Poor long-term prognosis in patients admitted with strong suspicion of acute myocardial infarction but discharged with another diagnosis.

BACKGROUND: Characteristics and prognosis of patients admitted with strong suspicion of myocardial infarction (MI) but discharged without an MI diagnosis are not well-described. OBJECTIVES: To compare background characteristics and cardiovascular outcomes in patients discharged with or without MI diagnosis. METHODS: The DETermination of the role of Oxygen in suspected Acute Myocardial Infarction (DETO2X-AMI) trial compared 6629 patients with strong suspicion of MI randomized to oxygen or ambient air. The main composite end-point of this subgroup analysis was the incidence of all-cause death, rehospitalization with MI, heart failure (HF) or stroke during a follow-up of 2.1 years (median; range: 1-3.7 years) irrespective of randomized treatment. RESULTS: 1619 (24%) received a non-MI discharge diagnosis, and 5010 patients (76%) were diagnosed with MI. Groups were similar in age, but non-MI patients were more commonly female and had more comorbidities. At thirty days, the incidence of the composite end-point was 2.8% (45 of 1619) in non-MI patients, compared to 5.0% (250 of 5010) in MI patients with lower incidences in all individual end-points. However, for the long-term follow-up, the incidence of the composite end-point increased in the non-MI patients to 17.7% (286 of 1619) as compared to 16.0% (804 of 5010) in MI patients, mainly driven by a higher incidence of all-cause death, stroke and HF. CONCLUSIONS: Patients admitted with a strong suspicion of MI but discharged with another diagnosis had more favourable outcomes in the short-term perspective, but from one year onwards, cardiovascular outcomes and death deteriorated to a worse long-term prognosis.

Long term outcome after treatment of de novo coronary artery lesions using three different drug coated balloons.

OBJECTIVE: To evaluate the long-term efficacy of three currently available drug coated balloons (DCB) for the treatment of de-novo coronary lesions. METHODS: This was a retrospective analysis of prospectively collected data from the Swedish Coronary Angiography and Angioplasty Registry. Between 2009 and 2017, three currently available DCB brands used in the treatment of de novo lesions were included. Outcomes were clinically driven restenosis and target lesion thrombosis (TLT) (per device) and major adverse cardiac events (MACE) including death, myocardial infarction or target vessel revascularization (per patient) at 4 years. Multivariable Cox regression models were used to adjust for differences. RESULTS: We included 6715 lesions treated with DCBs, 4483 SeQuent® Please (S-DCB), 1071 IN.PACT Falcon (I-DCB) and 1161 Pantera® Lux (P-DCB), in 5670 patients. The mean DCB diameter was 2.4 mm. Bailout stenting occurred in 6.7% of lesions. Angiographic success was 98.5%. The overall cumulative rate of restenosis was 5.5% (299 events). The risk for reported restenosis did not significantly differ between I-DCB vs S-DCB, adjusted hazard ratio (aHR) 0.96; 95% confidence interval (CI) 0.69-1.34, P-DCB vs S-DCB aHR 0.88; 95% CI 0.63-1.23 and I-DCB vs P-DCB aHR 1.10; 95% CI 0.72-1.68. The cumulative risk for TLT was 0.8% in all three DCBs. The risk for MACE or individual components of MACE did not differ between the three patient-groups. CONCLUSION: In de novo coronary lesions, we found comparable long-term efficacy with three currently available DCB brands. DCB angioplasty was feasible with low risk for long-term restenosis and TLT.

The association of mode of location activity and mobility with acute coronary syndrome: a nationwide ecological study.

BACKGROUND: We aimed to study the effect of social containment mandates on ACS presentation during COVID-19 pandemic using location activity and mobility data from mobile phone map services. METHODS: We conducted a cross-sectional study using data from the Swedish Coronary Angiography and Angioplasty Registry (SCAAR) including all ACS presentations during the pandemic until 7 May 2020. Using a count regression model, we adjusted for day of the week, daily weather and incidence of COVID-19. RESULTS: A 10% increase in activity around areas of residence was associated with 38% lower rates of ACS hospitalizations, whereas increased activity relating to retail and recreation, grocery stores and pharmacies, workplaces and mode of mobility was associated with 10-20% higher rates of ACS hospitalizations. CONCLUSION: Government policy regarding social containment mandates has important public health implications for medical emergencies such as ACS and may explain the decline in ACS presentations observed during COVID-19 pandemic.

