Hyperlactataemia is a marker of reduced exercise capacity in heart failure with preserved ejection fraction.

AIMS: Heart failure with preserved ejection fraction (HFpEF) is associated with an array of central and peripheral haemodynamic and metabolic changes. The exact pathogenesis of exercise limitation in HFpEF remains uncertain. Our aim was to compare lactate accumulation and central haemodynamic responses to exercise in patients with HFpEF, non-cardiac dyspnoea (NCD), and healthy volunteers. METHODS AND RESULTS: Right heart catheterization with mixed venous blood gas and lactate measurements was performed at rest and during symptom-limited supine exercise. Multivariable analyses were conducted to determine the relationship between haemodynamic and biochemical parameters and their association with exercise capacity. Of 362 subjects, 198 (55%) had HFpEF, 103 (28%) had NCD, and 61 (17%) were healthy volunteers. This included 139 (70%) females with HFpEF, 77 (75%) in NCD (P = 0.41 HFpEF vs. NCD), and 31 (51%) in healthy volunteers (P < 0.001 HFpEF vs. volunteers). The median age was 71 (65, 75) years in HFpEF, 66 (57, 72) years in NCD, and 49 (38, 65) years in healthy volunteers (HFpEF vs. NCD or volunteer, both P < 0.001). Peak workload was lower in HFpEF compared with healthy volunteers [52 W (interquartile range 31-73), 150 W (125-175), P < 0.001], but not NCD [53 W (33, 75), P = 0.85]. Exercise lactate indexed to workload was higher in HFpEF at 0.08 mmol/L/W (0.05-0.11), 0.06 mmol/L/W (0.05-0.08; P = 0.016) in NCD, and 0.04 mmol/L/W (0.03-0.05; P < 0.001) in volunteers. Exercise cardiac index was 4.5 L/min/m2 (3.7-5.5) in HFpEF, 5.2 L/min/m2 (4.3-6.2; P < 0.001) in NCD, and 9.1 L/min/m2 (8.0-9.9; P < 0.001) in volunteers. Oxygen delivery in HFpEF was lower at 1553 mL/min (1175-1986) vs. 1758 mL/min (1361-2282; P = 0.024) in NCD and 3117 mL/min (2667-3502; P < 0.001) in the volunteer group during exercise. Predictors of higher exercise lactate levels in HFpEF following adjustment included female sex and chronic kidney disease (both P < 0.001). CONCLUSIONS: HFpEF is associated with reduced exercise capacity secondary to both central and peripheral factors that alter oxygen utilization. This results in hyperlactataemia. In HFpEF, plasma lactate responses to exercise may be a marker of haemodynamic and cardiometabolic derangements and represent an important target for future potential therapies.

Effect of empagliflozin on myocardial structure and function in patients with type 2 diabetes at high cardiovascular risk: the SIMPLE randomized clinical trial.

To investigate the effects of 13 weeks treatment with empagliflozin in patients with high-risk type-2 diabetes mellitus on echocardiographic measures of left ventricular (LV) structure and function compared to placebo. A total of 91 patients were randomized to treatment with empagliflozin (25 mg/day, n = 45) or matching placebo (n = 45) for 13 weeks. Left ventricular (LV) mass, volumes and geometry as well as measures of LV systolic and diastolic function were measured using echocardiography at baseline and follow up. Mean LV mass index (LVMi) was reduced by - 11.5 g/m2 (95% CI - 56.4; 33.4, p = 0.03) with empagliflozin compared to - 1.4 g/m2 (95% CI - 36.5; 33.8, p = 0.63) for placebo. The proportion of patients with LV hypertrophy was reduced by 16.3% (p = 0.04) in the empagliflozin group compared to 1.1% in the placebo group (p = 1.00). The proportion of patients with left atrial volume index > 34 mL/m2 was reduced by 20.0% (p = 0.02) with empagliflozin compared to 9.5% for placebo (p = 0.45) and the E/e' ratio decreased (∆-0.8 (1.9) vs. ∆0.5 (2.0), p < 0.01). 13 weeks empagliflozin treatment in patients with type-2 diabetes at high CV risk significantly reduced LV mass, improved LV geometry and improved diastolic function compared to placebo.

Comprehensive Physiological Modeling Provides Novel Insights Into Heart Failure With Preserved Ejection Fraction Physiology.

