GIP receptor antagonism eliminates paradoxical growth hormone secretion in some patients with acromegaly.

CONTEXT: About 30% of patients with active acromegaly experience paradoxically increased growth hormone (GH) secretion during the diagnostic oral glucose tolerance test (OGTT). Endogenous glucose-dependent insulinotropic polypeptide (GIP) is implicated in this paradoxical secretion. OBJECTIVE: We used the GIP receptor (GIPR) antagonist GIP(3-30)NH2 to test the hypothesis that GIP mediates this paradoxical response when GIPR is abundantly expressed in somatotropinomas. DESIGN, PATIENTS, SETTING, INTERVENTIONS: 25 treatment-naïve patients with acromegaly were enrolled. Each patient underwent one OGTT during simultaneous placebo infusion and one OGTT during a GIP(3-30)NH2 infusion. Blood samples were drawn at baseline and regularly after infusions to measure GH. We assessed pituitary adenoma size by magnetic resonance imaging and GIPR expression by immunohistochemistry on resected somatotropinomas. For mechanistic confirmation, we applied in vitro and ex vivo approaches. MAIN OUTCOME MEASURE: The effect of GIP(3-30)NH2 on paradoxical GH secretion during OGTT as a measure of GIP involvement. RESULTS: In four of seven patients with paradoxical GH secretion, GIP(3-30)NH2 infusion completely abolished the paradoxical response (P = 0.0003). Somatotrophs were available from three of four of these patients, all showing abundant GIPR expression. Adenoma size did not differ between patients with and without paradoxical GH secretion. CONCLUSIONS: Of 25 patients with acromegaly, seven had paradoxical GH secretion during OGTT, and pharmaceutical GIPR blockade abolished this secretion in four. Corresponding somatotroph adenomas abundantly expressed GIPR, suggesting a therapeutic target in this subpopulation of patients. In vitro and ex vivo analyses confirmed the role of GIP and the effects of the antagonist.

Post-Bariatric Hypoglycemia: an Impaired Metabolic Response to a Meal.

AIMS/HYPOTHESIS: Post-bariatric hypoglycemia (PBH) is caused by postprandial hyperinsulinemia, due to anatomical alterations and changes in post-prandial metabolism after bariatric surgery. The mechanisms underlying the failing regulatory and compensatory systems are unclear. In this study, we investigated the differences in post-prandial hormones and metabolic profiles between patients with and without PBH. METHODS: We performed a mixed meal test (MMT) in 63 subjects before and 1 year after Roux-en-Y gastric bypass (RYGB) surgery. Blood was withdrawn at 0, 10, 20, 30, 60, and 120 min after ingestion of a standardized meal. Glucose, insulin, GLP-1, FGF-19, and FGF-21 were measured and untargeted metabolomics analysis was performed on blood plasma to analyze which hormonal and metabolic systems were altered between patients with and without PBH. RESULTS: Out of 63, a total of 21 subjects (33%) subjects developed PBH (glucose < 3.1 mmol/L) after surgery. Decreased glucose and increased insulin excursions during MMT were seen in PBH (p < 0.05). GLP-1, FGF-19, and FGF-21 were elevated after surgery (p < 0.001), but did not differ between PBH and non-PBH groups. We identified 20 metabolites possibly involved in carbohydrate metabolism which differed between the two groups, including increased carnitine and acylcholines in PBH. CONCLUSION: Overall, 33% of the subjects developed PBH 1 year after RYGB surgery. While GLP-1, FGF-19, and FGF-21 were similar in PBH and non-PBH patients, metabolomics analysis revealed changes in carnitine and acyclcholines that are possibly involved in energy metabolism, which may play a role in the occurrence of PBH.

