Effect of ivabradine in heart failure: a meta-analysis of heart failure patients with reduced versus preserved ejection fraction

In clinical trials of heart failure reduced ejection fraction (HFrEF), ivabradine seemed to be an effective heart rate lowering agent associated with lower risk of cardiovascular death. In contrast, ivabradine failed to improve cardiovascular outcomes in heart failure preserved ejection fraction (HFpEF) despite the significant effect on heart rate. This meta-analysis is the first to compare the effects of ivabradine on heart rate and mortality parameters in HFpEF versus HFrEF. We screened three databases: PubMed, Embase, and Cochrane Library. The outcomes of these studies were mortality, reduction in heart rate, and left ventricular function improvement. We compared the efficacy of ivabradine treatment in HFpEF versus HFrEF. Heart rate analysis of pooled data showed decrease in both HFrEF (-17.646 beats/min) and HFpEF (-11.434 beats/min), and a tendency to have stronger bradycardic effect in HFrEF (p = 0.094) in randomized clinical trials. Left ventricular ejection fraction analysis revealed significant improvement in HFrEF (5.936, 95% CI: [4.199-7.672], p < 0.001) when compared with placebo (p < 0.001). We found that ivabradine significantly improves left ventricular performance in HFrEF, at the same time it exerts a tendency to have improved bradycardic effect in HFrEF. These disparate effects of ivabradine and the higher prevalence of non-cardiac comorbidities in HFpEF may explain the observed beneficial effects in HFrEF and the unchanged outcomes in HFpEF patients after ivabradine treatment.

Twenty-one days of spirulina supplementation lowers heart rate during submaximal cycling and augments power output during repeated sprints in trained cyclists

Spirulina supplementation has been reported to improve time to exhaustion and maximal oxygen consumption (V̇O2max). However, there is limited information on its influence over the multiple intensities experienced by cyclists during training and competition. Fifteen trained males (age 40 ± 8 years, V̇O2max 51.14 ± 6.43 mL/min/kg) ingested 6 g/day of spirulina or placebo for 21 days in a double-blinded randomised crossover design, with a 14-day washout period between trials. Participants completed a 1-hour submaximal endurance test at 55% external power output max and a 16.1-km time trial (day 1), followed by a lactate threshold test and repeated sprint performance tests (RSPTs) (day 2). Heart rate (bpm), respiratory exchange ratio, oxygen consumption (mL/min/kg), lactate and glucose (mmol/L), time (seconds), power output (W), and hemoglobin (g/L) were compared across conditions. Following spirulina supplementation, lactate and heart rate were significantly lower (P < 0.05) during submaximal endurance tests (2.05 ± 0.80 mmol/L vs 2.39 ± 0.89 mmol/L and 139 ± 11 bpm vs 144 ± 12 bpm), hemoglobin was significantly higher (152.6 ± 9.0 g/L) than placebo (143.2 ± 8.5 g/L), and peak and average power were significantly higher during RSPTs (968 ± 177 W vs 929 ± 149 W and 770 ± 117 W vs 738 ± 86 W). No differences existed between conditions for all oxygen consumption values, 16.1-km time trial measures, and lactate threshold tests (P > 0.05). Spirulina supplementation reduces homeostatic disturbances during submaximal exercise and augments power output during RSPTs. Novelty: Spirulina supplementation lowers heart rate and blood lactate during ∼1-hour submaximal cycling. Spirulina supplementation elicits significant augmentations in hemoglobin and power outputs during RSPTs.

The impact of face masks on performance and physiological outcomes during exercise: a systematic review and meta-analysis

Face masks are promoted for preventing spread of viruses; however, wearing a mask during exercise might increase CO₂ rebreathing, decrease arterial oxygenation, and decrease exercise performance. A systematic review and meta-analysis was conducted on the impact of wearing a mask during exercise. Data sources included SPORTDiscus, PubMed, and Medline. Eligibility criteria included all study designs comparing surgical, N95, or cloth masks to a no mask condition during any type of exercise where exercise performance and/or physiological parameters were evaluated. Healthy and clinical participants were included. Mean differences (MD) or standardized mean differences (SMD) with 95% confidence intervals were calculated and pooled effects assessed. Twenty-two studies involving 1573 participants (620 females, 953 males) were included. Surgical, or N95 masks did not impact exercise performance (SMD -0.05 [-0.16, 0.07] and -0.16 [-0.54, 0.22], respectively) but increased ratings of perceived exertion (SMD 0.33 [0.09, 0.58] and 0.61 [0.23, 0.99]) and dyspnea (SMD 0.6 [0.3, 0.9] for all masks). End-tidal CO₂ (MD 3.3 [1.0, 5.6] and 3.7 [3.0, 4.4] mm Hg), and heart rate (MD 2 [0,4] beats/min with N95 masks) slightly increased. Face masks can be worn during exercise with no influences on performance and minimal impacts on physiological variables. PROSPERO registration: CRD42020224988. Novelty: Face masks can be worn during exercise with no impacts on performance and minimal impacts on physiological variables.

