Enantiomer-Specific Cardiovascular Effects of the Ketone Body 3-Hydroxybutyrate.

BACKGROUND: The ketone body 3-hydroxybutyrate (3-OHB) increases cardiac output (CO) by 35% to 40% in healthy people and people with heart failure. The mechanisms underlying the effects of 3-OHB on myocardial contractility and loading conditions as well as the cardiovascular effects of its enantiomeric forms, D-3-OHB and L-3-OHB, remain undetermined. METHODS AND RESULTS: Three groups of 8 pigs each underwent a randomized, crossover study. The groups received 3-hour infusions of either D/L-3-OHB (racemic mixture), 100% L-3-OHB, 100% D-3-OHB, versus an isovolumic control. The animals were monitored with pulmonary artery catheter, left ventricle pressure-volume catheter, and arterial and coronary sinus blood samples. Myocardial biopsies were evaluated with high-resolution respirometry, coronary arteries with isometric myography, and myocardial kinetics with D-[11C]3-OHB and L-[11C]3-OHB positron emission tomography. All three 3-OHB infusions increased 3-OHB levels (P<0.001). D/L-3-OHB and L-3-OHB increased CO by 2.7 L/min (P<0.003). D-3-OHB increased CO nonsignificantly (P=0.2). Circulating 3-OHB levels correlated with CO for both enantiomers (P<0.001). The CO increase was mediated through arterial elastance (afterload) reduction, whereas contractility and preload were unchanged. Ex vivo, D- and L-3-OHB dilated coronary arteries equally. The mitochondrial respiratory capacity remained unaffected. The myocardial 3-OHB extraction increased only during the D- and D/L-3-OHB infusions. D-[11C]3-OHB showed rapid cardiac uptake and metabolism, whereas L-[11C]3-OHB demonstrated much slower pharmacokinetics. CONCLUSIONS: 3-OHB increased CO by reducing afterload. L-3-OHB exerted a stronger hemodynamic response than D-3-OHB due to higher circulating 3-OHB levels. There was a dissocitation between the myocardial metabolism and hemodynamic effects of the enantiomers, highlighting L-3-OHB as a potent cardiovascular agent with strong hemodynamic effects.

Cardiovascular Effects of Oral Ketone Ester Treatment in Patients With Heart Failure With Reduced Ejection Fraction: A Randomized, Controlled, Double-Blind Trial.

BACKGROUND: Heart failure triggers a shift in myocardial metabolic substrate utilization, favoring the ketone body 3-hydroxybutyrate as energy source. We hypothesized that 14-day treatment with ketone ester (KE) would improve resting and exercise hemodynamics and exercise capacity in patients with heart failure with reduced ejection fraction. METHODS: In a randomized, double-blind cross-over study, nondiabetic patients with heart failure with reduced ejection fraction received 14-day KE and 14-day isocaloric non-KE comparator regimens of 4 daily doses separated by a 14-day washout period. After each treatment period, participants underwent right-sided heart catheterization, echocardiography, and blood sampling at plasma trough levels and after dosing. Participants underwent an exercise hemodynamic assessment after a second dosing. The primary end point was resting cardiac output (CO). Secondary end points included resting and exercise pulmonary capillary wedge pressure and peak exercise CO and metabolic equivalents. RESULTS: We included 24 patients with heart failure with reduced ejection fraction (17 men; 65±9 years of age; all White). Resting CO at trough levels was higher after KE compared with isocaloric comparator (5.2±1.1 L/min versus 5.0±1.1 L/min; difference, 0.3 L/min [95% CI, 0.1-0.5), and pulmonary capillary wedge pressure was lower (8±3 mm Hg versus 11±3 mm Hg; difference, -2 mm Hg [95% CI, -4 to -1]). These changes were amplified after KE dosing. Across all exercise intensities, KE treatment was associated with lower mean exercise pulmonary capillary wedge pressure (-3 mm Hg [95% CI, -5 to -1] ) and higher mean CO (0.5 L/min [95% CI, 0.1-0.8]), significantly different at low to moderate steady-state exercise but not at peak. Metabolic equivalents remained similar between treatments. In exploratory analyses, KE treatment was associated with 18% lower NT-proBNP (N-terminal pro-B-type natriuretic peptide; difference, -98 ng/L [95% CI, -185 to -23]), higher left ventricular ejection fraction (37±5 versus 34±5%; P=0.01), and lower left atrial and ventricular volumes. CONCLUSIONS: KE treatment for 14 days was associated with higher CO at rest and lower filling pressures, cardiac volumes, and NT-proBNP levels compared with isocaloric comparator. These changes persisted during exercise and were achieved on top of optimal medical therapy. Sustained modulation of circulating ketone bodies is a potential treatment principle in patients with heart failure with reduced ejection fraction. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique identifier: NCT05161650.

Lactate infusion elevates cardiac output through increased heart rate and decreased vascular resistance: a randomised, blinded, crossover trial in a healthy porcine model.

