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Despite the wide effects of cardiorespiratory fitness (CRF) on metabolic, cardiovascular, pulmonary and neurological health, challenges in the feasibility and reproducibility of CRF measurements have impeded its use for clinical decision-making. Here we link proteomic profiles to CRF in 14,145 individuals across four international cohorts with diverse CRF ascertainment methods to establish, validate and characterize a proteomic CRF score. In a cohort of around 22,000 individuals in the UK Biobank, a proteomic CRF score was associated with a reduced risk of all-cause mortality (unadjusted hazard ratio 0.50 (95% confidence interval 0.48-0.52) per 1 s.d. increase). The proteomic CRF score was also associated with multisystem disease risk and provided risk reclassification and discrimination beyond clinical risk factors, as well as modulating high polygenic risk of certain diseases. Finally, we observed dynamicity of the proteomic CRF score in individuals who undertook a 20-week exercise training program and an association of the score with the degree of the effect of training on CRF, suggesting potential use of the score for personalization of exercise recommendations. These results indicate that population-based proteomics provides biologically relevant molecular readouts of CRF that are additive to genetic risk, potentially modifiable and clinically translatable.
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Aptidão Cardiorrespiratória , Proteômica , Humanos , Proteômica/métodos , Masculino , Feminino , Pessoa de Meia-Idade , Fatores de Risco , Adulto , Idoso , Estudos de Coortes , Exercício Físico/fisiologiaRESUMO
Background During exercise, a healthy arterial system facilitates increased blood flow and distributes it effectively to essential organs. Accordingly, we sought to understand how arterial stiffening might impair cardiorespiratory fitness in community-dwelling individuals. Methods and Results Arterial tonometry and maximum effort cardiopulmonary exercise testing were performed on Framingham Heart Study participants (N=2898, age 54±9 years, 53% women, body mass index 28.1±5.3 kg/m2). We related 5 arterial stiffness measures (carotid-femoral pulse wave velocity [CFPWV]: a measure of aortic wall stiffness; central pulse pressure, forward wave amplitude, characteristic impedance: measures of pressure pulsatility; and augmentation index: a measure of relative wave reflection) to multidimensional exercise responses using linear models adjusted for age, sex, resting heart rate, habitual physical activity, and clinical risk factors. Greater CFPWV, augmentation index, and characteristic impedance were associated with lower peak oxygen uptake (VO2; all P<0.0001). We observed consistency of associations of CFPWV with peak oxygen uptake across age, sex, and cardiovascular risk profile (interaction P>0.05). However, the CFPWV-peak oxygen uptake relation was attenuated in individuals with obesity (P=0.002 for obesity*CFPWV interaction). Higher CPFWV, augmentation index, and characteristic impedance were also related to cardiopulmonary exercise testing measures reflecting adverse O2 kinetics and lower stroke volume and peripheral O2 extraction but not to ventilatory efficiency, a prognostic measure of right ventricular-pulmonary vascular performance. Conclusions Our findings delineate relations of arterial stiffness and cardiorespiratory fitness in community-dwelling individuals. Future studies are warranted to evaluate whether the physiological measures implicated here may represent potential targets for improving cardiorespiratory fitness in the general population.
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Aptidão Cardiorrespiratória , Rigidez Vascular , Humanos , Feminino , Pessoa de Meia-Idade , Masculino , Rigidez Vascular/fisiologia , Análise de Onda de Pulso , Obesidade , OxigênioRESUMO
Treatment of circulatory shock in critically ill patients requires management of blood pressure using invasive monitoring, but uncertainty remains as to optimal individual blood pressure targets. Critical closing pressure, which refers to the arterial pressure when blood flow stops, can provide a fundamental measure of vascular tone in response to disease and therapy, but it has not previously been possible to measure this parameter routinely in clinical care. Here we describe a method to continuously measure critical closing pressure in the systemic circulation using readily available blood pressure monitors and then show that tissue perfusion pressure (TPP), defined as the difference between mean arterial pressure and critical closing pressure, provides unique information compared to other hemodynamic parameters. Using analyses of 5,988 admissions to a modern cardiac intensive care unit, and externally validated with 864 admissions to another institution, we show that TPP can predict the risk of mortality, length of hospital stay and peak blood lactate levels. These results indicate that TPP may provide an additional target for blood pressure optimization in patients with circulatory shock.