Sex-related response to bivalirudin and unfractionated heparin in patients with acute myocardial infarction undergoing percutaneous coronary intervention: A subgroup analysis of the VALIDATE-SWEDEHEART trial.

AIMS: Our aim was to study the impact of sex on anticoagulant treatment outcomes during percutaneous coronary intervention in acute myocardial infarction patients. METHODS: This study was a prespecified analysis of the Bivalirudin versus Heparin in ST-Segment and Non ST-Segment Elevation Myocardial Infarction in Patients on Modern Antiplatelet Therapy in the Swedish Web System for Enhancement and Development of Evidence-based Care in Heart Disease Evaluated according to Recommended Therapies Registry Trial (VALIDATE-SWEDEHEART) trial, in which patients with myocardial infarction were randomised to bivalirudin or unfractionated heparin during percutaneous coronary intervention. The primary outcome was the composite of death, myocardial infarction or major bleeding at 180 days. RESULTS: There was a lower risk of the primary outcome in women assigned to bivalirudin than to unfractionated heparin (13.6% vs 17.1%, hazard ratio 0.78, 95% confidence interval (0.60-1.00)) with no significant difference in men (11.8% vs 11.2%, hazard ratio 1.06 (0.89-1.26), p for interaction 0.05). The observed difference was primarily due to lower risk of major bleeding (Bleeding Academic Research Consortium definition 2, 3 or 5) associated with bivalirudin in women (8.9% vs 11.8%, hazard ratio 0.74 (0.54-1.01)) but not in men (8.5% vs 7.3%, hazard ratio 1.16 (0.94-1.43) in men, p for interaction 0.02). Conversely, no significant difference in the risk of Bleeding Academic Research Consortium 3 or 5 bleeding, associated with bivalirudin, was found in women 4.5% vs 5.4% (hazard ratio 0.84 (0.54-1.31)) or men 2.9% vs 2.1% (hazard ratio 1.36 (0.93-1.99)). Bleeding Academic Research Consortium 2 bleeding occurred significantly less often in women assigned to bivalirudin than to unfractionated heparin. The risk of death or myocardial infarction did not significantly differ between randomised treatments in men or women. CONCLUSION: In women, bivalirudin was associated with a lower risk of adverse outcomes, compared to unfractionated heparin, primarily due to a significant reduction in Bleeding Academic Research Consortium 2 bleeds.

Takotsubo syndrome in hemodynamically unstable patients admitted to the intensive care unit - a retrospective study.

INTRODUCTION: Takotsubo syndrome (TS) is an acute cardiac condition that is often triggered by critical illness but that has rarely been studied in the intensive care unit (ICU) setting. The aim of this study was to (i) estimate the incidence of TS in a hemodynamically unstable ICU-population; (ii) identify predictors of TS in this population; (iii) study the impact of TS on prognosis and course of hospitalization. METHODS: Medical records from all patients admitted to our general ICU from 2012 to 2015 were analyzed. TS was defined as having transient regional wall motion abnormalities (RWMA) with a typical pattern not attributable to a history of coronary artery disease or acute coronary syndromes. RESULTS: Out of 6470 patients admitted to the ICU, echocardiography due to hemodynamic instability was performed in 1051 patients; 467 had LV dysfunction and 59 fulfilled TS criteria. Patients with TS had higher SAPS 3 scores on admission than patients with normal LV function. Septic shock, cardiac arrest, cerebral mass lesion, female sex and low pH were independently associated with TS on admission. Patients with TS needed more ICU resources measured by higher NEMS scores and longer ICU-stay. Crude mortality was higher in TS patients (32%) vs the ICU-population (20%, P = 0.020), but there were no differences in a SAPS 3 adjusted analysis. CONCLUSION: TS was not an uncommon cause of LV dysfunction in hemodynamically unstable ICU-patients. Furthermore, TS was associated with a more complex disease. TS is a complication to take in consideration in the critically ill.