Background Although a rapid rise in left atrial pressure during exertion is considered pathognomonic of heart failure with preserved ejection fraction (HFpEF), the fundamental circulatory determinants of this response are not clear, impacting upon the development of more effective therapies. We aimed to comprehensively describe the circulatory mechanics of patients with HFpEF at rest and during exercise in comparison with controls. Methods and Results We performed simultaneous right-heart catheterization and echocardiography at rest and during exercise in 22 healthy control volunteers and 60 patients with confirmed HFpEF. Using detailed individual patient-level hemodynamic and left ventricular ejection fraction data we performed computer simulations to evaluate the circulatory parameters including the estimated stressed blood volumethat contribute to the resting and exercise pulmonary capillary pressure. At rest and during exercise, left ventricular stiffness (V30, the end-diastolic pressure-volume relationship at a filling pressure of 30 mm Hg), left ventricular elastance, and arterial elastance were all significantly greater in HFpEF than in controls. Stressed blood volume was significantly greater in HFpEF (26.9±5.4 versus 20.2±4.7 mL/kg, P<0.001), becoming even more pronounced during exercise (40.9±3.7 versus 27.5±7.0 mL per 70 kg, P<0.001). During exercise, the magnitude of the change in stressed blood volume (r=0.67, P<0.001) and left ventricular stiffness (r=-0.44, P<0.001) were key determinants of the rise in pulmonary capillary wedge pressure. Further detailed modeling studies showed that the hemodynamic response to exercise results from a complex non-linear interaction between circulatory parameters. Conclusions The circulatory determinants of HFpEF physiology are complex. We identified stressed blood volume at rest and during exercise is a novel, key factor, therebyrepresenting an important potential therapeutic target.

Cardiac and Noncardiac Disease Burden and Treatment Effect of Sacubitril/Valsartan: Insights From a Combined PARAGON-HF and PARADIGM-HF Analysis.

BACKGROUND: The net clinical benefit of cardiac disease-modifying drugs might be influenced by the interaction of different domains of disease burden. We assessed the relative contribution of cardiac, comorbid, and demographic factors in heart failure (HF) and how their interplay might influence HF prognosis and efficacy of sacubitril/valsartan across the spectrum of left ventricular ejection fraction. METHODS: We combined data from 2 global trials that evaluated the efficacy of sacubitril/valsartan compared with a renin-angiotensin antagonist in symptomatic HF patients (PARADIGM-HF [Prospective Comparison of Angiotensin Receptor Neprilysin Inhibitor With an Angiotensin-Converting Enzyme Inhibitor to Determine Impact on Global Mortality and Morbidity in Heart Failure; n=8399] and PARAGON-HF [Prospective Comparison of Angiotensin-Converting Enzyme Inhibitor With Angiotensin Receptors Blockers Global Outcomes in Heart Failure With Preserved Ejection Fraction; n=4796]). We decomposed the previously validated Meta-Analysis Global Group in Chronic Heart Failure risk score into cardiac (left ventricular ejection fraction, New York Heart Association class, blood pressure, time since HF diagnosis, HF medications), noncardiac comorbid (body mass index, creatinine, diabetes, chronic obstructive pulmonary disease, smoking), and demographic (age, gender) categories. Based on these domains, an index representing the balance of cardiac to noncardiac comorbid burden was created (cardiac-comorbid index). Clinical outcomes were time to first HF hospitalization or cardiovascular deaths and all-cause mortality. RESULTS: Higher scores of the cardiac domain were observed in PARADIGM-HF (10 [7-13] versus 5 [3-6], P<0.001) and higher scores of the demographic domain in PARAGON-HF (10 [8-13] versus 5 [2-9], P<0.001). In PARADIGM-HF, the contribution of the cardiac domain to clinical outcomes was greater than the noncardiac domain (P<0.001), while in PARAGON-HF the attributable risk of the comorbid and demographic categories predominated. Individual scores from each sub-domain were linearly associated with the risk of clinical outcomes (P<0.001). Beneficial effects of sacubitril/valsartan were observed in patients with preponderance of cardiac over noncardiac comorbid burden (cardiac-comorbid index >5 points), suggesting a significant treatment effect modification (interaction P<0.05 for both outcomes). CONCLUSIONS: Domains of disease burden are clinically relevant features that influence the prognosis and treatment of patients with HF. The therapeutic benefits of sacubitril/valsartan vary according to the balance of components of disease burden, across different ranges of left ventricular ejection fraction.

Blood pressure and mortality in patients with type 2 diabetes and a recent coronary event in the ELIXA trial.