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Unidades de Terapia Intensiva , Choque , Humanos , Hemodinâmica , Pressão Sanguínea , PerfusãoRESUMO
Background Cardiorespiratory fitness is a powerful predictor of health outcomes that is currently underused in primary prevention, especially in young adults. We sought to develop a blood-based biomarker of cardiorespiratory fitness that is easily translatable across populations. Methods and Results Maximal effort cardiopulmonary exercise testing for quantification of cardiorespiratory fitness (by peak oxygen uptake) and profiling of >200 metabolites at rest were performed in the FHS (Framingham Heart Study; 2016-2019). A metabolomic fitness score was derived/validated in the FHS and was associated with long-term outcomes in the younger CARDIA (Coronary Artery Risk Development in Young Adults) study. In the FHS (derivation, N=451; validation, N=914; age 54±8 years, 53% women, body mass index 27.7±5.3 kg/m2), we used LASSO (least absolute shrinkage and selection operator) regression to develop a multimetabolite score to predict peak oxygen uptake (correlation with peak oxygen uptake r=0.77 in derivation, 0.61 in validation; both P<0.0001). In a linear model including clinical risk factors, a ≈1-SD higher metabolomic fitness score had equivalent magnitude of association with peak oxygen uptake as a 9.2-year age increment. In the CARDIA study (N=2300, median follow-up 26.9 years, age 32±4 years, 44% women, 44% Black individuals), a 1-SD higher metabolomic fitness score was associated with a 44% lower risk for mortality (hazard ratio [HR], 0.56 [95% CI, 0.47-0.68]; P<0.0001) and 32% lower risk for cardiovascular disease (HR, 0.68 [95% CI, 0.55-0.84]; P=0.0003) in models adjusted for age, sex, and race, which remained robust with adjustment for clinical risk factors. Conclusions A blood-based biomarker of cardiorespiratory fitness largely independent of traditional risk factors is associated with long-term risk of cardiovascular disease and mortality in young adults.
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Aptidão Cardiorrespiratória , Doenças Cardiovasculares , Adulto , Biomarcadores , Doenças Cardiovasculares/diagnóstico , Doenças Cardiovasculares/epidemiologia , Doenças Cardiovasculares/prevenção & controle , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Avaliação de Resultados em Cuidados de Saúde , Oxigênio , Aptidão Física , Fatores de Risco , Adulto JovemRESUMO
Acute and chronic animal models of exercise are commonly used in research. Acute exercise testing is used, often in combination with genetic, pharmacological, or other manipulations, to study the impact of these manipulations on the cardiovascular response to exercise and to detect impairments or improvements in cardiovascular function that may not be evident at rest. Chronic exercise conditioning models are used to study the cardiac phenotypic response to regular exercise training and as a platform for discovery of novel pathways mediating cardiovascular benefits conferred by exercise conditioning that could be exploited therapeutically. The cardiovascular benefits of exercise are well established, and, frequently, molecular manipulations that mimic the pathway changes induced by exercise recapitulate at least some of its benefits. This review discusses approaches for assessing cardiovascular function during an acute exercise challenge in rodents, as well as practical and conceptual considerations in the use of common rodent exercise conditioning models. The case for studying feeding in the Burmese python as a model for exercise-like physiological adaptation is also explored.