Randomized Crossover Trial of 2-Week Ketone Ester Treatment in Patients With Type 2 Diabetes and Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a major cause of morbidity and mortality in patients with type 2 diabetes (T2DM). Acute increases in circulating levels of ketone body 3-hydroxybutyrate have beneficial acute hemodynamic effects in patients without T2DM with chronic heart failure with reduced ejection fraction. However, the cardiovascular effects of prolonged oral ketone ester (KE) treatment in patients with T2DM and HFpEF remain unknown. METHODS: A total of 24 patients with T2DM and HFpEF completed a 6-week randomized, double-blind crossover study. All patients received 2 weeks of KE treatment (25 g D-ß-hydroxybutyrate-(R)-1,3-butanediol × 4 daily) and isocaloric and isovolumic placebo, separated by a 2-week washout period. At the end of each treatment period, patients underwent right heart catheterization, echocardiography, and blood samples at trough levels of intervention, and then during a 4-hour resting period after a single dose. A subsequent second dose was administered, followed by an exercise test. The primary end point was cardiac output during the 4-hour rest period. RESULTS: During the 4-hour resting period, circulating 3-hydroxybutyrate levels were 10-fold higher after KE treatment (1010±56 µmol/L; P<0.001) compared with placebo (91±55 µmol/L). Compared with placebo, KE treatment increased cardiac output by 0.2 L/min (95% CI, 0.1 to 0.3) during the 4-hour period and decreased pulmonary capillary wedge pressure at rest by 1 mm Hg (95% CI, -2 to 0) and at peak exercise by 5 mm Hg (95% CI, -9 to -1). KE treatment decreased the pressure-flow relationship (∆ pulmonary capillary wedge pressure/∆ cardiac output) significantly during exercise (P<0.001) and increased stroke volume by 10 mL (95% CI, 0 to 20) at peak exercise. KE right-shifted the left ventricular end-diastolic pressure-volume relationship, suggestive of reduced left ventricular stiffness and improved compliance. Favorable hemodynamic responses of KE treatment were also observed in patients treated with sodium-glucose transporter-2 inhibitors and glucagon-like peptide-1 analogs. CONCLUSIONS: In patients with T2DM and HFpEF, a 2-week oral KE treatment increased cardiac output and reduced cardiac filling pressures and ventricular stiffness. At peak exercise, KE treatment markedly decreased pulmonary capillary wedge pressure and improved pressure-flow relationship. Modulation of circulating ketone levels is a potential new treatment modality for patients with T2DM and HFpEF. REGISTRATION: URL: https://www.clinicaltrials.gov; Unique Identifier: NCT05236335.

Lymphatic morphology and function in chronic right heart failure due to secondary tricuspid valve regurgitation.

BACKGROUND: In heart failure, the capacity of the lymphatic system dictates symptoms of circulatory congestion. This study aimed at describing structural and functional changes of the lymphatic system in patients with chronic right-sided heart failure. METHODS: Individuals with long-standing severe tricuspid valve regurgitation and symptoms of heart failure were compared with age- gender- and weight-matched controls. Lymphatic structure and function were examined using non-contrast MR lymphangiography and near-infrared fluorescence imaging. Microvascular fluid dynamics and distribution were evaluated using strain gauge plethysmography and bio-impedance. RESULTS: In total nine patients and nine controls were included. Lymphatic morphology was unchanged in cases compared to controls with similar thoracic duct diameters 3.1(2.1-3.5) mm vs. 2.0(1.8-2.4) mm (p-value = 0.11), similar lymphatic classifications (p-value 0.34), and an identical number of lymphatic vessels in the legs 6 ± 1 vs. 6 ± 3 vessels/field (p-value = 0.72). Lymphatic function was comparable with contraction frequencies of 0.5 ± 0.2 and 0.5 ± 0.3 /min (p-value = 0.52) and a maximal lymphatic pumping pressure of 60 ± 13 and 57 ± 12 mmHg (p-value = 0.59) for cases and controls respectively. Finally, microvascular capillary filtration, isovolumetric threshold, and fluid distribution were similar between groups (p-value≥0.16 for all comparisons). CONCLUSION: In this small exploratory study, individuals with severe secondary tricuspid valve regurgitation and right-sided heart failure displayed a largely similar lymphatic anatomy and function. Thoracic duct diameter displayed a trend towards increased size in the patient group. We speculate that cases were indeed stable and optimally treated at the time of examination, and with a lymphatic system largely unaffected by any of the current or prior hemodynamic changes.