Early treatment with isoflurane attenuates left ventricular dysfunction and improves survival in experimental Takotsubo.

BACKGROUND: Takotsubo syndrome (TS) is an acute cardiac condition, often triggered by critical illness, for which no specific treatment exists. Previously, we showed that isoflurane can prevent experimental TS. The aim of this study was to evaluate the potential treatment effects of isoflurane. Our primary hypothesis was that early treatment with isoflurane attenuates left ventricular akinesia in experimental TS. METHOD: In propofol-sedated animals, TS was induced by an intraperitoneal bolus of isoprenaline (50 mg/kg). Animals were randomized to one of six groups (n = 15 in each group), and 1% isoflurane was administered for 90 min in all groups. Isoflurane treatment was started at 0, 10, 30 (early treatment) or 120 (late treatment) minutes after isoprenaline injection. One additional late treatment group received isoflurane 0.5% for 180 min. A control group did not receive isoflurane. Left ventricular (LV) echocardiographic examination was performed at 90 min and 48 h after isoprenaline. Mortality was assessed at 48 h. RESULTS: Median degree of LV akinesia at 90 min was 24% in the control group and 0% in the early treatment groups (P < 0.001). Stroke volume, cardiac output and LV ejection fraction were higher in the early treatment groups vs. controls (P < 0.01). Mortality was lower in the early treatment groups (24%) vs. controls (86%) (P < 0.001). Mortality did not differ between the late treatment groups and controls. CONCLUSION: Early treatment with isoflurane attenuates the LV akinesia and improves survival in experimental TS. Isoflurane sedation in patients at risk of developing Takotsubo syndrome could be a subject for future studies.

Anaesthetic-induced cardioprotection in an experimental model of the Takotsubo syndrome - isoflurane vs. propofol.

BACKGROUND: Takotsubo syndrome (TS) is an acute cardiac condition with a substantial mortality for which no specific treatment is available. We have previously shown that isoflurane attenuates the development of left ventricular (LV) dysfunction in an experimental TS-model. We compared the effects of equi-anaesthetic doses of isoflurane, propofol and ketamine+midazolam on haemodynamics, global and regional LV systolic function and the activation of intracellular metabolic pathways in experimental TS. We hypothesized that cardioprotection in experimental TS is specific for isoflurane. METHODS: Forty-five rats were randomized to isoflurane (0.6 MAC, n = 15), propofol (bolus 200 mg/kg+360 mg/kg/h, n = 15) or ketamine (100 mg/kg)+midazolam (10 mg/kg, n = 15) anaesthesia. Arterial pressure, heart rate and body temperature were continuously measured and arterial blood gas analysis was performed intermittently. TS was induced by intraperitoneal injection of isoprenaline, 50 mg/kg. LV echocardiography was performed 90 min after isoprenaline injection. Apical cardiac tissue was analysed by global discovery proteomics and pathway analysis. RESULTS: Isoprenaline-induced changes in arterial blood pressure, heart rate or body temperature did not differ between groups. LV ejection fraction was higher and extent of LV akinesia was lower with isoflurane, when compared with the propofol and the ketamine+midazolam groups. In this TS-model, the proteomic analysis revealed an up-regulation of pathways involved in inflammation, coagulation, endocytosis and lipid metabolism. This up-regulation was clearly attenuated with isoflurane compared to propofol. CONCLUSION: In an experimental model of TS, isoflurane, but not propofol, exerts a cardioprotective effect. The proteomic analysis suggests that inflammation might be involved in pathogenesis of TS.

The validity of self-rating depression scales in patients with chronic widespread pain: a Rasch analysis of the Major Depression Inventory.