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Boidae , Condicionamento Físico Animal , Animais , Boidae/genética , Fenômenos Fisiológicos Cardiovasculares , Modelos Animais , Condicionamento Físico Animal/fisiologia , RoedoresRESUMO
Background: Postoperative delirium (POD) is an acute altered mental state commonly encountered after cardiac surgery. The pathophysiological mechanisms underlying POD remain unclear. We aimed to identify circulating proteins significantly altered after major cardiac surgery with cardiopulmonary bypass (CPB). We also aimed to enable inferences on associations with POD. Methods: Serum and whole blood samples were collected before CPB (n = 16 patients; n = 8 with POD) and again from the same patients on postoperative day 1. All patients were clinically evaluated for POD on postoperative days 1-3. An aptamer-based proteomics platform (SOMAscan) was used to quantify serum protein abundance in patients with POD compared with non-POD controls. We also performed a lipopolysaccharide (LPS)-based in vitro functional analysis (TruCulture) on whole blood samples from patients with POD and non-POD controls to approximate surgical stress. Cytokine levels were determined using a Luminex immunoassay. Results: Cardiac surgery with CPB resulted in a significant (padj < 0.01) change in 48.8% (637 out of 1,305) of proteins detected by SOMAscan. Gene set enrichment showed that the most impacted biological processes involved myeloid cell activation. Specifically, activation and degranulation of neutrophils were the top five highest-scoring processes. Pathway analyses with the Kyoto Encyclopedia of Genes and Genomes (KEGG) showed that metabolic enzymes, particularly those of glycolysis, were elevated in serum concentration after surgery. Several proteins were significantly increased postoperatively in patients diagnosed with POD relative to the non-POD controls, with interleukin-6 (IL-6) showing the greatest fold-change. LPS stimulation of whole blood samples confirmed these findings. Linear regression analysis showed a highly significant correlation between Confusion Assessment Method (CAM) scores and CPB-mediated changes in cGMP-inhibited 3',5'-cyclic phosphodiesterase A (PDE3A). Conclusions: Cardiac surgery with CPB resulted in inflammasome changes accompanied by unexpected increases in metabolic pathways. In exploratory analyses, we found that POD was associated with changes in the expression level of various proteins, most notably IL-6 and PDE3A. This study and ongoing protein biomarker studies will likely help quantify risk or confirm the diagnosis for POD and increase understanding of its pathophysiological mechanisms.
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AIMS: While greater physical activity (PA) is associated with improved health outcomes, the direct links between distinct components of PA, their changes over time, and cardiorespiratory fitness are incompletely understood. METHODS AND RESULTS: Maximum effort cardiopulmonary exercise testing (CPET) and objective PA measures [sedentary time (SED), steps/day, and moderate-vigorous PA (MVPA)] via accelerometers worn for 1 week concurrent with CPET and 7.8 years prior were obtained in 2070 Framingham Heart Study participants [age 54 ± 9 years, 51% women, SED 810 ± 83 min/day, steps/day 7737 ± 3520, MVPA 22.3 ± 20.3 min/day, peak oxygen uptake (VO2) 23.6 ± 6.9 mL/kg/min]. Adjusted for clinical risk factors, increases in steps/day and MVPA and reduced SED between the two assessments were associated with distinct aspects of cardiorespiratory fitness (measured by VO2) during initiation, early-moderate level, peak exercise, and recovery, with the highest effect estimates for MVPA (false discovery rate <5% for all). Findings were largely consistent across categories of age, sex, obesity, and cardiovascular risk. Increases of 17 min of MVPA/day [95% confidence interval (CI) 14-21] or 4312 steps/day (95% CI 3439-5781; ≈54 min at 80 steps/min), or reductions of 249 min of SED per day (95% CI 149-777) between the two exam cycles corresponded to a 5% (1.2 mL/kg/min) higher peak VO2. Individuals with high (above-mean) steps or MVPA demonstrated above average peak VO2 values regardless of whether they had high or low SED. CONCLUSIONS: Our findings provide a detailed assessment of relations of different types of PA with multidimensional cardiorespiratory fitness measures and suggest favourable longitudinal changes in PA (and MVPA in particular) are associated with greater objective fitness.