BACKGROUND: Lactate is traditionally recognized as a by-product of anaerobic metabolism. However, lactate is a preferred oxidative substrate for stressed myocardium. Exogenous lactate infusion increases cardiac output (CO). The exact mechanism underlying this mechanism has yet to be elucidated. The aim of this study was to investigate the cardiovascular mechanisms underlying the acute haemodynamic effects of exogenous lactate infusion in an experimental model of human-sized pigs. METHODS: In this randomised, blinded crossover study in eight 60-kg-pigs, the pigs received infusions with one molar sodium lactate and a control infusion of tonicity matched hypertonic saline in random order. We measured CO and pulmonary pressures using a pulmonary artery catheter. A pressure-volume admittance catheter in the left ventricle was used to measure contractility, afterload, preload and work-related parameters. RESULTS: Lactate infusion increased circulating lactate levels by 9.9 mmol/L (95% confidence interval (CI) 9.1 to 11.0) and CO by 2.0 L/min (95% CI 1.2 to 2.7). Afterload decreased as arterial elastance fell by  -1.0 mmHg/ml (95% CI  -2.0 to  -0.1) and systemic vascular resistance decreased by  -548 dynes/s/cm5 (95% CI  -261 to  -835). Mixed venous saturation increased by 11 percentage points (95% CI 6 to 16), whereas ejection fraction increased by 16.0 percentage points (95% CI 1.1 to 32.0) and heart rate by 21 bpm (95% CI 8 to 33). No significant changes in contractility nor preload were observed. CONCLUSION: Lactate infusion increased cardiac output by increasing heart rate and lowering afterload. No differences were observed in left ventricular contractility or preload. Lactate holds potential as a treatment in situations with lowered CO and should be investigated in future clinical studies.

Myocardial work across different etiologies of right ventricular dysfunction and healthy controls.

Evaluating right ventricular (RV) function remains a challenge. Recently, novel echocardiographic assessment of RV myocardial work (RVMW) by non-invasive pressure-strain loops was proposed. This enables evaluation of right ventriculoarterial coupling and quantifies RV dyssynchrony and post-systolic shortening. We aimed to assess RVMW in patients with different etiologies of RV dysfunction and healthy controls. We investigated healthy controls (n=17), patients with severe functional tricuspid regurgitation (FTR; n=22), and patients with precapillary pulmonary hypertension (PCPH; n=20). Echocardiography and right heart catheterization were performed to assess 1) RV global constructive work (RVGCW; work needed for systolic myocardial shortening and isovolumic relaxation), 2) RV global wasted work (RVGWW; myocardial shortening following pulmonic valve closure), and 3) RV global work efficiency (RVGWE; describes the relation between RV constructive and wasted work). RVGCW correlated with invasive RV stroke work index (r=0.66, P<0.001) and increased in tandem with higher afterload, i.e., was low in healthy controls (454±73 mmHg%), moderate in patients with FTR (687±203 mmHg%), and highest among patients with PCPH (881±255 mmHg%). RVGWE was lower and RVGWW was higher in patients with FTR (86±8% and 91 mmHg% [53-140]) or PCPH (86±10% and 110 mmHg% [66-159]) as compared with healthy controls (96±3% and 10 mmHg%). RVMW by echocardiography provides a promising index of RV function to discriminate between patients with RV volume or pressure overload. The prognostic value of this measure needs to be settled in future studies.

Circulating 3-hydroxy butyrate predicts mortality in patients with chronic heart failure with reduced ejection fraction.

AIMS: In patients with chronic heart failure with reduced ejection fraction (HFrEF), myocardial ketone metabolism is increased and short-term treatment with the ketone body 3-hydroxy butyrate (3-OHB) has beneficial haemodynamic effects. In patients with HFrEF, we investigated whether the level of circulating 3-OHB predicted all-cause mortality and sought to identify correlations between patient characteristics and circulating 3-OHB levels. METHODS AND RESULTS: We conducted a cohort study in 218 patients with HFrEF. Plasma 3-OHB levels were measured using high-performance liquid chromatography tandem mass spectrometry. Data on all-cause mortality were obtained by reviewing the patients' medical records, which are linked to the national 'Central Person Registry' that registers the timing of all deaths in the country. Mean left ventricular ejection fraction was 35 ± 8.6%, mean age was 67 ± 10 years, 54% were New York Heart Association II, and 27% had type 2 diabetes mellitus. Median follow-up time was 7.3 (interquartile range 6.3-8.4) years. We observed large variations in 3-OHB levels between patients (median 59 µM, range: 14-694 µM). Patients with 3-OHB levels above the median displayed a markedly increased risk of death compared with those with low levels {hazard ratio [HR]: 2.1 [95% confidence interval (CI): 1.3-3.5], P = 0.003}. In a multivariate analysis, 3-OHB predicted mortality independently of known chronic heart failure risk factors [HR: 1.004 (95% CI: 1.001-1.007), P = 0.02] and with a similar statistical strength as N-terminal pro-brain natriuretic peptide (NT-proBNP) [HR: 1.0005 (95% CI: 1.000-1.001), P = 0.02]. For every 100 µmol increase in plasma 3-OHB, the hazard of death increased by 49%. The following factors significantly predicted 3-OHB levels in the univariate analysis: free fatty acids (FFAs) [ß: 238 (95% CI: 185-292), P < 0.0001], age [ß: 2.43 (95% CI: 1.14-3.72), P < 0.0001], plasma insulin {ß: -0.28 [95% CI: -0.54-(-0.02)], P = 0.036}, body mass index {ß: -3.15 [95% CI: -5.26-(-0.05)], P = 0.046}, diabetes [ß: 44.49 (95% CI: 14.84-74.14), P = 0.003], glycosylated haemoglobin [ß: 1.92 (95% CI: 0.24-3.59), P = 0.025], New York Heart Association class [ß: 26.86 (95% CI: 5.99-47.72), P = 0.012], and NT-proBNP [ß: 0.03 (95% CI: 0.01-0.04), P = 0.001]. In a multivariate analysis, only FFAs predicted 3-OHB levels [ß: 216 (95% CI: 165-268), P > 0.001]. CONCLUSIONS: In patients with HFrEF, circulating 3-OHB was a strong predictor of all-cause mortality independently of NT-proBNP. Circulating FFAs were the best predictor of 3-OHB levels.