Exercise Hemodynamics and Mitochondrial Oxidative Capacity in Disease Stages of Wild-Type Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Wild-type transthyretin amyloid (ATTRwt) cardiomyopathy is increasingly recognized in the development of heart failure. The link between cardiac performance, hemodynamics, and mitochondrial function in disease stages of ATTRwt has not previously been studied but may provide new insights into the pathophysiology and clinical performance of the patients. METHODS AND RESULTS: The study investigated 47 patients diagnosed with ATTRwt at Aarhus University Hospital, Denmark. Patients were stratified according to the disease stages of the National Amyloidosis Centre (NAC) as NAC I with low levels of NT-proBNP (N-terminal pro-B-type natriuretic peptide) (NAC I-L, n=14), NAC I with high levels NT-proBNP (NAC I-H, n=20), and NAC II-III (n=13). Exercise testing with simultaneous right heart catheterization was performed in all patients. Endomyocardial biopsies were collected from the patients and the mitochondrial oxidative phosphorylation capacity was assessed. All NAC disease groups, even in the NAC I-L group, a significant abnormal increase in biventricular filling pressures were noted during exercise while the filling pressures was normal or near normal at rest. The inotropic response to exercise was reduced with diminished increase in cardiac output which was significantly more pronounced in the NAC I-H (Diff. -2.4, 95% CI (-4.2: -0.7), P=0.00) and the NAC II-III group (Diff: -3.1 L/min, 95% CI (-5.2: -1.1), P=0.00) compared with the NAC I-L group. The pulmonary artery wedge pressure to cardiac output ratio at peak exercise was significantly different between NAC I-L and NAC II-III (Diff: 1.6 mm Hg*min/L, 95% CI (0.01:3.3, P=0.04)). Patients with ATTRwt had a reduced oxidative phosphorylation capacity which correlated to left ventricular mass but not to cardiac output capacity. CONCLUSIONS: An abnormal restrictive left ventricle and right ventricle response to exercise was demonstrated, even present in patients with early-stage ATTRwt. In more advanced disease stages a progressive impairment of the pressure-flow relationship was noted. The myocyte energetics is deranged but not associated to the contractile reserve or restrictive filling characteristics in ATTRwt.

Familial occurrences of cardiac wild-type transthyretin amyloidosis: a case series.

Background: Cardiomyopathy caused by aggregation and deposition of transthyretin amyloid fibrils in the heart (ATTR-CM) is divided into a hereditary (ATTRv) and a wild-type (ATTRwt) forms. While ATTR-CM has been considered a rare disease, recent studies suggest that it is severely underdiagnosed and an important cause of heart failure in elderly patients. Familial occurrence is implicit in ATTRv, but it is not expected in ATTRwt. Case summary: We report a case series of two unrelated families each with two brothers diagnosed with ATTRwt. Genetic testing did not reveal mutations in the transthyretin gene. Family screening with electrocardiogram, echocardiography, and genetic testing did not raise any suspicion of ATTR in first-line family members. Discussion: Familial occurrence of a rare, non-hereditary disease is statistically unlikely. Two siblings in two different families diagnosed with ATTRwt highlight that the aetiology of ATTRwt is poorly understood, and that genetic factors distinct from mutations in the transthyretin gene, as well as environmental factors, might contribute to the pathogenesis. Identifying such factors might reveal new therapeutic targets. To investigate this further, clinicians need to be aware of the possibility of familial occurrence of ATTRwt.

High incidence of imperforate vagina in ADGRA3-deficient mice.

BACKGROUND: Ten percent of the female population suffers from congenital abnormalities of the vagina, uterus, or oviducts, with severe consequences for reproductive and psychological health. Yet, the underlying causes of most of these malformations remain largely unknown. ADGRA3 (GPR125) is involved in WNT signaling and planar cell polarity, mechanisms vital to female reproductive tract development. Although ADGRA3 is a well-established spermatogonial stem cell marker, its role within the female urogenital system remains unclear. RESULTS: In this study, we found Adgra3 to be expressed throughout the murine female urogenital system, with higher expression pre-puberty than after sexual maturation. We generated a global Adgra3-/- mouse line and observed imperforate vagina in 44% of Adgra3-/- females, resulting in distension of the reproductive tract and infertility. Ovarian morphology, plasma estradiol, ovarian Cyp19a1, and vaginal estrogen receptor α (Esr1) expression were unaffected. However, compared to controls, a significantly lower bone mineral density was found in Adgra3-/- mice. Whereas vaginal opening in mice is an estrogen-dependent process, 17ß-estradiol treatment failed to induce vaginal canalization in Adgra3-/- mice. Furthermore, a marked reduction in vaginal and ovarian progesterone receptor expression was observed concomitant with an upregulation of apoptotic regulators Bcl2, Bid, and Bmf in adult Adgra3-/- females with a closed vagina. CONCLUSIONS: Our collective results shed new insights into the complex mechanisms by which the adhesion receptor ADGRA3 regulates distal vaginal tissue remodeling during vaginal canalization via altered sex hormone responsiveness and balance in apoptotic regulators. This highlights the potential of ADGRA3 as a target in diagnostic screening and/or therapy for obstructive vaginal malformations in humans.