BACKGROUND: Assessment of depression in chronic pain patients by self-rating questionnaires developed and validated for use in normal and/or psychiatric populations is common. The aim of this study was to evaluate the psychometric properties of the Major Depression Inventory (MDI) in a sample of females with chronic widespread pain (CWP). METHOD: A total of 263 females diagnosed with CWP and referred for rehabilitation completed the MDI as part of the baseline evaluation. Rasch analysis was applied to this dataset. Rasch measurement models allow detailed analyses of an instrument's rating scale and further aspects of validity, including fit of individual scale items to a unidimensional model indicating assessment of a single construct (depression), as a prerequisite for measurement. RESULTS: The Rasch analysis revealed substantial problems with the rating scale properties of the MDI and lack of unidimensionality. In contrast to somatic items, MDI items related to depressed mood and negative view of oneself were distributed at the higher end of the item difficulty measurement scale, indicating low endorsement of these items. DISCUSSION: From the perspective of the Rasch measurement model, the MDI demonstrated insufficient psychometric properties when used to identify and quantify severity of depression in a clinical sample of females with CWP. The observed item endorsement pattern indicated that, in this study population, the relatively high depression severity scores primarily pertained to a common core of pain-related somatic symptoms. Careful consideration when interpreting questionnaire-derived scores of depression implemented in research and routine clinical care of patients with chronic pain is warranted.

17-year trends in incidence and prognosis of cardiogenic shock in patients with acute myocardial infarction in western Sweden.

BACKGROUND: Cardiogenic shock remains the leading cause of in hospital death in acute myocardial infarction (AMI) and is associated with a mortality rate of approximately 50%. Here we investigated the 17-year trends in incidence and prognosis of AMI-induced cardiogenic shock in Västra Götaland in western Sweden, an area with approximately 1.6 million inhabitants. The study period includes the transition from thrombolysis to primary percutaneous coronary intervention (PCI) as the region-wide therapy of choice for patients with ST-elevation myocardial infarction (STEMI). METHODS: Data on patients hospitalized in cardiac care units in Västra Götaland, Sweden between 1995 and 2013 were obtained from the Swedish Websystem for Enhancement of Evidence-based Care in Heart Disease Evaluated According to Recommended Therapies (SWEDEHEART). We determined the incidence of cardiogenic shock among patients diagnosed with AMI and the risk of death associated with developing cardiogenic shock. We fitted logistic regression models to study which factors predicted post-AMI cardiogenic shock. Analyses were performed on complete case data as well as after multiple imputation of missing data. RESULTS: Incidence of cardiogenic shock as a complication of AMI declined in western Sweden in the past decade, from 14% in 1995 to 4% in 2012. The risk of dying once cardiogenic shock had developed increased during the study period (p<0.01). Patients presenting with STEMI were more likely to develop cardiogenic shock than patients presenting with non STEMI (p<0.001). CONCLUSIONS: The incidence of cardiogenic shock has declined but cardiogenic shock carries a worse prognosis today than in 1995.

High-Sensitive Troponin T and N-Terminal Pro B-Type Natriuretic Peptide for Early Detection of Stress-Induced Cardiomyopathy in Patients with Subarachnoid Hemorrhage.

BACKGROUND: Patients developing stress-induced cardiomyopathy (SIC) after subarachnoid hemorrhage (SAH) have increased risk of vasospasm, delayed cerebral ischemia and death. We evaluated whether high-sensitive troponin T (hsTnT) and N-terminal pro B-type natriuretic peptide (NTproBNP) are useful biomarkers for early detection of SIC after SAH. METHODS: Medical records of all patients admitted to our NICU with suspected or verified SAH from January 2010 to August 2014 were reviewed. Patients in whom echocardiography was performed and blood samples for measurements of hsTnT and/or NTproBNP were obtained, within 72 and 48 h, respectively, after onset of symptoms, were included. SIC was defined as reversible left ventricular segmental hypokinesia diagnosed by echocardiography. RESULTS: A total of 502 SAH patients were admitted during the study period, 112 patients fulfilled inclusion criteria and 25 patients fulfilled SIC criteria. Peak levels of hsTnT and NTproBNP were higher in patients with SIC (p < 0.001). hsTnT had its peak on admission, while NTproBNP peaked at days 2-4 after onset of symptoms. A hsTnT > 89 ng/l or a NTproBNP > 2,615 ng/l obtained within 48 h after onset of symptoms had a sensitivity of 100% and a specificity of 79% in detecting SIC. CONCLUSIONS: The cardiac biomarkers, hsTnT and NTproBNP, are increased early after SAH and levels are considerably higher in patients with SIC. These biomarkers are useful for screening of SIC, which could make earlier diagnosis and treatment of SIC in SAH patients possible.