Effects of ketone body 3-hydroxybutyrate on cardiac and mitochondrial function during donation after circulatory death heart transplantation.

Normothermic regional perfusion (NRP) allows assessment of therapeutic interventions prior to donation after circulatory death transplantation. Sodium-3-hydroxybutyrate (3-OHB) increases cardiac output in heart failure patients and diminishes ischemia-reperfusion injury, presumably by improving mitochondrial metabolism. We investigated effects of 3-OHB on cardiac and mitochondrial function in transplanted hearts and in cardiac organoids. Donor pigs (n = 14) underwent circulatory death followed by NRP. Following static cold storage, hearts were transplanted into recipient pigs. 3-OHB or Ringer's acetate infusions were initiated during NRP and after transplantation. We evaluated hemodynamics and mitochondrial function. 3-OHB mediated effects on contractility, relaxation, calcium, and conduction were tested in cardiac organoids from human pluripotent stem cells. Following NRP, 3-OHB increased cardiac output (P < 0.0001) by increasing stroke volume (P = 0.006), dP/dt (P = 0.02) and reducing arterial elastance (P = 0.02). Following transplantation, infusion of 3-OHB maintained mitochondrial respiration (P = 0.009) but caused inotropy-resistant vasoplegia that prevented weaning. In cardiac organoids, 3-OHB increased contraction amplitude (P = 0.002) and shortened contraction duration (P = 0.013) without affecting calcium handling or conduction velocity. 3-OHB had beneficial cardiac effects and may have a potential to secure cardiac function during heart transplantation. Further studies are needed to optimize administration practice in donors and recipients and to validate the effect on mitochondrial function.

Ketone body 3-hydroxybutyrate elevates cardiac output through peripheral vasorelaxation and enhanced cardiac contractility.

The ketone body 3-hydroxybutyrate (3-OHB) increases cardiac output and myocardial perfusion without affecting blood pressure in humans, but the cardiovascular sites of action remain obscure. Here, we test the hypothesis in rats that 3-OHB acts directly on the heart to increase cardiac contractility and directly on blood vessels to lower systemic vascular resistance. We investigate effects of 3-OHB on (a) in vivo hemodynamics using echocardiography and invasive blood pressure measurements, (b) isolated perfused hearts in Langendorff systems, and (c) isolated arteries and veins in isometric myographs. We compare Na-3-OHB to equimolar NaCl added to physiological buffers or injection solutions. At plasma concentrations of 2-4 mM in vivo, 3-OHB increases cardiac output (by 28.3±7.8%), stroke volume (by 22.4±6.0%), left ventricular ejection fraction (by 13.3±4.6%), and arterial dP/dtmax (by 31.9±11.2%) and lowers systemic vascular resistance (by 30.6±11.2%) without substantially affecting heart rate or blood pressure. Applied to isolated perfused hearts at 3-10 mM, 3-OHB increases left ventricular developed pressure by up to 26.3±7.4 mmHg and coronary perfusion by up to 20.2±9.5%. Beginning at 1-3 mM, 3-OHB relaxes isolated coronary (EC50=12.4 mM), cerebral, femoral, mesenteric, and renal arteries as well as brachial, femoral, and mesenteric veins by up to 60% of pre-contraction within the pathophysiological concentration range. Of the two enantiomers that constitute racemic 3-OHB, D-3-OHB dominates endogenously; but tested separately, the enantiomers induce similar vasorelaxation. We conclude that increased cardiac contractility and generalized systemic vasorelaxation can explain the elevated cardiac output during 3-OHB administration. These actions strengthen the therapeutic rationale for 3-OHB in heart failure management.

