The Effects of Octreotide in Dilated Cardiomyopathy: An Open-label Trial in 12 Patients

Gut Hormones in Heart Failure

Heart failure (HF) is a syndrome affecting all organ systems. While some organ interactions have been studied intensively in HF (such as the cardiorenal interaction), the endocrine gut has to some degree been overlooked. However, there is growing evidence of direct cardiac effects of several hormones secreted from the gastrointestinal tract. For instance, GLP-1 (glucagon-like peptide-1), an incretin hormone secreted from the distal intestine following food intake, has notable effects on the heart, impacting heart rate and contractility. GLP-1 may even possess cardioprotective abilities, such as inhibition of myocardial ischemia and cardiac remodeling. While other gut hormones have been less studied, there is evidence suggesting cardiostimulatory properties of several hormones. Moreover, it has been reported that patients with HF have altered bioavailability of numerous gastrointestinal hormones, which may have prognostic implications. This might indicate an important role of gut hormones in cardiac physiology and pathology, which may be of particular importance in the failing heart. We present an overview of the current knowledge on gut hormones in HF, focusing on HF with reduced ejection fraction, and discuss how these hormones may be regulators of cardiac function and central hemodynamics. Potential therapeutic perspectives are discussed, and knowledge gaps are highlighted herein.

Somatostatin Receptor Type 2 as a Potential Marker of Local Myocardial Inflammation in Myocardial Infarction: Morphologic Data on Distribution in Infarcted and Normal Human Myocardium

Nuclear imaging modalities can detect somatostatin receptor type 2 (SSTR2) in vivo as a potential marker of local post-MI inflammation. SSTR2+ macrophages are thought to be the main substrate for SSTR-targeted radioimaging. However, the distribution of SSTR2+ cells in the MI patients' myocardium is unknown. Using immunohistochemistry, we investigated the distribution of SSTR2+ cells in the myocardium of patients who died during the MI inflammatory phase (n = 7) compared to the control group of individuals with fatal trauma (n = 3). Inflammatory cellular landscapes evolve in a wave front-like pattern, so we divided the myocardium into histological zones: the infarct core (IC), the border zone (BZ), the remote zone (RZ), and the peri-scar zone (PSZ). The number of SSTR2+ neutrophils (NPs), SSTR2+ monocytes/macrophages (Mos/MPs), and SSTR2+ vessels were counted. In the myocardium of the control group, SSTR2+ NPs and SSTR2+ Mos/MPs were occasional, SSTR2+ vessels were absent. In the RZ, the picture was similar to the control group, but there was a lower number of SSTR2+ Mos/MPs in the RZ. In the PSZ, SSTR2+ vessel numbers were highest in the myocardium. In the IC, the median number of SSTR2+ NPs was 200 times higher compared to the RZ or control group myocardium, which may explain the selective uptake of SSTR-targeted radiotracers in the MI area during the inflammatory phase of MI.

Somatostatin and Its Receptors in Myocardial Ischemia/Reperfusion Injury and Cardioprotection

Little is known about the role of the neuropeptide somatostatin (SST) in myocardial ischemia/reperfusion injury and cardioprotection. Here, we investigated the direct cardiocytoprotective effect of SST on ischemia/reperfusion injury in cardiomyocyte cultures, as well as the expression of SST and its receptors in pig and human heart tissues. SST induced a bell-shaped, concentration-dependent cardiocytoprotection in both adult rat primary cardiomyocytes and H9C2 cells subjected to simulated ischemia/reperfusion injury. Furthermore, in a translational porcine closed-chest acute myocardial infarction model, ischemic preconditioning increased plasma SST-like immunoreactivity. Interestingly, SST expression was detectable at the protein, but not at the mRNA level in the pig left ventricles. SSTR1 and SSTR2, but not the other SST receptors, were detectable at the mRNA level by PCR and sequencing in the pig left ventricle. Moreover, remote ischemic conditioning upregulated SSTR1 mRNA. Similarly, SST expression was also detectable in healthy human interventricular septum samples at the protein level. Furthermore, SST-like immunoreactivity decreased in interventricular septum samples of patients with ischemic cardiomyopathy. SSTR1, SSTR2, and SSTR5 but not SST and the other SST receptors were detectable at the mRNA level by sequencing in healthy human left ventricles. In addition, in healthy human left ventricle samples, SSTR1 and SSTR2 mRNAs were expressed especially in vascular endothelial and some other cell types as detected by RNA Scope® in situ hybridization. This is the first demonstration that SST exerts a direct cardiocytoprotective effect against simulated ischemia/reperfusion injury. Moreover, SST is expressed in the heart tissue at the peptide level; however, it is likely to be of sensory neural origin since its mRNA is not detectable. SSTR1 and SSTR2 might be involved in the cardioprotective action of SST, but other mechanisms cannot be excluded.