Importance of circulating IGF-1 for normal cardiac morphology, function and post infarction remodeling.

IGF-1 plays an important role in cardiovascular homeostasis, and plasma levels of IGF-1 correlate inversely with systolic function in heart failure. It is not known to what extent circulating IGF-1 secreted by the liver and local autocrine/paracrine IGF-1 expressed in the myocardium contribute to these beneficial effects on cardiac function and morphology. In the present study, we used a mouse model of liver-specific inducible deletion of the IGF-1 gene (LI-IGF-1 -/- mouse) in an attempt to evaluate the importance of circulating IGF-I on cardiac morphology and function under normal and pathological conditions, with an emphasis on its regulatory role in myocardial phosphocreatine metabolism. Echocardiography was performed in LI-IGF-1 -/- and control mice at rest and during dobutamine stress, both at baseline and post myocardial infarction (MI). High-energy phosphate metabolites were compared between LI-IGF-1 -/- and control mice at 4 weeks post MI. We found that LI-IGF-1 -/- mice had significantly greater left ventricular dimensions at baseline and showed a greater relative increase in cardiac dimensions, as well as deterioration of cardiac function, post MI. Myocardial creatine content was 17.9% lower in LI-IGF-1 -/- mice, whereas there was no detectable difference in high-energy nucleotides. These findings indicate an important role of circulating IGF-1 in preserving cardiac structure and function both in physiological settings and post MI.

Effects of complete heart block on myocardial function, morphology, and energy metabolism in the rat.

AIMS: Severe sustained bradycardia may cause acute and possibly chronic congestive heart failure (CHF). The aim of this study was to investigate acute and chronic effects of complete heart block (CHB) on cardiac function, morphology, and creatine (Cr) metabolism. METHODS AND RESULTS: CHB was induced in male Sprague-Dawley rats (approximately 250 g, n = 11) by means of electrocautery applied to the region of AV node and were compared with controls (n = 15). The rats were investigated at 1, 3, and 12 weeks after CHB induction with transthoracic echocardiography. Invasive haemodynamic assessment of left and right ventricular pressures was performed at 12 weeks. After the sacrifice, the hearts were freeze-clamped for analysis of myocardial Cr, and high energy phosphometabolites. The efficacy of operative procedure was 54%. The peri-operative mortality rate was 20%. Heart rate (HR) decreased by approximately 50% (P < 0.01) while stroke volume (SV) increased 2.5 times (P < 0.01) in the CHB rats. Cardiac index remained unchanged. The rats with CHB grew normally and were in no apparent distress. Filling pressures in left and right ventricles were normal. The CHB rats developed marked cardiomegaly with biventricular dilatation and eccentric left ventricular hypertrophy (P < 0.01). There was no change in the myocardial content of Cr and high energy phosphometabolites. CONCLUSION: Rats with CHB are compensating for reduction in HR with increased SV without haemodynamic and biochemical characteristics of CHF. This model may be useful to study the effects of CHB and bradycardia on myocardial structure, function, electrophysiology, and metabolism as well as for studies of cell therapy for reparation of AV conductance.

In vivo MR imaging of magnetically labeled human embryonic stem cells.