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Aptidão Cardiorrespiratória , Exercício Físico , Teste de Esforço , Feminino , Humanos , Estudos Longitudinais , Masculino , Pessoa de Meia-Idade , Aptidão Física , Comportamento SedentárioRESUMO
Cardiorespiratory fitness (CRF) is intricately related to health status. The optimal approach for CRF quantification is through assessment of peak oxygen uptake (VO2), but such measurements have been largely confined to small referral populations. Here we describe protocols and methodological considerations for peak VO2 assessment and determination of volitional effort in a large community-based sample. Maximum incremental ramp cycle ergometry cardiopulmonary exercise testing (CPET) was performed by Framingham Heart Study participants at a routine study visit (2016 to 2019). Of 3,486 individuals presenting for a multicomponent study visit, 3,116 (89%) completed CPET. The sample was middle-aged (54 ± 9 years), with 53% women, body mass index 28.3 ± 5.6 kg/m2, 48% with hypertension, 6% smokers, and 8% with diabetes. Exercise duration was 12.0 ± 2.1 minutes (limits 3.7to20.5). No major cardiovascular events occurred. A total of 98%, 96%, 90%, 76%, and 57% of the sample reached peak respiratory exchange ratio (RER) values of ≥1.0, ≥1.05, ≥1.10, ≥1.15, and ≥1.20, respectively (mean peak RER = 1.21 ± 0.10). With rising peak RER values up to ≈1.10, steep changes were observed for percent predicted peak VO2, VO2 at the ventilatory threshold/peak VO2, heart rate response, and Borg (subjective dyspnea) scores. More shallow changes for effort dependent CPET variables were observed with higher achieved RER values. In conclusion, measurement of peak VO2 is feasible and safe in a large sample of middle-aged, community-dwelling individuals with heterogeneous cardiovascular risk profiles. Peak RER ≥1.10 was achievable by the majority of middle-aged adults and RER values beyond this threshold did not necessarily correspond to higher peak VO2 values.
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Aptidão Cardiorrespiratória/fisiologia , Doenças Cardiovasculares/prevenção & controle , Exercício Físico/fisiologia , Nível de Saúde , Frequência Cardíaca/fisiologia , Doenças Cardiovasculares/fisiopatologia , Estudos de Viabilidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Consumo de Oxigênio/fisiologia , Estudos ProspectivosRESUMO
Importance: Heart failure with preserved ejection fraction (HFpEF) is a joint metabolic and cardiovascular disorder with significant noncardiac contributions. Objective: To define and quantify the metabolic cost of initiating exercise in individuals with and without HFpEF and its functional consequences. Design, Setting, and Participants: This prospective cohort study included individuals with hemodynamically confirmed HFpEF from the Massachusetts General Hospital Exercise Study (MGH-ExS) and community-dwelling participants from the Framingham Heart Study (FHS). Analysis began April 2016 and ended November 2020. Exposures: Internal work (IW), a measure of work equivalents required to initiate movement. Main Outcomes and Measures: Using breath-by-breath oxygen uptake (VÌo2) measurements and VÌo2-work rate associations, cost of initiating exercise (IW) in patients with HFpEF (MGH-ExS) and in community-dwelling individuals (FHS) was quantified. Linear regression was used to estimate associations between IW and clinical/hemodynamic measures. Results: Of 3231 patients, 184 (5.7%) had HFpEF and were from MGH-ExS, and 3047 (94.3%) were community-dwelling individuals from FHS. In the MGH-ExS cohort, 86 (47%) were women, the median (interquartile range) age was 63 (53-72) years, and the median (interquartile range) peak VÌo2 level was 13.33 (11.77-15.62) mL/kg/min. In the FHS cohort, 1620 (53%) were women, the median (interquartile range) age was 54 (48-60) years, and the median (interquartile range) peak VÌo2 level was 22.2 (17.85-27.35) mL/kg/min. IW was higher in patients with HFpEF and accounted for 27% (interquartile range, 21%-39%) of the total work (IW + measured external workload on the cycle), compared with 15% (interquartile range, 12%-20%) of that in FHS participants. Body mass index accounted for greatest explained variance in patients with HFpEF from MGH-ExS and FHS participants (22% and 18%, respectively), while resting cardiac output and biventricular filling pressures were not significantly associated with variance in IW in patients with HFpEF. A higher IW in patients with HFpEF was associated with a greater increase in left- and right-sided cardiac filing pressure during unloaded exercise, despite similar resting hemodynamic measures across IW. Conclusions and Relevance: This study found that internal work, a new body mass index-related measure reflecting the metabolic cost of initiating movement, is higher in individuals with HFpEF compared with middle-aged adults in the community and is associated with steep, early increases in cardiac filling pressures. These findings highlight the importance of quantifying heterogeneous responses to exercise initiation when evaluating functional intolerance in individuals at risk for or with HFpEF.