Impact of Coronary Artery Disease in Women With Newly Diagnosed Heart Failure and Reduced Ejection Fraction.

BACKGROUND: The representation of women in heart failure studies has been inadequate, resulting in a knowledge gap regarding the prognostic impact of coronary artery disease (CAD) on all-cause mortality in women with newly diagnosed heart failure and reduced ejection fraction (HFrEF). OBJECTIVES: This study aims to assess the prognostic impact of CAD in women with HFrEF. METHODS: Using the Western Denmark Heart Registry, the authors identified 891 women and 2,403 men referred for first-time coronary angiography because of HFrEF. The authors stratified for presence of CAD, estimated 10-year all-cause mortality, and calculated crude and adjusted HRs (aHRs) with 95% CIs. RESULTS: The 10-year mortality was 60% in women with CAD and 27% in women without CAD; for men, the corresponding numbers were 54% and 36%. When adjusted for comorbidities, women without CAD had a lower relative 10-year mortality than men without CAD (aHR: 0.73; 95% CI: 0.58-0.91), whereas women with CAD had similar relative mortality as men with CAD (aHR: 1.00; 95% CI: 0.81-1.24) (Pinteraction = 0.037). Assessed by the number of coronary vessels with significant stenosis, CAD extent was associated with mortality for both women (P < 0.01) and men (P < 0.01). However, compared to those without CAD, the aHR was higher for women with any degree of CAD (aHR ranging from 1.61 [95% CI: 1.09-2.38] for diffuse CAD to 2.01 [95% CI: 1.19-3.40] for 3-vessel disease) than for men with 3-vessel disease (aHR: 1.51; 95% CI: 1.19-1.91). CONCLUSIONS: In patients with newly diagnosed HFrEF, the presence and extent of CAD has significantly greater prognostic impact among women than among men.

Beneficial Effects of Ketone Ester in Patients With Cardiogenic Shock: A Randomized, Controlled, Double-Blind Trial.

BACKGROUND: Cardiogenic shock (CS) is a life-threatening condition with sparse treatment options. The ketone body 3-hydroxybutyrate has favorable hemodynamic effects in patients with stable chronic heart failure. Yet, the hemodynamic effects of exogenous ketone ester (KE) in patients with CS remain unknown. OBJECTIVES: The authors aimed to assess the hemodynamic effects of single-dose enteral treatment with KE in patients with CS. METHODS: In a double-blind, crossover study, 12 patients with CS were randomized to an enteral bolus of KE and isocaloric, isovolumic placebo containing maltodextrin. Patients were assessed with pulmonary artery catheterization, arterial blood samples, echocardiography, and near-infrared spectroscopy for 3 hours following each intervention separated by a 3-hour washout period. RESULTS: KE increased circulating 3-hydroxybutyrate (2.9 ± 0.3 mmol/L vs 0.2 ± 0.3 mmol/L, P < 0.001) and was associated with augmented cardiac output (area under the curve of relative change: 61 ± 22 L vs 1 ± 18 L, P = 0.044). Also, KE increased cardiac power output (0.07 W [95% CI: 0.01-0.14]; P = 0.037), mixed venous saturation (3 percentage points [95% CI: 1-5 percentage points]; P = 0.010), and forearm perfusion (3 percentage points [95% CI: 0-6 percentage points]; P = 0.026). Right (P = 0.048) and left (P = 0.017) ventricular filling pressures were reduced whereas heart rate and mean arterial and pulmonary arterial pressures remained similar. Left ventricular ejection fraction improved by 4 percentage points (95% CI: 2-6 percentage points; P = 0.005). Glucose levels decreased by 2.6 mmol/L (95% CI: -5.2 to 0.0; P = 0.047) whereas insulin levels remained unaltered. CONCLUSIONS: Treatment with KE improved cardiac output, biventricular function, tissue oxygenation, and glycemic control in patients with CS (Treatment With the Ketone Body 3-hydroxybutyrate in Patients With Cardiogenic Shock [KETO-SHOCK1]; NCT04642768).

Stimulation of the Hydroxycarboxylic Acid Receptor 2 With the Ketone Body 3-Hydroxybutyrate and Niacin in Patients With Chronic Heart Failure: Hemodynamic and Metabolic Effects.