INTRODUCTION: Human embryonic stem cells (hES) have emerged as a potentially new therapeutic approach for treatment of heart and other diseases applying the concept of regenerative medicine. A method for in vivo visualization and tracking of transplanted hES would increase our understanding of in vivo hES behavior in both experimental and clinical settings. The aim of this study was to evaluate the feasibility of magnetic labeling and visualization of hES with magnetic resonance imaging (MRI). METHODS: hES were established and expanded according to standard procedures. After expansion, the cells were cultured under feeder free conditions and magnetically labeled by addition of dextran-coated Ferrum-oxide particles (Endorem) to the medium. Accumulation of small particles of iron-oxide (SPIO) in hES was assessed by Prussian blue staining and electron microscopy. For in vitro MRI, the labeled and unlabeled hES were examined in cell solution and after transplantation into explanted mouse heart ( approximately 100,000 cells) on a Bruker Avance DMX 500 vertical magnet at 11.75 T. A multi-slice, multi spin-echo T(2)-weighted images were obtained. For in vivo imaging, the experiments were performed on male Sprague-Dawley using Bruker Biospec 2.35 T magnet. The hES were directly injected ( approximately 500,000 cells) after surgical procedure (thoracotomy) into anterior left ventricular (LV) wall. Multi-slice T(2)-weighted gradient echo images were obtained using cardiac gating. RESULTS: hES appeared to be unaffected by magnetic labeling and maintained their ability to proliferate and differentiate. No additive agent for membrane permeabilisation was needed for facilitation of intracellular SPIO accumulation. Prussian blue and electron microscopy have revealed numerous iron particles in the cytoplasm of hES. On T(2)-weighted images, the labeled cells have shown well-defined hyopintense areas at the site of injection in anterior LV wall both in vitro and in vivo. CONCLUSIONS: It is feasible to magnetically label and visualize hES both in vitro and in vivo. MR visualization of magnetically labeled hES may be a valuable tool for in vivo tracking of hES.

Selective cerebral overexpression of growth hormone alters cardiac function, morphology, energy metabolism and catecholamines in transgenic mice.

BACKGROUND: Growth hormone (GH) has important regulatory effects on cardiac morphology and function both during normal development as well as in pathophysiological settings such as myocardial infarction (MI) and congestive heart failure (CHF). In order to investigate in more detail the interaction between GH and sympathetic nervous system (SNS) system we studied the effects of selective cerebral GH overexpression on myocardial content of catecholamines, myocardial and brain energy metabolism as well as on cardiac function during resting and stress conditions in a transgenic mouse model. METHODS: Transgenic mice with selective bovine GH overexpression under control of glial fibrillary acidic protein promoter in the brain (GFAP-bGH, n=15) were created and compared to genetically matched non-transgenic mates (Control, n=15). Cardiac morphology and function were evaluated in vivo using transthoracic echocardiography during resting and stress conditions induced pharmacologically by dopamine (D) and isoprotenolol (ISO). Myocardial and brain energy metabolism were evaluated non-invasively using in vivo volume-selective phosphorus magnetic resonance spectroscopy ((31)P MRS). Myocardial content of catecholamines was analyzed by means of HPLC. RESULTS: Compared to the C animals, the GFAP-bGH mice have showed several differences in the cardiac phenotype. Systolic (fractional shortening) and diastolic function (E/A wave ratio of mitral flow) was disturbed in the GFAP-bGH mice (both p<0.05). During the dopamine stress, there was chronotropic insufficiency in the GFAP-bGH group (p<0.01) while no difference was observed in response to isoprotenolol. Left ventricular dimensions were increased in GFAP-bGH mice (p<0.05). There was a tendency for higher body weight in GFAP-bGH compared to the control group (p=0.06) while no difference was observed in heart weight and brain weight when normalized for body weight. Myocardial content of noradrenaline was lower in the GFAP-bGH group (p<0.05). PCr/ATP ratio was higher (p<0.05) in the brain and lower in the heart (p<0.05) in the GFAP-bGH mice. CONCLUSIONS: Selective cerebral overexpression of GH results in alterations of cardiac function, morphology and metabolism in transgenic mice. Decreased myocardial content of catecholamines in the GFAP-bGH mice suggests central interaction between GH and sympathetic nervous system.

Selective beta1-blockade attenuates post-infarct remodelling without improvement in myocardial energy metabolism and function in rats with heart failure.

OBJECTIVE: To investigate in vivo effects of long-term selective beta1-blockade on cardiac energy metabolism, remodelling, function and plasma cytokines in a rat model of post-infarct congestive heart failure (CHF). METHODS: Myocardial infarction (MI) was induced in male rats by ligation of the left coronary artery. Three different groups of rats were studied, MI rats treated with metoprolol (n=17), MI rats treated with saline (n=14) and sham-operated rats (n=12). The treatment with metoprolol 1 mg/kg/h was initiated in the third week post-infarct for a period of 6 weeks. All rats were investigated non-invasively with volume-selective 31P magnetic resonance spectroscopy and echocardiography for evaluation of left ventricular (LV) energy metabolism, morphology and function. Plasma concentration of IL-1beta and IL-6 and density of beta-adrenergic receptors were analyzed. RESULTS: Metoprolol attenuated the increase in LV dimensions and volumes. Treatment with metoprolol had no effect on PCr/ATP and LV function. Plasma level of IL-1beta was higher and IL-6 was lower in the metoprolol group. Density of beta-adrenergic receptors was similar in all three groups. CONCLUSION: Selective beta1-blockade in rats with chronic CHF attenuates post-infarct structural remodelling, without concomitant improvement in myocardial energy metabolism and function. Improvements in myocardial energy metabolism and function do not precede and are not a prerequisite for an anti-remodelling effect of beta1-blockade in the setting of chronic CHF.

