypothesised that the increase in heart rate and skin blood flow would be smaller in CAD patients who use beta‐blockers compared to those who do not use beta‐blockers. Method 25 older adults (23 males/2 females) with stable CAD, 18 taking cardio‐selective beta‐blockers (BB: 66±8 y; 85.7±13.3 kg; 28.0±4.6 kg/m 2 ) and 7 not taking beta‐blockers (NBB: 66±7 y; 77.1±14.6 kg; 26.1±3.9 kg/m 2 ), were exposed to two 3‐hour simulated extreme heat events; one hot and humid (38°C, 60% relative humidity) and one hot and dry (45°C, 10% relative humidity). Rectal and mean skin temperatures, heart rate, and skin blood flow were continuously recorded. Whole body sweat losses were calculated from changes in nude body weight. Results At the end of the 3‐h hot and humid heat exposure, relative to pre‐exposure baseline the change in heart rate (BB: +7±5 bpm; NBB: +11±9 bpm, p=0.20), rectal (BB: +0.57±0.27°C; NBB: +0.60±0.31°C, p=0.76) and mean skin (BB: +5.1±1.2°C; NBB: +5.1±1.1°C, P=0.91) temperatures, and whole body sweat losses (BB: 771±480 g; NBB: 798±172 g, p=0.88) did not differ between groups. The change in skin blood flow from baseline was greater in the NBB (+32±23 arbitrary units) compared to the BB (+9±7 arbitrary units; p=0.01) group. At the end of the 3‐h hot and dry heat exposure, the increase in heart rate (BB: +9±8 bpm; NBB: +9±5 bpm, p=0.93), rectal (BB: +0.61±0.40°C; NBB: +0.62±0.22°C, p=0.91) and mean skin (BB: +5.9±0.9°C; NBB: +5.7±1.3°C; p=0.79) temperatures, whole body sweat losses (BB: 1252±174 g; NBB: 1207±169, p=0.56) and skin blood flow (BB: +26±22 arbitrary units; NBB: +26±39 arbitrary units; p=0.98) from baseline did not differ between groups. Conclusion Our preliminary evidence indicates that cardio‐selective beta‐blocker use does not alter thermal or cardiovascular strain in adults with stable coronary artery disease during simulated hot and humid or hot and dry extreme heat events.
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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) | 0.001 | 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".