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Insuficiência Cardíaca/fisiopatologia , Consumo de Oxigênio/fisiologia , Idoso , Índice de Massa Corporal , Estudos de Coortes , Teste de Esforço , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Obesidade/fisiopatologiaRESUMO
BACKGROUND: Whereas regular exercise is associated with lower risk of cardiovascular disease and mortality, mechanisms of exercise-mediated health benefits remain less clear. We used metabolite profiling before and after acute exercise to delineate the metabolic architecture of exercise response patterns in humans. METHODS: Cardiopulmonary exercise testing and metabolite profiling was performed on Framingham Heart Study participants (age 53±8 years, 63% women) with blood drawn at rest (n=471) and at peak exercise (n=411). RESULTS: We observed changes in circulating levels for 502 of 588 measured metabolites from rest to peak exercise (exercise duration 11.9±2.1 minutes) at a 5% false discovery rate. Changes included reductions in metabolites implicated in insulin resistance (glutamate, -29%; P=1.5×10-55; dimethylguanidino valeric acid [DMGV], -18%; P=5.8×10-18) and increases in metabolites associated with lipolysis (1-methylnicotinamide, +33%; P=6.1×10-67), nitric oxide bioavailability (arginine/ornithine + citrulline, +29%; P=2.8×10-169), and adipose browning (12,13-dihydroxy-9Z-octadecenoic acid +26%; P=7.4×10-38), among other pathways relevant to cardiometabolic risk. We assayed 177 metabolites in a separate Framingham Heart Study replication sample (n=783, age 54±8 years, 51% women) and observed concordant changes in 164 metabolites (92.6%) at 5% false discovery rate. Exercise-induced metabolite changes were variably related to the amount of exercise performed (peak workload), sex, and body mass index. There was attenuation of favorable excursions in some metabolites in individuals with higher body mass index and greater excursions in select cardioprotective metabolites in women despite less exercise performed. Distinct preexercise metabolite levels were associated with different physiologic dimensions of fitness (eg, ventilatory efficiency, exercise blood pressure, peak Vo2). We identified 4 metabolite signatures of exercise response patterns that were then analyzed in a separate cohort (Framingham Offspring Study; n=2045, age 55±10 years, 51% women), 2 of which were associated with overall mortality over median follow-up of 23.1 years (P≤0.003 for both). CONCLUSIONS: In a large sample of community-dwelling individuals, acute exercise elicits widespread changes in the circulating metabolome. Metabolic changes identify pathways central to cardiometabolic health, cardiovascular disease, and long-term outcome. These findings provide a detailed map of the metabolic response to acute exercise in humans and identify potential mechanisms responsible for the beneficial cardiometabolic effects of exercise for future study.
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Índice de Massa Corporal , Doenças Cardiovasculares , Exercício Físico , Metaboloma , Metabolômica , Adulto , Idoso , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/fisiopatologia , Doenças Cardiovasculares/terapia , Feminino , Humanos , Masculino , Massachusetts , Pessoa de Meia-Idade , Estudos ProspectivosRESUMO
Routine endurance exercise confers numerous health benefits, and high intensity exercise may accelerate and magnify many of these benefits. To date, explanatory molecular mechanisms and the influence of exercise intensity remain poorly understood. Circulating factors are hypothesized to transduce some of the systemic effects of exercise. We sought to examine the role of exercise and exercise intensity on the human plasma proteome. We employed an aptamer-based method to examine 1,305 plasma proteins in 12 participants before and after exercise at two physiologically defined intensities (moderate and high) to determine the proteomic response. We demonstrate that the human plasma proteome is responsive to acute exercise in an intensity-dependent manner with enrichment analysis suggesting functional biological differences between the moderate and high intensity doses. Through integration of available genetic data, we estimate the effects of acute exercise on exercise-associated traits and find proteomic responses that may contribute to observed clinical effects on coronary artery disease and blood pressure regulation. In sum, we provide supportive evidence that moderate and high intensity exercise elicit different signaling responses, that exercise may act in part non-cell autonomously through circulating plasma proteins, and that plasma protein dynamics can simulate some the beneficial and adverse effects of acute exercise.