Background The ketone body 3-hydroxybutyrate (3-OHB) increases cardiac output (CO) in patients with heart failure through unknown mechanisms. 3-OHB activates the hydroxycarboxylic acid receptor 2 (HCA2), which increases prostaglandins and suppresses circulating free fatty acids. We investigated whether the cardiovascular effects of 3-OHB involved HCA2 activation and if the potent HCA2-stimulator niacin may increase CO. Methods and Results Twelve patients with heart failure with reduced ejection fraction were included in a randomized crossover study and examined by right heart catheterization, echocardiography, and blood sampling on 2 separate days. On study day 1, patients received aspirin to block the HCA2 downstream cyclooxygenase enzyme, followed by 3-OHB and placebo infusions in random order. We compared the results with those of a previous study in which patients received no aspirin. On study day 2, patients received niacin and placebo. The primary end point was CO. 3-OHB increased CO (2.3 L/min, P<0.01), stroke volume (19 mL, P<0.01), heart rate (10 bpm, P<0.01), and mixed venous saturation (5%, P<0.01) with preceding aspirin. 3-OHB did not change prostaglandin levels, neither in the ketone/placebo group receiving aspirin nor the previous study cohort. Aspirin did not block 3-OHB-induced changes in CO (P=0.43). 3-OHB decreased free fatty acids by 58% (P=0.01). Niacin increased prostaglandin D2 levels by 330% (P<0.02) and reduced free fatty acids by 75% (P<0.01) but did not affect CO. Conclusions The acute increase in CO during 3-OHB infusion was not modified by aspirin, and niacin had no hemodynamic effects. These findings show that HCA2 receptor-mediated effects were not involved in the hemodynamic response to 3-OHB. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04703361.

Hemodynamic Effects of Ketone Bodies in Patients With Pulmonary Hypertension.

Background Pulmonary arterial hypertension (PAH) or chronic thromboembolic pulmonary hypertension (CTEPH) are debilitating diseases with a high mortality. Despite emerging treatments, pulmonary vascular resistance frequently remains elevated. However, the ketone body 3-hydroxybutyrate (3-OHB) may reduce pulmonary vascular resistance in these patients. Hence, the aim was to assess the hemodynamic effects of 3-OHB in patients with PAH or CTEPH. Methods and Results We enrolled patients with PAH (n=10) or CTEPH (n=10) and residual pulmonary hypertension. They received 3-OHB infusion and placebo (saline) for 2 hours in a randomized crossover study. Invasive hemodynamic and echocardiography measurements were performed. Furthermore, we investigated the effects of 3-OHB on the right ventricle of isolated hearts and isolated pulmonary arteries from Sprague-Dawley rats. Ketone body infusion increased circulating 3-OHB levels from 0.5±0.5 to 3.4±0.7 mmol/L (P<0.001). Cardiac output improved by 1.2±0.1 L/min (27±3%, P<0.001), and right ventricular annular systolic velocity increased by 1.4±0.4 cm/s (13±4%, P=0.002). Pulmonary vascular resistance decreased by 1.3±0.3 Wood units (18%±4%, P<0.001) with no significant difference in response between patients with PAH and CTEPH. In the rat studies, 3-OHB administration was associated with decreased pulmonary arterial tension compared with saline administration (maximal relative tension difference: 12±2%, P<0.001) and had no effect on right ventricular systolic pressures (P=0.63), whereas pressures rose at a slower pace (dP/dtmax, P=0.02). Conclusions In patients with PAH or CTEPH, ketone body infusion improves cardiac output and decreases pulmonary vascular resistance. Experimental rat studies support that ketone bodies relax pulmonary arteries. Long-term studies are warranted to assess the clinical role of hyperketonemia. Registration URL: https://www.clinicaltrials.gov; Unique identifier: NCT04615754.

Metoprolol Improves Left Ventricular Longitudinal Strain at Rest and during Exercise in Obstructive Hypertrophic Cardiomyopathy.

BACKGROUND: Patients with obstructive hypertrophic cardiomyopathy (HCM) often experience symptoms of heart failure upon exertion despite having normal left ventricular (LV) ejection fractions. Longitudinal strain (LS) may be a more sensitive marker of systolic dysfunction in patients with LV hypertrophy. The aims of this study were to characterize LV segmental LS and global LS (GLS) at rest and during exercise and to assess if first-line treatment with ß-blockers improves LV systolic performance. METHODS: Twenty-nine patients with obstructive HCM and New York Heart Association functional class ≥ II symptoms were enrolled in a double-blind, placebo-controlled, randomized crossover trial. Patients received metoprolol 150 mg or placebo for two consecutive 2-week periods in random order. Echocardiographic assessment with speckle-tracking-derived LS was performed at rest and during peak exercise at the end of each treatment period. RESULTS: During placebo treatment, resting values of segmental LS showed an apical-basal difference of -10.3% (95% CI, -12.7% to -7.8%; P < .0001), with a severely abnormal value of the basal segment of -9.3 ± 4.2%. Treatment with metoprolol was associated with more negative LS values of the apical segment (-2.8%; 95% CI, -4.2% to -1.3%; P < .001) and the mid segment (-1.1%; 95% CI, -2.0% to -0.3%; P = .007). During peak exercise there was a deterioration in LV GLS, but treatment with metoprolol was associated with more negative peak exercise LV GLS (-1.3 %; 95% CI, -2.6% to -0.1%; P = .03). CONCLUSIONS: Systolic performance assessed by LV GLS showed impaired values at rest and during exercise, with severely depressed values of the basal and mid segments. Treatment with metoprolol improved LV GLS upon exercise, indicating a beneficial effect of ß-blocker treatment on LV systolic function.

