Left ventricular SGLT1 expression is upregulated in heart failure in humans and rat model

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary;

Ministry of Human Capacities of Hungary

Introduction

Myocardial sodium-glucose cotransporter 1 (SGLT1) has been shown to contribute to cardiac pathological processes, whereas humans with functionally limited SGLT1 are at lower risk of developing heart failure (HF). The novel HF medications, SGLT2 inhibitors, non-selectively inhibit SGLT1 to different extent, therefore, characterization of its expression in disease conditions is relevant.

Purpose

To investigate left ventricular (LV) SGLT1 expression in humans with end-stage HF, and in a rat model of HF.

Methods

Myocardial LV samples were harvested from control subjects (Controls, n=9) undergoing valve surgery, and from patients with end-stage dilated cardiomyopathy (DCM, n=12) undergoing heart transplantation. The rat model of aorto-caval fistula (ACF, n=12) was used to induce HF with predominant LV dilation in rats during a course of 24 weeks; sham-operated animals served as controls (Sham-A, n=12). Echocardiography was used to assess LV structure and function prior to surgery in humans, as well as in rats at the end of the follow-up period. Western blotting was performed to characterize LV SGLT1 protein expression and to investigate the activity of the master regulators AMPK and ERK1/2. The extent of LV nitro-oxidative stress was quantified by immunohistochemistry (3-nitrotyrosine) in rats with HF.

Results

Both humans with DCM and rats with ACF-induced HF presented with severely dilated LVs compared to respective controls, whereas LV SGLT1 protein expression was significantly upregulated similarly by ~1.7-fold in both cases (both P<0.01). These increases in SGLT1 expressions were accompanied by significant reductions in ERK1/2 activating phosphorylation (both P<0.05), whereas AMPK activity was unaffected. In rats with HF, LV SGLT1 expression correlated significantly with the extent of myocardial nitro-oxidative stress (r=0.762, P=0.037).

Conclusions

LV SGLT1 expression is upregulated in HF in both humans and small animals, and ERK1/2 shows a concomitantly reduced activity. LV SGLT1 expression correlates with the extent of nitro-oxidative stress, suggesting a possible pathological role in HF. Whether SGLT2 inhibitors exert direct cardiac actions via inhibition of myocardial SGLT1 needs to be elucidated.

Left ventricular rotational abnormalities in adult patients with corrected tetralogy of Fallot following different surgical procedures – a three-dimensional speckle-tracking echocardiographic study

Introduction

Tetralogy of Fallot (TOF) is the most common cyanotic congenital heart disease. Abnormal aortic dimensions and elasticity parameters have been long described for corrected TOF (cTOF) together with left ventricular (LV) rotational abnormalities. The present study focuses on investigating LV rotational mechanics in cTOF, and possible correlation of these parameters with aortic elastic properties. It was also aimed to be examined whether different surgical strategies has any effect on the results.

Methods

The study involved 26 adult cTOF patients, from which 14 had palliative surgery first [Blaloc-Taussig (n=10), Waterstone-Cooley (n=2) shunts, or Brock procedure (n=2)] (mean age at the repair: 7.3±10.2 years) and a late total correction (mean age at the repair: 10.0±13.3 years) (pcTOF), while the early total correction was the treatment of choice in 12 patients (mean age at the repair: 4.2±3.2 years) (etrTOF). Their results were compared to that of 37 age- and gender-matched healthy adults. Routine transthoracic two-dimensional Doppler echocardiography extended with assessment of aortic elastic properties and three-dimensional speckle-tracking echocardiography (3DSTE) was performed in all cTOF patients and controls.

Results

Sixteen out of 26 cTOF patients showed normally directed LV rotational mechanics, while apical and basal LV rotations were in the same clockwise and counterclockwise directions in 7 and 3 cTOF cases, respectively (38%). This sort of LV movement is called as LV rigid body rotation (RBR). The ratio of LV-RBR between etrTOF and pcTOF patients did not differ significantly (33% vs. 43%, p=0.70). Significantly reduced LV apical rotation (5.2±3.7 degree vs. 10.2±4.5 degree, p<0.05) and twist (9.0±3.3 degree vs. 14.6±4.9 degree, p<0.05) could be demonstrated in cTOF patients with normally directed LV rotational mechanics with preserved LV basal rotation regardless of previous procedure. pcTOF patients showed significantly reduced LV apical rotation as compared to that of etrTOF cases (3.2±3.7 degree vs. 7.1±2.5 degree, p<0.05). From the 7 cTOF patients with clockwise LV-RBR, apical and basal LV rotation proved to be −6.8±5.4 degree and −4.9±2.4 degree, respectively with LV apico-basal gradient of 4.3±3.6 degree. The mean LV apical and basal LV rotation of 3 cTOF patients with counterclockwise LV-RBR prove to be −2.1±3.4 degree and 0.2±0.9 degree, respectively with LV apico-basal gradient of 2.5±2.4 degree. Significant correlations could be demonstrated between LV apical rotation and aortic stiffness index (r=−0.55, p=0.03) and aortic distensibility (r=0.52, p=0.04).