BACKGROUND: The relationship between blood pressure and mortality in type 2 diabetes (T2DM) is controversial, with concern for increased risk associated with excessively lowered blood pressure. METHODS: We evaluated whether prior cardiovascular disease (CVD) altered the relationship between baseline blood pressure and all-cause mortality in 5852 patients with T2DM and a recent acute coronary syndrome (ACS) who participated in the ELIXA (Evaluation of Lixisenatide in Acute Coronary Syndrome) trial. Risk of death was assessed in Cox models adjusted for age, sex, race, heart rate, BMI, smoking, diabetes duration, insulin use, HbA1c, eGFR, brain natriuretic peptide (BNP), urine albumin/creatinine ratio, treatment allocation and prior coronary revascularization. RESULTS: Although overall there was no significant association between systolic blood pressure (SBP) and mortality (hazard ratio per 10 mmHg lower SBP 1.05 (95% CI 0.99-1.12) P = 0.10), lower SBP was significantly associated with higher risk of death (hazard ratio per 10 mmHg lower SBP 1.13 (95% CI 1.04-1.22) P = 0.002) in 2325 patients with additional CVD (index ACS+ at least one of the following prior to randomization: myocardial infarction other than the index ACS, stroke or heart failure). In 3527 patients with only the index ACS no significant association was observed (hazard ratio per 10 mmHg lower SBP 0.95 (0.86-1.04) P = 0.26; P for interaction 0.005). CONCLUSIONS: The association between blood pressure and mortality was modified by additional CVD history in patients with type 2 diabetes and a recent coronary event. When blood pressures measured after an acute coronary event are used to assess the risk of death in patients with type 2 diabetes, the cardiovascular history needs to be taken into consideration. Trial registration ClinicalTrials.gov number NCT01147250, first posted June 22, 2010.

The role of leptin in human lipid and glucose metabolism: the effects of acute recombinant human leptin infusion in young healthy males.

BACKGROUND: Obese and lean humans treated with leptin have not experienced convincing weight-loss results compared with the dramatic weight losses observed in obese rodents. OBJECTIVE: We sought to investigate the effect of acutely elevating leptin to concentrations observed in obese individuals on muscle and adipose tissue metabolism and muscle signaling in healthy lean males. DESIGN: Healthy, lean, postabsorptive males were infused with either recombinant human leptin (rhleptin; n = 8) or saline (control; n = 8) for 4 h, which elicited leptin concentrations of ~ 20 and ~ 1 ng/mL, respectively. Systemic, skeletal muscle, and adipose tissue fat and glucose metabolism in vivo were assessed before, during, and 2 h after cessation of the infusion. Skeletal muscle biopsy specimens were obtained to quantify changes in signal transducers and activators of transcription-5'AMP-activated protein kinase (STAT-AMPK) signaling. RESULTS: During the infusion of rhleptin, no differences in either systemic, skeletal muscle, or adipose tissue glucose or fat metabolism were observed. These observations were made despite increased activation of STAT (~ 17-fold) and AMPK (1.43-fold) after 1 h of rhleptin infusion. After the rhleptin infusion, an increase in systemic palmitate and fat oxidation was observed (P < 0.0003), which likely was caused by a concomitant increase in skeletal muscle palmitate oxidation (P < 0.02). This was observed despite lowered leptin concentrations and basal skeletal muscle STAT-AMPK signaling. CONCLUSIONS: Elevating circulating leptin concentrations to concentrations comparable with those of obese individuals increases human in vivo skeletal muscle signaling through the AMPK pathway and causes an increase in skeletal muscle fatty acid oxidation. Abdominal adipose tissue was unaffected by the acute physiologic increase in leptin concentrations.

IL-6 selectively stimulates fat metabolism in human skeletal muscle.

Interleukin (IL)-6 is chronically elevated in type 2 diabetes but also during exercise. However, the exact metabolic role, and hence the physiological significance, has not been elucidated. The objective of this study was to investigate the in vivo effect of recombinant human (rh) IL-6 on human fat and glucose metabolism and signaling of both adipose tissue and skeletal muscle. Eight healthy postabsorptive males were infused with either rhIL-6 or saline for 4 h, eliciting IL-6 levels of ∼40 and ∼1 pg/ml, respectively. Systemic, skeletal muscle, and adipose tissue fat and glucose metabolism was assessed before, during, and 2 h after cessation of the infusion. Glucose metabolism was unaffected by rhIL-6. In contrast, rhIL-6 increased systemic fatty acid oxidation approximately twofold after 60 min, and it remained elevated even 2 h after the infusion. The increase in oxidation was followed by an increase in systemic lipolysis. Adipose tissue lipolysis and fatty acid kinetics were unchanged with rhIL-6 compared with saline infusion. Conversely, rhIL-6 infusion caused an increase in skeletal muscle unidirectional fatty acid and glycerol release, indicative of an increase in lipolysis. The increased lipolysis in muscle could account for the systemic changes. Skeletal muscle signaling increased after 1 h of rhIL-6 infusion, indicated by a fourfold increase in the phosphorylated signal transducer and activator of transcription (STAT) 3-to-STAT3 ratio, whereas no changes in phosphorylated AMP-activated protein kinase or acetyl-CoA carboxylase levels could be observed. Our findings suggest that an acute increase in IL-6 at a normophysiological level selectively stimulates lipolysis in skeletal muscle, whereas adipose tissue is unaffected.