Clinical use of cardiac 18 F-FDG viability PET: a retrospective study of 44 patients undergoing post-test revascularization.

The coupling between coronary artery disease and the development of ischemic heart failure is well-established. For these patients, assessment of potentially viable but dysfunctional myocardial tissue (hibernation) is considered critical to guide optimal surgical treatment. Assessment with positron emission tomography (PET) theoretically provides measurements of hibernating tissue and maximal myocardial glucose uptake (MGU) in all cardiac territories. However, the clinical benefits of these measures are not thoroughly studied. We therefore aimed to investigate whether cardiac viability testing with combined Rubidium-82 (82Rb) and 18F-fluorodeoxyglucose (18F-FDG) predicts post-intervention improvement in left ventricle ejection fraction (LVEF) and survival. This retrospective study consisted of 131 patients with ischemic heart failure referred for dynamic 82Rb/18F-FDG PET viability testing prior to revascularization. The FDG viability scan was done during a hyperinsulinemic-euglycemic clamp and included PET measures static FDG hibernation and absolute MGU as well as myocardial blood flow and coronary flow reserve. In total, 44/131 patients undergoing viability testing were subsequently revascularized. Following revascularization, 26 patients had LVEF improvement of at least 5% while 18 patients had no improvement. A poor correlation between areas of intervention and areas of hibernation was observed. Receiver operating characteristics for all PET metrics did not predict improvement in LVEF. Furthermore, hibernation failed to predict survival regardless of whether patients underwent subsequent revascularization. Dynamic viability PET metrics (hibernation and MGU) do not predict post-intervention improvement in LVEF or overall survival in ischemic heart failure patients undergoing revascularization. In a clinical setting, the value of these measurements may therefore be limited. Kindly check and confirm the Given names and Family names for all the authors.All names are correct!

Effects of Metoprolol on Exercise Hemodynamics in Patients With Obstructive Hypertrophic Cardiomyopathy.

BACKGROUND: The relationship between exercise hemodynamics, loading conditions, and medical treatment in patients with obstructive hypertrophic cardiomyopathy (HCM) is incompletely understood. OBJECTIVES: This study aimed to investigate the effect of metoprolol on invasive hemodynamic parameters at rest and during exercise in patients with obstructive HCM. METHODS: This randomized, double-blind, placebo-controlled crossover trial enrolled 28 patients with obstructive HCM and New York Heart Association functional class ≥II. Patients were randomized to initiate either metoprolol 150 mg or placebo for 2 consecutive 2-week periods. Right-heart catheterization and echocardiography were performed at rest and during exercise at the end of each treatment period. The primary outcome was the difference in pulmonary capillary wedge pressure (ΔPCWP) between peak exercise and rest. RESULTS: No treatment effect on ΔPCWP was observed between metoprolol and placebo treatment (21 ± 9 mm Hg vs 23 ± 9 mm Hg; P = 0.12). At rest, metoprolol lowered heart rate (P < 0.0001), left ventricular outflow tract (LVOT) gradient (P = 0.01), and increased left ventricular end-diastolic volume (P = 0.02) and stroke volume (SV) (+6.4; 95% CI: 0.02-17.7; P = 0.049). During peak exercise, metoprolol was associated with a lower heart rate (P < 0.0001), a lower LVOT gradient (P = 0.0005), lesser degree of mitral regurgitation (P = 0.004), and increased SV (+9 mL; 95% CI: 2-15 mL; P = 0.008). CONCLUSIONS: In patients with obstructive HCM, exercise was associated with an abnormal rise in PCWP, which was unaffected by metoprolol. However, metoprolol increased SV at rest and peak exercise following changes in end-diastolic volume, LVOT gradient, and degree of mitral regurgitation. (The Effect of Metoprolol in Patients With Hypertrophic Obstructive Cardiomyopathy [TEMPO]; NCT03532802).

Myocardial efficiency in patients with different aetiologies and stages of heart failure.

AIMS: Myocardial external efficiency (MEE) is the ratio of cardiac work in relation with energy expenditure. We studied MEE in patients with different aetiologies and stages of heart failure (HF) to discover the role and causes of deranged MEE. In addition, we explored the impact of patient characteristics such as sex, body mass index (BMI), and age on myocardial energetics. METHODS AND RESULTS: Cardiac energetic profiles were assessed with 11C-acetate positron emission tomography (PET) and left ventricular ejection fraction (LVEF) was acquired with echocardiography. MEE was studied in 121 participants: healthy controls (n = 20); HF patients with reduced (HFrEF; n = 25) and mildly reduced (HFmrEF; n = 23) LVEF; and patients with asymptomatic (AS-asymp; n = 38) and symptomatic (AS-symp; n = 15) aortic stenosis (AS). Reduced MEE coincided with symptoms of HF irrespective of aetiology and declined in tandem with deteriorating LVEF. Patients with AS-symp and HFmrEF had reduced MEE as compared with controls (22.2 ± 4.9%, P = 0.041 and 20.0 ± 4.2%, P < 0.001 vs. 26.1 ± 5.8% in controls) and a further decline was observed in patients with HFrEF (14.7 ± 6.3%, P < 0.001). Disproportionate left ventricular hypertrophy was a major cause of reduced MEE. Female sex (P < 0.001), a lower BMI (P = 0.001), and advanced age (P = 0.03) were associated with a lower MEE. CONCLUSION: MEE was reduced in patients with HFrEF, HFmrEF, and HF due to pressure overload and MEE may therefore constitute a treatment target in HF. Patients with LVH, advanced age, female sex, and low BMI had more pronounced reduction in MEE and personalized treatment within these patient subgroups could be relevant.