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 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.

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.

High Incidence of Cardiovascular Disease in Patients With Oesophageal Cancer-A Registry-Based Cohort Study.

BACKGROUND: The cardiovascular disease (CVD) burden among patients with oesophageal cancer (EC) treated with curative intent is unclear. AIM: To determine CVD incidence and all-cause mortality in patients with EC. METHOD: Danish national health registries were used to identify patients diagnosed with primary EC between 2008 and 2018. Each EC patient was matched with 10 individuals from the general population. The primary endpoint was a CVD hospital contact (CVD-HC), either admission or outpatient contact. Cox proportional hazard regression models were used to compare the risk of incident CVD-HCs between the cohorts. RESULTS: The study included 1,525 patients with EC and 15,250 individuals from the general population. Patients with EC had a post-diagnosis one-year adjusted hazard ratio (HR) of CVD-HC of 6.1 (95% confidence intervals [CIs] 5.6-6.8) compared with the general population. During the next nine years, the risk of CVD-HC was comparable between the two cohorts, with an adjusted HR of 1.0 (95% CI 0.9-1.3). Patients with EC, and particularly those with prevalent CVD, had a high risk of atrial fibrillation, ischaemic heart disease, and venous thromboembolism within the first year after EC diagnosis. Prevalent CVD among patients with EC was not associated with higher mortality. CONCLUSIONS: CVD morbidity was transiently increased in the first year following EC diagnosis compared with the general population. All-cause mortality risks were high but did not appear to be affected by prevalent CVD. The very high risk of CVD in patients with primary EC to be treated with curative intent calls for healthcare initiatives to advance preventive and post-treatment strategies.

Efficacy and Safety of Acoramidis in Transthyretin Amyloid Cardiomyopathy.

BACKGROUND: Transthyretin amyloid cardiomyopathy is characterized by the deposition of misfolded monomeric transthyretin (TTR) in the heart. Acoramidis is a high-affinity TTR stabilizer that acts to inhibit dissociation of tetrameric TTR and leads to more than 90% stabilization across the dosing interval as measured ex vivo. METHODS: In this phase 3, double-blind trial, we randomly assigned patients with transthyretin amyloid cardiomyopathy in a 2:1 ratio to receive acoramidis hydrochloride at a dose of 800 mg twice daily or matching placebo for 30 months. Efficacy was assessed in the patients who had an estimated glomerular filtration rate of at least 30 ml per minute per 1.73 m2 of body-surface area. The four-step primary hierarchical analysis included death from any cause, cardiovascular-related hospitalization, the change from baseline in the N-terminal pro-B-type natriuretic peptide (NT-proBNP) level, and the change from baseline in the 6-minute walk distance. We used the Finkelstein-Schoenfeld method to compare all potential pairs of patients within strata to generate a P value. Key secondary outcomes were death from any cause, the 6-minute walk distance, the score on the Kansas City Cardiomyopathy Questionnaire-Overall Summary, and the serum TTR level. RESULTS: A total of 632 patients underwent randomization. The primary analysis favored acoramidis over placebo (P<0.001); the corresponding win ratio was 1.8 (95% confidence interval [CI], 1.4 to 2.2), with 63.7% of pairwise comparisons favoring acoramidis and 35.9% favoring placebo. Together, death from any cause and cardiovascular-related hospitalization contributed more than half the wins and losses to the win ratio (58% of all pairwise comparisons); NT-proBNP pairwise comparisons yielded the highest ratio of wins to losses (23.3% vs. 7.0%). The overall incidence of adverse events was similar in the acoramidis group and the placebo group (98.1% and 97.6%, respectively); serious adverse events were reported in 54.6% and 64.9% of the patients. CONCLUSIONS: In patients with transthyretin amyloid cardiomyopathy, the receipt of acoramidis resulted in a significantly better four-step primary hierarchical outcome containing components of mortality, morbidity, and function than placebo. Adverse events were similar in the two groups. (Funded by BridgeBio Pharma; ATTRibute-CM ClinicalTrials.gov number, NCT03860935.).