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Proteínas Sanguíneas/metabolismo , Exercício Físico/fisiologia , Proteômica , Adulto , Pressão Sanguínea , Doença da Artéria Coronariana/etiologia , Doença da Artéria Coronariana/prevenção & controle , Feminino , Loci Gênicos , Estudo de Associação Genômica Ampla , Humanos , Masculino , Locos de Características Quantitativas , Risco , Adulto JovemRESUMO
Exercise intolerance is a principal feature of heart failure with preserved ejection fraction (HFpEF), whether or not there is evidence of congestion at rest. The degree of functional limitation observed in HFpEF is comparable to patients with advanced heart failure and reduced ejection fraction. Exercise intolerance in HFpEF is characterized by impairments in the physiological reserve capacity of multiple organ systems, but the relative cardiac and extracardiac deficits vary among individuals. Detailed measurements made during exercise are necessary to identify and rank-order the multiorgan system limitations in reserve capacity that culminate in exertional intolerance in a given person. We use a case-based approach to comprehensively review mechanisms of exercise intolerance and optimal approaches to evaluate exercise capacity in HFpEF. We also summarize recent and ongoing trials of novel devices, drugs, and behavioral interventions that aim to improve specific exercise measures such as peak oxygen uptake, 6-min walk distance, heart rate, and hemodynamic profiles in HFpEF. Evaluation during the clinically relevant physiological perturbation of exercise holds promise to improve the precision with which HFpEF is defined and therapeutically targeted.
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Tolerância ao Exercício/fisiologia , Frequência Cardíaca/fisiologia , Volume Sistólico/fisiologia , Função Ventricular Esquerda/fisiologia , Ecocardiografia , Teste de Esforço , Insuficiência Cardíaca/diagnóstico , Insuficiência Cardíaca/fisiopatologia , HumanosRESUMO
BACKGROUND: Ventilatory efficiency (minute ventilation required to eliminate carbon dioxide, VE/VCO2) during exercise potently predicts outcomes in advanced heart failure with reduced ejection fraction, but its prognostic significance for at-risk individuals with preserved left ventricular systolic function is unclear. We aimed to characterize mechanistic determinants and prognostic implications of VE/VCO2 in a single-center dyspneic referral cohort (MGH-ExS [Massachusetts General Hospital Exercise Study]) and in a large sample of community-dwelling participants in the FHS (Framingham Heart Study). METHODS: Maximum incremental cardiopulmonary exercise tests were performed. VE/VCO2 was assessed as the slope pre- and post-ventilatory anaerobic threshold (VE/VCO2pre-VATslope, VE/VCO2post-VATslope), the slope throughout exercise (VE/VCO2overall-slope), and as the lowest 30-second value (VE/VCO2nadir). RESULTS: In the MGH-ExS (N=493, age 56±15 years, 61% women, left ventricular ejection fraction 64±8%), higher VE/VCO2nadir was associated with lower peak exercise cardiac output and steeper increases in exercise pulmonary capillary wedge pressure (both P<0.0001). VE/VCO2nadir (hazard ratio, 1.34 per 1-SD unit [95% CI, 1.10-1.62] P=0.003) was associated with future cardiovascular hospitalization/death and outperformed classical VE/VCO2 measures used in heart failure with reduced ejection fraction (VE/VCO2overall-slope). In FHS (N=1936, age 54±9 years, 53% women), VE/VCO2 measures taken in low-to-moderate intensity exercise (including VE/VCO2pre-VATslope, VE/VCO2nadir) were directly associated with cardiovascular risk factor burden (smoking, Framingham cardiovascular disease risk score, and lower fitness; all P<0.001). CONCLUSIONS: Impaired ventilatory efficiency is associated with cardiovascular risk in the community and with adverse hemodynamic profiles and future hospitalizations/death in a referral population, highlighting the prognostic importance of easily acquired submaximum exercise ventilatory gas exchange measurements in broad populations with preserved left ventricular systolic function.