Insights from Second-Line Treatments for Idiopathic Dilated Cardiomyopathy

Background: Dilated cardiomyopathy (DCM) is an independent nosographic entity characterized by left ventricular dilatation and contractile dysfunction leading to heart failure (HF). The idiopathic form of DCM (iDCM) occurs in the absence of coronaropathy or other known causes of DCM. Despite being different from other forms of HF for demographic, clinical, and prognostic features, its current pharmacological treatment does not significantly diverge. Methods: In this study we performed a Pubmed library search for placebo-controlled clinical investigations and a post-hoc analysis recruiting iDCM from 1985 to 2016. We searched for second-line pharmacologic treatments to reconsider drugs for iDCM management and pinpoint pathological mechanisms. Results: We found 33 clinical studies recruiting a total of 3392 patients of various durations and sizes, as well as studies that tested different drug classes (statins, pentoxifylline, inotropes). A metanalysis was unfeasible, although a statistical significance for changes upon treatment for molecular results, morphofunctional parameters, and clinical endpoints was reported. Statins appeared to be beneficial in light of their pleiotropic effects; inotropes might be tolerated more for longer times in iDCM compared to ischemic patients. General anti-inflammatory therapies do not significantly improve outcomes. Metabolic and growth modulation remain appealing fields to be investigated. Conclusions: The evaluation of drug effectiveness based on direct clinical benefit is an inductive method providing evidence-based insights. This backward approach sheds light on putative and underestimated pathologic mechanisms and thus therapeutic targets for iDCM management.

Safety of Subcutaneous Octreotide in Patients with Sulfonylurea-Induced Hypoglycemia and Congestive Heart Failure

Objective:

To report the safe use of subcutaneous octreotide in the treatment of sulfonylurea-induced hypoglycemia in 2 patients with severe congestive heart failure.

Case Summary:

Two patients with congestive heart failure with systolic dysfunction presented with severe hypoglycemia (blood glucose level: patient 1, 31 mg/dL; patient 2, 36 mg/dL) secondary to sulfonylurea agents. The mechanism of hypoglycemia was poor oral intake and prolonged half-life of the drugs due to renal failure. Hypoglycemia was refractory to glucose supplementation. Patient 1 received 2 doses of octreotide 50 μg subcutaneously 12 hours apart, with resolution of hypoglycemia (blood glucose level: <33 mg/dL before administration of octreotide, 62 mg/dL after first dose, 121 mg/dL after second dose). Patient 2 received an initial dose of octreotide 25 μg subcutaneously; hypoglycemia persisted after this dose, and the patient was given 2 doses of 50 μg subcutaneously 12 hours apart, leading to resolution of hypoglycemia (blood glucose level: 57 mg/dL before administration of octreotide, 80 mg/dL after first dose, 85 mg/dL after second dose, 146 mg/dL after third dose). Resolution of hypoglycemia with octreotide treatment obviated the need for prolonged intravenous dextrose infusions. No local or systemic adverse effects, especially cardiac adverse events, were noted during the course of treatment.

Discussion:

Octreotide is considered the antidote for sulfonylurea-induced hypoglycemia. It may be especially useful in patients with congestive heart failure who may not tolerate intravenous infusions of dextrose. The package insert cautions of the occurrence of cardiac adverse effects such as bradycardia, heart block, and worsening heart failure. Patients with heart failure may theoretically be at a higher risk of these adverse effects due to the concurrent use of atrioventricular blocking agents. However, a review of current literature reveals that the adverse effect profile depends on the route, dose, and formulation of the octreotide used along with the clinical indication. These adverse effects may not be clinically significant with the doses used for treatment of sulfonylurea-induced hypoglycemia and the benefits of the drug may outweigh the risks.

Conclusions:

In these cases, octreotide was safely and effectively used in the treatment of sulfonylurea-induced hypoglycemia in patients with congestive heart failure by adhering to dosing guidelines and close monitoring.

The long-term cardiovascular outcome of different GH-lowering treatments in acromegaly

The aim of this longitudinal study was to evaluate the echocardiographic outcome of acromegalic heart disease in patients undergoing different therapeutic approaches, in order to investigate whether SSA could provide therapeutic advantages as compared with neurosurgery. In total of 36, consecutive patients undergoing SSA treatment after neurosurgery were enrolled in this study (Gr.Surg.-SSA). After 12 months of treatment, 21 patients had a controlled disease, while the remaining 15 patients displayed uncontrolled disease. Twelve acromegalic patients who did not undergo SSA treatment due to controlled disease after neurosurgery were enrolled as control group (Gr.Surg). The echocardiographic-Doppler study was performed before neurosurgery and after 12-months of follow-up. After follow-up, a significant reduction in serum GH and IGF-I values, Left Ventricular Mass index (LVMi) and LVH rate with an improvement in diastolic function was observed in both groups of patients. We found a significant reduction of LVMi either in patients with controlled disease or in those with poorly controlled disease undergoing SSA treatment. Diastolic function and of LVH percentage improved in all groups, but significantly so only in controlled patients, no significant difference in any echocardiographic parameters and in the prevalence of the LVH rate were observed between the three groups of patients at the end of follow-up. Therefore, our data appear to show that for echographic parameters medical treatment additive beneficial effects is compared to neurosurgery alone. SSA also appears to contribute to the improvement of acromegalic cardiomyopathy also in patients who did not achieve biochemical control of the disease.

Resolution of acromegalic cardiomyopathy in mild acromegalic physical abnormality after short-term octreotide therapy

Congestive heart failure developed in a 42-year-old man who had very mild acromegalic features. Echocardiography showed a marked dilatation of the left ventricle and decreased systolic function. Laboratory examinations revealed the elevated levels of growth hormone and insulin-like growth factor-1 and pituitary microadenoma was demonstrated by magnetic resonance imaging. Although the extensive conventional medical treatment was ineffective, short-term addition of somatostatin analog, octreotide, rapidly improved his cardiac function. After discontinuation of octreotide, further improvement was observed with minimal residual diastolic dysfunction. All medical treatment could be stopped after successful trans-sphenoidal surgery. Early diagnosis and effective treatment is important to reverse the acromegalic cardiomyopathy.