Cardiorespiratory demands of competitive rock climbing

Rock climbing has become a mainstream sport, contested on the Olympic stage. The work/rest pattern of bouldering is unique among disciplines, and little is known about its physiological demands. This study characterised the cardiorespiratory responses to simulated competition. Eleven elite boulderers (7 male) volunteered to participate (age = 23.3 ± 4.5 years; mass = 68.2 ± 9.7 kg; stature = 1.73 ± 0.06 m; body fat = 10.4% ± 5%). Subjects completed incremental treadmill running to determine maximal capacities. On a separate day, they undertook a simulated Olympic-style climbing competition comprising 5 boulder problems, each separated by 5 min of rest. Pulmonary ventilation, gas exchange, and heart rate were assessed throughout. Total climbing time was 18.9 ± 2.7 min. Bouldering elicited a peak oxygen uptake of 35.8 ± 7.3 mL·kg^-1·min^-1 (∼75% of treadmill maximum) and a peak heart rate of 162 ± 14 beats·min^-1 (∼88% of maximum). Subjects spent 22.9% ± 8.6% of climbing time above the gas exchange threshold. At exercise cessation, there was an abrupt and significant increase in tidal volume (1.4 ± 0.4 vs. 1.8 ± 0.4 L; p = 0.006, d = 0.83) despite unchanged minute ventilation. Cardiorespiratory parameters returned to baseline within 4 min of the rest period. In conclusion, competitive bouldering elicits substantial cardiorespiratory demand and evidence of tidal volume constraint. Further studies are warranted to explore the effect of cardiorespiratory training on climbing performance. Novelty: Competitive bouldering evokes a high fraction of maximal oxygen uptake and prolonged periods above the gas exchange threshold. Climbing appears to impose a constraint on tidal volume expansion. Cardiorespiratory indices in elite climbers return to baseline within 2-4 min.

Prognostic value of heart rate reserve is additive to coronary flow velocity reserve during dipyridamole stress echocardiography

BACKGROUND

During dipyridamole stress echocardiography (SE), a blunted heart rate reserve (HRR) is a prognostically unfavourable sign of cardiac autonomic dysfunction.

AIM

To assess the prognostic meaning of HRR and coronary flow velocity reserve (CFVR).

METHODS

The study group comprised 2149 patients (1236 men; mean age 66±12 years) with suspected (n=1280) or known (n=869) coronary artery disease and without inducible regional wall motion abnormalities (RWMA) during dipyridamole SE (0.84mg/kg in 6min). We assessed CFVR of the left anterior descending artery with pulsed-wave Doppler as the ratio between hyperaemic peak and basal peak diastolic flow velocities (abnormal value≤2.0). HRR was calculated as the peak/resting ratio of heart rate from a 12-lead electrocardiogram (abnormal value≤1.22). All patients were followed up.

RESULTS

CFVR and HRR were abnormal in 520 (24%) and 670 (31%) patients, respectively. There was a positive linear correlation between CFVR and HRR (r=0.30; P<0.0001). During a median follow-up of 22 months (1st quartile 12 months, 3rd quartile 35 months), 75 (6%) patients died. The annual mortality was 1.6% in the overall population, 0.5% in the 1224 (57%) patients with normal CFVR and HRR, 1.7% in the 405 (19%) patients with abnormal HRR only, 3.6% in the 255 (12%) patients with abnormal CFVR only, and 6.2% in the 265 (12%) patients with abnormal CFVR and HRR.

CONCLUSIONS

HRR is weakly related to CFVR, and a blunted HRR usefully complements RWMA and CFVR for prediction of outcome with dipyridamole SE. The patient without inducible RWMA is still at intermediate risk, but the risk is low with concomitant preserved CFVR, and very low with concomitant normal HRR.

Vitamin D3 supplementation ameliorates ovariectomy-induced cardiac apoptotic and structural changes in adult albino rats