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Dispneia/fisiopatologia , Insuficiência Cardíaca/fisiopatologia , Hemodinâmica , Pulmão/fisiopatologia , Ventilação Pulmonar , Função Ventricular Esquerda , Adulto , Idoso , Aptidão Cardiorrespiratória , Dispneia/diagnóstico , Dispneia/etiologia , Teste de Esforço , Tolerância ao Exercício , Feminino , Insuficiência Cardíaca/complicações , Insuficiência Cardíaca/diagnóstico , Humanos , Masculino , Pessoa de Meia-Idade , Prognóstico , Sístole , Fatores de TempoRESUMO
Heart failure with preserved ejection fraction (HFpEF) is the most common type of HF in older adults. Although no pharmacological therapy has yet improved survival in HFpEF, exercise training (ExT) has emerged as the most effective intervention to improving functional outcomes in this age-related disease. The molecular mechanisms by which ExT induces its beneficial effects in HFpEF, however, remain largely unknown. Given the strong association between aging and HFpEF, we hypothesized that ExT might reverse cardiac aging phenotypes that contribute to HFpEF pathophysiology and additionally provide a platform for novel mechanistic and therapeutic discovery. Here, we show that aged (24-30 months) C57BL/6 male mice recapitulate many of the hallmark features of HFpEF, including preserved left ventricular ejection fraction, subclinical systolic dysfunction, diastolic dysfunction, impaired cardiac reserves, exercise intolerance, and pathologic cardiac hypertrophy. Similar to older humans, ExT in old mice improved exercise capacity, diastolic function, and contractile reserves, while reducing pulmonary congestion. Interestingly, RNAseq of explanted hearts showed that ExT did not significantly modulate biological pathways targeted by conventional HF medications. However, it reversed multiple age-related pathways, including the global downregulation of cell cycle pathways seen in aged hearts, which was associated with increased capillary density, but no effects on cardiac mass or fibrosis. Taken together, these data demonstrate that the aged C57BL/6 male mouse is a valuable model for studying the role of aging biology in HFpEF pathophysiology, and provide a molecular framework for how ExT potentially reverses cardiac aging phenotypes in HFpEF.
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Envelhecimento/genética , Ecocardiografia Doppler/métodos , Exercício Físico/fisiologia , Insuficiência Cardíaca/fisiopatologia , Volume Sistólico/fisiologia , Animais , Humanos , Masculino , Camundongos , FenótipoRESUMO
BACKGROUND: Abnormal pulmonary arterial pressure (PAP) responses to exercise have been described in select individuals; however, clinical and prognostic implications of exercise pulmonary hypertension (exPH) among broader samples remains unclear. OBJECTIVES: This study sought to investigate the association of exPH with clinical determinants and outcomes. METHODS: The authors studied individuals with chronic exertional dyspnea and preserved ejection fraction who underwent cardiopulmonary exercise testing with invasive hemodynamic monitoring. Exercise pulmonary hypertension was ascertained using minute-by-minute PAP and cardiac output (CO) measurements to calculate a PAP/CO slope, and exPH defined as a PAP/CO slope >3 mm Hg/l/min. The primary outcome was cardiovascular (CV) hospitalization or all-cause mortality. RESULTS: Among 714 individuals (age 57 years, 59% women), 296 (41%) had abnormal PAP/CO slopes. Over a mean follow-up of 3.7 ± 2.9 years, there were 208 CV or death events. Individuals with abnormal PAP/CO slope had a 2-fold increased hazard of future CV or death event (multivariable-adjusted hazard ratio: 2.03; 95% confidence interval: 1.48 to 2.78; p < 0.001). The association of abnormal PAP/CO slope with outcomes remained significant after excluding rest PH (n = 146, hazard ratio: 1.75; 95% confidence interval: 1.21 to 2.54; p = 0.003). Both pre- and post-capillary contributions to exPH independently predicted adverse events (p < 0.001 for both). CONCLUSIONS: Exercise pulmonary hypertension is independently associated with CV event-free survival among individuals undergoing evaluation of chronic dyspnea. These findings suggest incremental value of exercise hemodynamic assessment to resting measurements alone in characterizing the burden of PH in individuals with dyspnea. Whether PH and PH subtypes unmasked by exercise can be used to guide targeted therapeutic interventions requires further investigation.