Randomized Trial of Metoprolol in Patients With Obstructive Hypertrophic Cardiomyopathy.

BACKGROUND: The use of ß-adrenergic receptor blocking agents in symptomatic patients with obstructive hypertrophic cardiomyopathy (HCM) rests on clinical experience and observational cohort studies. OBJECTIVES: This study aimed to investigate the effects of metoprolol on left ventricular outflow tract (LVOT) obstruction, symptoms, and exercise capacity in patients with obstructive HCM. METHODS: This double-blind, placebo-controlled, randomized crossover trial enrolled 29 patients with obstructive HCM and New York Heart Association (NYHA) functional class II or higher symptoms from May 2018 to September 2020. Patients received metoprolol or placebo for 2 consecutive 2-week periods in random order. The effect parameters were LVOT gradients, NYHA functional class, Canadian Cardiovascular Society (CCS) angina class, Kansas City Cardiomyopathy Questionnaire Overall Summary Score (KCCQ-OSS), and cardiopulmonary exercise testing. RESULTS: Compared with placebo, the LVOT gradient during metoprolol was lower at rest (25 mm Hg [interquartile range (IQR): 15-58 mm Hg] vs 72 mm Hg [IQR: 28-87 mm Hg]; P = 0.007), at peak exercise (28 mm Hg [IQR: 18-40 mm Hg] vs 62 mm Hg [IQR: 31-113 mm Hg]; P < 0.001), and postexercise (45 mm Hg [IQR: 24-100 mm Hg] vs 115 mm Hg [IQR: 55-171 mm Hg]; P < 0.0001). During metoprolol treatment, 14% of patients were in NYHA functional class III or higher compared with 38% of patients receiving placebo (P < 0.01). Similarly, no patients were in CCS class III or higher during metoprolol treatment compared with 10% during placebo treatment (P < 0.01). These findings were confirmed by higher KCCQ-OSS during metoprolol treatment (76.2 ± 16.2 vs 73.8 ± 19.5; P = 0.039). Measures of exercise capacity, peak oxygen consumption, and N-terminal pro-B-type natriuretic peptide did not differ between the study arms. CONCLUSIONS: Compared with placebo, metoprolol reduced LVOT obstruction at rest and during exercise, provided symptom relief, and improved quality of life in patients with obstructive HCM. Maximum exercise capacity remained unchanged. (The Effect of Metoprolol in Patients with Hypertrophic Obstructive Cardiomyopathy [TEMPO]; NCT03532802).

A systematic approach to weaning from extracorporeal membrane oxygenation in patients with refractory cardiac failure.

BACKGROUND: Veno-arterial extracorporeal membrane oxygenation (V-A ECMO) is commonly used to provide haemodynamic support for patients with severe cardiac failure. However, timing ECMO weaning remains challenging. We aimed to examine if an integrative weaning approach based on predefined haemodynamic, respiratory and echocardiographic criteria is associated with successful weaning. METHODS: All patients weaned from ECMO between April 2017 and April 2019 at Aarhus University Hospital, Denmark, were consecutively enrolled. Predefined haemodynamic, respiratory and echocardiographic criteria were assessed before and during ECMO flow reduction. A weaning attempt was commenced in haemodynamic stable patients and patients remaining stable at minimal flow were weaned from ECMO. Comparisons were made between patients who met the criteria for weaning at first attempt and patients who did not meet these criteria. Patients completing a full weaning attempt with no further need for mechanical support within 24 h were defined as successfully weaned. RESULTS: A total of 38 patients were included in the study, of whom 26 (68%) patients met the criteria for weaning. Among these patients, 25 (96%) could be successfully weaned. Successfully weaned patients were younger and had less need for inotropic support and ECMO duration was shorter. Fulfilling the weaning criteria was associated with successful weaning and both favourable 30-d survival and survival to discharge. CONCLUSION: An integrative weaning approach based on haemodynamic, respiratory and echocardiographic criteria may strengthen the clinical decision process in predicting successful weaning in patients receiving ECMO for refractory cardiac failure.

The impact of the glucagon-like peptide-1 receptor agonist liraglutide on natriuretic peptides in heart failure patients with reduced ejection fraction with and without type 2 diabetes.