The effect of vitamin D on cardiac dysfunction after menopause is still under investigation. Therefore, we investigated the effect of vitamin D3 on cardiac apoptotic and structural changes in ovariectomized rats. Forty adult female albino rats were divided into 4 equal groups: sham rats, sham rats treated with vitamin D3, ovariectomized rats, and ovariectomized rats treated with vitamin D3 (500 IU/kg per day for 6 weeks, orally). Body mass, blood pressure, heart rate, and whole heart mass (WHM) were measured. Serum soluble receptors of advanced glycation end products (sRAGE), C-reactive protein, malondialdehyde, and total antioxidant capacity were estimated. Cardiac sections were stained with haematoxylin-eosin and Masson's trichrome stain. Fas and FasL apoptosis-related proteins were detected by immunohistochemistry. Vitamin D3 treatment significantly decreased ovariectomy-induced cardiac Fas and FasL apoptosis-related proteins, whole heart mass, body mass, C-reactive protein, and malondialdehyde accompanied by decreased inflammation and reduced collagen deposition between cardiac muscle fibres. However, vitamin D3 significantly increased total antioxidant capacity and sRAGE in ovariectomized and sham treated groups. Our findings suggest that vitamin D3 treatment can prevent ovariectomy-induced cardiac structural and apoptotic changes in rats via increasing sRAGE and antioxidant activity. Our results suggest that vitamin D3 has therapeutic effect against postmenopausal cardiovascular disease.

[Acute Effects on TH4 Thoracic Spine Mobilisation Techniques on the Sympathetic Nervous System - a Cross-Over Feasibility Study]

Acute Effects on TH4 Thoracic Spine Mobilisation Techniques on the Sympathetic Nervous System - a Cross-Over Feasibility Study Abstract. Up to date, empiric evidence about effects of thoracic spine mobilisation (TH4) on the sympathetic nervous system is lacking. The primary goal of this feasibility study was to determine adherence rate, side effects and the protocol as well as the implementation of the study design. The secondary goal was to analyse and interpret acute effects on the sympathetic nervous system after thoracic mobilisation in anterior thrust and posterior thrust on six healthy participants on two following days. The feasibility of this study was adequate. The spine mobilisations did not produce any adverse effects. The anterior thrust spine mobilisations showed a tendency in reducing the heart rate activity.

[Analysing heart rate variability to improve the monitoring of pain]

An innovative technique based on the analysis of instantaneous heart rate variability helps to improve the prevention and management of pain and discomfort. Simple to implement, this non-invasive technique is based on the continuous recording of the electrocardiograph signal.

Comparison between parameters from maximal cycle ergometer test first without respiratory gas analysis and thereafter with respiratory gas analysis among healthy prepubertal children

It is important to distinguish true and clinically relevant changes and methodological noise from measure to measure. In the clinical practice, maximal cycle ergometer tests are typically performed first without respiratory gas analysis and thereafter, if needed, with respiratory gas analysis. Therefore, we report a comparison of parameters from maximal cycle ergometer exercise tests that were done first without respiratory gas analysis and thereafter with it in 38 prepubertal and healthy children (20 girls, 18 boys). The Bland-Altman method was used to assess agreement in maximal workload (WMAX), heart rate (HR), and systolic blood pressure (SBP) between rest and maximum. Girls achieved higher WMAX in the exercise tests with respiratory gas analysis compared with exercise tests without respiratory gas analysis (p = 0.016), whereas WMAX was similar in the tests among boys. Maximal HR (proportional offset, -1%; coefficients of variation, 3.3%) and highest SBP (proportional offset, 3%; coefficients of variation, 10.6%) were similar in the tests among children. Precision and agreement for HR improved and precision for SBP worsened with increasing exercise intensity. Heteroscedasticity was not observed for WMAX, HR, or SBP. We conclude that maximal cycle ergometer tests without and with respiratory gas analysis can be used consecutively because measurement of respiratory gases did not impair performance or have a significant effect on the maximality of the exercise tests. Our results suggest that similar references can be used for children who accept or refuse using a mask during a maximal exercise test.

Endogenous adenosine release is involved in the control of heart rate in rats

Intravenous (i.v.) injections of adenosine exert marked effects on heart rate (HR) and arterial blood pressure (BP), but the role of an endogenous adenosine release by vagal stimulation has not been evaluated. In anaesthetized rats, we examined HR and BP changes induced by 1 min electrical vagal stimulation in the control condition, and then after i.v. injections of (i) atropine, (ii) propranolol, (iii) caffeine, (iv) 8 cyclopentyl-1,3-dipropylxanthine (DPCPX), or (v) dipyridamole to increase the plasma concentration of adenosine (APC). APC was measured by chromatography in the arterial blood before and at the end of vagal stimulation. The decrease in HR in the controls during vagal stimulation was markedly attenuated, but persisted after i.v. injections of atropine and propranolol. When first administered, DPCPX modestly but significantly reduced the HR response to vagal stimulation, but this disappeared after i.v. caffeine administration. Both the HR and BP responses were significantly accentuated after i.v. injection of dipyridamole. Vagal stimulation induced a significant increase in APC, proportional to the magnitude of HR decrease. Our data suggest that the inhibitory effects of electrical vagal stimulations on HR and BP were partly mediated through the activation of A1 and A2 receptors by an endogenous adenosine release. Our experimental data could help to understand the effects of ischemic preconditioning, which are partially mediated by adenosine.