Growth hormone alone or combined with metoprolol preserves cardiac function after myocardial infarction in rats.

BACKGROUND AND OBJECTIVE: Beta-adrenoreceptor blocking agents are important for the treatment of myocardial infarction (MI). Accumulating evidence also indicates that growth hormone (GH) improves cardiac function after MI in rats. We aimed to investigate the cardiovascular effects of combined treatment in an animal model of MI. METHODS: MI was induced in rats by ligation of the left coronary artery. Three days after MI, animals were randomly assigned to one of four groups: controls (C) (n=19); GH (n=19) receiving s.c. 2 mg/kg per day rhGH; metoprolol (M) group (n=19) receiving 24 mg/kg per day and combined group (GHM) (n=20) treated with both GH (2 mg/kg per day s.c.) and M (24 mg/kg per day) for 9 days. Transthoracic echocardiography was performed before and after treatment. RESULTS: Serum levels of insulin-like growth factor I were significantly elevated in the GH-group but not in the GHM group compared to controls. Left ventricular volumes, cardiac index, systolic blood pressure, were similar in all groups. Percent changes in ejection fraction compared to baseline were; GH (6.1+/-5.0%) and GHM (6.1+/-4.2%) vs. C (-12.5+/-3.0%), P<0.01, M (-7.3+/-4.2%). The occurrence of aneurysms was not significantly different between the various treatment regimes. CONCLUSION: Treatment with growth hormone alone or in combination with metoprolol preserved left ventricular function after MI.

Selective beta(1)-blockade improves cardiac bioenergetics and function and decreases neuroendocrine activation in rats during early postinfarct remodeling.

In spite of the solid evidence that beta-blockade reduces mortality and morbidity in congestive heart failure (CHF) this therapy continues to be underused in clinical praxis. The reason for this may lie in scarcity of knowledge about the mechanisms of beta-blockade action. The major aim of this study was to investigate in vivo whether selective beta(1)-blockade may improve cardiac energy metabolism in rats with myocardial infarction in early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague-Dawley rats by ligation of the left coronary artery. Two different groups of rats were studied, rats with MI treated with metoprolol (5 mg/kg/h; n = 9) and rats with MI saline treated (n = 9). The treatment with metoprolol was given by subcutaneously implanted minipumps and was initiated at 3 days postinfarct and during the period of 4 weeks. All rats were investigated with noninvasive methods (31)P magnetic resonance spectroscopy (MRS) and transthoracic echocardiography 3 days after induction of MI and 4 weeks later. Phosphocreatine/ATP ratio was normalized after the treatment with metoprolol while it was 50% lower in the saline group (p < 0.001). In the metoprolol group stroke volume and ejection fraction increased while deceleration time of mitral early filling was longer (all p < 0.05). Left ventricular weight as well as volumes and dimensions were similar between the groups. Plasma levels of noradrenaline (p = 0.058), adrenaline (p < 0.01) and brain natriuretic peptide (p = 0.09) were lower in the metoprolol group. Selective beta(1)-blockade with high dose of metoprolol initiated in the early postinfarct phase improves myocardial energy metabolism and function and prevents overactivation of sympathetic system. The beneficial effect on myocardial bioenergetics may be an important mode of action of beta-blockers which contributes to the clinical benefits of the therapy in CHF.

Growth hormone improves bioenergetics and decreases catecholamines in postinfarct rat hearts.