AIM: To assess the effect of liraglutide, a glucagon-like peptide-1 receptor agonist, on urinary sodium excretion as well as on circulating adrenomedullin and copeptin levels in patients with type 2 diabetes (T2D). MATERIALS AND METHODS: In the LIVE study, patients (n = 241) with left ventricular ejection fraction ≤45% were randomized to liraglutide 1.8 mg daily or placebo for 24 weeks, and 30% had a concomitant diagnosis of T2D. Plasma levels of N-terminal brain-natriuretic-peptide (NT-proBNP) (a predefined secondary endpoint), midregional pro-atrial-natriuretic-peptide (MR-proANP), midregional pro-adrenomedullin (MR-proADM) and copeptin were measured at baseline and after 24 weeks in this substudy. The potential effect modification of T2D was assessed. RESULTS: In the eligible subgroup of 231 patients with available biomarkers (115 randomized to liraglutide and 116 to placebo), MR-proANP decreased by 12% (P = .002) and NT-proBNP by 9% (P = .009) during liraglutide treatment compared with placebo at week 24. Interaction with T2D for the treatment effect of change in MR-proANP and NT-proBNP levels was P = .003 and P = .03, respectively. Consequently, in patients with T2D, liraglutide decreased MR-proANP by 27% (P < .001) and NT-proBNP by 25% (P = .02) compared with placebo, whereas no change was observed in patients without T2D. There was no effect of liraglutide on MR-proADM (P = .10) or copeptin (P = .52). CONCLUSION: Liraglutide decreased the A- and B-type natriuretic peptides significantly in patients with heart failure with reduced ejection fraction (HFrEF) and concomitant T2D, suggesting a beneficial mechanism of liraglutide in T2D patients with HFrEF.

Heart rate increases in liraglutide treated chronic heart failure patients: association with clinical parameters and adverse events.

Background. Liraglutide, a glucagon-like peptide-1 agonist, is used for treatment of type 2 diabetes and has beneficial cardiovascular properties. However, treatment increases heart rate (HR) and possibly the risk of cardiovascular events in chronic heart failure (CHF) patients. We investigated potential associations between HR changes and clinical, laboratory and echocardiographic parameters and clinical events in liraglutide treated CHF patients. Methods. This was a sub-study of the LIVE study. CHF patients (N = 241) with a left ventricular ejection fraction ≤45% were randomised to 1.8 mg liraglutide daily or placebo for 24 weeks. Electrocardiograms (N = 117) and readouts from cardiac implanted electronic devices (N = 20) were analysed for HR and arrhythmias. Results. In patients with sinus rhythm (SR), liraglutide increased HR by 8 ± 9 bpm (pulse measurements), 9 ± 9 bpm (ECG measurements) and 9 ± 6 bpm (device readouts) versus placebo (all p<.005). Increases in HR correlated with liraglutide dose (p=.01). HR remained unchanged in patients without SR. Serious cardiac adverse events were not associated with HR changes. Conclusions. During 6 months of treatment, HR increased substantially in CHF patients with SR treated with liraglutide but was not associated with adverse events. The long-term clinical significance of increased HR in liraglutide treated CHF patients needs to be determined.

Optimizing heart failure treatment following cardiac resynchronization therapy.

BACKGROUND: Device therapy in addition to medical treatment improves prognosis in a subset of patients with heart failure and reduced ejection fraction. However, some patients remain symptomatic or their heart failure even progresses despite cardiac resynchronization therapy (CRT). The aim of the study was to evaluate the proportion of patients who could benefit from optimization of medical therapy using sacubitril/valsartan, ivabradine, or both following CRT implantation. METHODS: We conducted a post hoc analysis of a single-centre, patient and outcome-assessor blinded, randomized-controlled trial, in which patients scheduled for CRT were randomized to empiric (n = 93) or imaging-guided left-ventricular lead placement (n = 89). All patients underwent clinical evaluation and blood sampling at baseline and 6 months following CRT implantation. The proportion of patients meeting the indication for sacubitril/valsartan (irrespective of angiotensin-converting enzyme inhibitor or angiotensin 2 receptor blocker dosage) and/or ivabradine according to current guidelines was evaluated at baseline and after 6 months. RESULTS: Of 182 patients with an indication for CRT, 146 (80%) also had an indication for optimization of medical therapy at baseline by adding sacubitril/valsartan, ivabradine, or both. Of the 179 survivors at 6 months, 136 (76%) were still symptomatic after device implantation; of these, 51 (38%) patients had an indication for optimization of medical therapy: sacubitril/valsartan in 37 (27%), ivabradine in 7 (5%), and both drugs in 7 (5%) patients. Seven (18%) patients without indication at baseline developed an indication for medical optimization 6 months after CRT implantation. CONCLUSION: In the present study, 38% of those who remained symptomatic 6 months after CRT implantation were eligible for optimization of medical therapy with sacubitril/valsartan, ivabradine, or both. Patients with CRT may benefit from systematic follow-up including evaluation of medical treatment.