The aims of this study were to examine, in vivo, the effects of GH treatment on myocardial energy metabolism, function, morphology, and neurohormonal status in rats during the early postinfarct remodeling phase. Myocardial infarction (MI) was induced in male Sprague Dawley rats. Three different groups were studied: MI rats treated with saline (n = 7), MI rats treated with GH (MI + GH; n = 11; 3 mg/kg x day), and sham-operated rats (sham; n = 8). All rats were investigated with 31P magnetic resonance spectroscopy and echocardiography at 3 days after MI and 3 weeks later. After 3 weeks treatment with GH, the phosphocreatine/ATP ratio increased significantly, compared with the control group (MI = 1.69 +/- 0.09 vs. MI + GH = 2.42 +/- 0.05, P < 0.001; sham = 2.34 +/- 0.08). Treatment with GH significantly attenuated an increase in left ventricular end systolic volume and end diastolic volume. A decrease in ejection fraction was prevented in GH-treated rats (P < 0.05 vs. MI). Myocardial and plasma noradrenaline levels were significantly lower in MI rats treated with GH. These effects were accompanied by normalization of plasma brain natriuretic peptide levels (sham = 124.1 +/- 8.4; MI = 203.9 +/- 34.7; MI + GH = 118.3 +/- 8.4 ng/ml; P < 0.05 vs. MI). In conclusion, GH improves myocardial energy reserve, preserves left ventricular function, and attenuates pathologic postinfarct remodeling in the absence of induction of left ventricular hypertrophy in postinfarct rats. The marked decrease in myocardial content of noradrenaline, after GH treatment, may protect myocardium from adverse effects of catecholamines during postinfarct remodeling.

Impairment of cardiac function and bioenergetics in adult transgenic mice overexpressing the bovine growth hormone gene.

Cardiovascular abnormalities represent the major cause of death in patients with acromegaly. We evaluated cardiac structure, function, and energy status in adult transgenic mice overexpressing bovine GH (bGH) gene. Female transgenic mice expressing bGH gene (n = 11) 8 months old and aged matched controls (n = 11) were used. They were studied with two-dimensional guided M-mode and Doppler echocardiography. The animals (n = 6) for each group were examined with 31P magnetic resonance spectroscopy to determine the cardiac energy status. Transgenic mice had a significantly higher body weight (BW), 53.2+/-2.4 vs. 34.6+/-3.7 g (P < 0.0001) and hypertrophy of left ventricle (LV) compared with normal controls: LV mass/BW 5.6+/-1.6 vs. 2.7+/-0.2 mg/g, P < 0.01. Several indexes of systolic function were depressed in transgenic animals compared with controls mice such as shortening fraction 25+/-3.0% vs. 39.9+/-3.1%; ejection fraction, 57+/-9 vs. 77+/-5; mean velocity of circumferential shortening, 4.5+/-0.8 vs. 7.0+/-1.1 circ/sec, p < 0.01. Creatine phosphate-to-ATP ratio was significantly lower in bGH overexpressing mice (1.3+/-0.08 vs. 2.1+/-0.23 in controls, P < 0.05). Ultrastructural examination of the hearts from transgenic mice revealed substantial changes of mitochondria. This study provides new insight into possible mechanisms behind the deteriorating effects of long exposure to high level of GH on heart function.

In vivo metabolic imaging of cardiac bioenergetics in transgenic mice.

Recent advances in transgenic technology have made the mouse a particularly interesting small animal in cardiovascular research. Increasingly sophisticated experimental methods and tools are needed for detailed characterization of cardiovascular physiology and biochemistry in the mice. The objective of this study was to develop a method for noninvasive evaluation of cardiac energy metabolism in the mouse. Cardiac gated (31)P magnetic resonance spectroscopy using Image Selected in Vivo Spectroscopy (ISIS) method was applied in old mice overexpressing bovine growth hormone (bGH) (n = 5) and control mice (n = 5). The localized volumes of interest were 128 and 112 microL, respectively. Phosphocreatine-to-ATP ratio was 1.5 +/- 0.13 in the bGH mice and 2.1 +/- 0.04 in the control group (P < 0.01). The study demonstrates the feasibility of application of volume-selective (31)P MRS for evaluation of cardiac energy metabolism in the mouse under maintained physiological conditions.