Conclusions

Significant LV rotational abnormalities could be demonstrated in cTOF with the high prevalence of LV-RBR. cTOF patients with early total reconstruction proved to have beneficial results. Abnormal physiologic response of LV rotational mechanics to increased aortic stiffness can be detected in cTOF patients without LV-RBR.

Funding Acknowledgement

Type of funding source: None

Characterization of myocardial sodium-glucose cotransporter 1 expression in humans with heart failure and reduced ejection fraction

Introduction

In diabetic patients, multiple cardiovascular outcome trials consistently showed the robust cardioprotective effects of the novel antidiabetic agents, sodium glucose cotransporter 2 (SGLT2) inhibitors. However, the DAPA-HF study using the SGLT2 inhibitor dapagliflozin have extended these observations onto non-diabetic patients with heart failure (HF), urging previous hypotheses regarding the cardioprotective effects of SGLT2 inhibitors to be revised. This is further complicated by the fact that SGLT2 is not expressed in the human myocardium neither under normal nor diseased states. Hence, it has been postulated that SGLT2 inhibitors might exert direct cardioprotection via non-specific inhibition of SGLT1, which is in turn highly expressed in the myocardium.

Purpose

Because literature data is scarce regarding the expression profile of myocardial SGLT1, we aimed to characterize left ventricular SGLT1 expression in humans with end-stage HF accordingly to HF aetiology and to investigate whether cardiac resynchronization therapy (CRT) affects SGLT1 expression.

Methods

From patients undergoing mitral valve replacement with otherwise no myocardial disease and preserved LV function, we collected control papillary muscles (Control, n=9). From patients with end-stage HF undergoing heart transplantation (n=72), we obtained LV anterior wall samples according to the following HF aetiology groups: hypertrophic cardiomyopathy (HCM, n=7); idiopathic dilated cardiomyopathy (DCM, n=12); ischaemic heart disease (IHD, n=14), IHD with type 2 diabetes mellitus (IHD+T2DM, n=11); and patients with CRT (CRT-DCM, n=9; CRT-IHD, n=9; CRT-IHD+T2DM, n=10). We measured LV SGLT1 expression on the gene and protein expression levels using qRT-PCR and western blotting, respectively. Echocardiography-derived LV end-diastolic diameter (LVEDD) and LV ejection fraction (LVEF) were registered prior to surgery.

Results

Compared to controls, LV SGLT1 mRNA and protein expressions were significantly upregulated in patients with DCM, IHD and IHD+T2DM (all P<0.05), but not in HCM. In these patient groups, LV SGLT1 mRNA expression showed a significant positive correlation with LVEDD (r=0.493; P<0.001) and significant negative correlation with LVEF (r=−0.477; P<0.001). On the protein expression level, CRT was associated with significant reduction in LV SGLT1 only in patients with DCM and IHD, but not in IHD+T2DM.

Conclusions

Myocardial SGLT1 is upregulated in patients with HF (except HCM), and correlated strongly with parameters (LVEDD, LVEF) related to adverse LV remodelling. CRT was associated with reduced SGLT1 expression in DCM and IHD patients, but not in those with IHD+T2DM. Our results suggest that SGLT1 is upregulated in HF and might be implicated in adverse myocardial remodelling. Accordingly, whether SGLT2 inhibitors exert direct cardioprotection in HFrEF via non-specific inhibition of SGLT1 needs to be further elucidated.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary, Higher Education Institutional Excellence Programme of the Ministry of Human Capacities of Hungary

Effect of cardiac resynchronization therapy on left ventricular fibrosis-related mRNA expression profile in patients with end-stage heart failure

Background

When indicated, cardiac resynchronization therapy (biventricular pacing, CRT) decreases mortality in patients with heart failure (HF) and reduced ejection fraction, especially in those with non-ischemic cardiomyopathy. This is reflected by relatively rapid improvement of left ventricular (LV) end-diastolic diameter (LVEDD) and LV ejection fraction (LVEF) indicating reverse remodelling. These LV structural and functional improvements are accompanied by characteristic changes in LV gene expression profile. However, whether beneficial gene expression alterations related to biventricular pacing are sustained independently of structural and functional reverse remodelling is unclear.

Purpose

We aimed to compare LV fibrosis-related mRNA expression profile in end-stage HF patients with idiopathic dilated cardiomyopathy (DCM) who were not on CRT versus to those on CRT.

Methods

Left ventricular myocardial samples were harvested from end-stage HF patients undergoing heart transplantation (HTX). Inclusion criteria were negative family history of DCM, negative coronarography (i.e. non-ischemic), no relevant comorbidity (e.g. diabetes, hypertension) and no history of myocarditis. Accordingly, the following patient groups were included: 1.) DCM (n=12, 17% female, mean age [±standard deviation] 46.8±11.8 years) without CRT and 2.) CRT-DCM (n=12, 42% female, mean age 47.8±12.3 years) which comprised DCM patients on active CRT for mean 3.2±2.4 years until HTX. LV RNA was extracted and subjected to a commercially available mRNA expression panel interrogating 760 genes related to the development and regulation of fibrosis. Normalization to 10 housekeeping genes and batch corrections were conducted as per protocol. LV mRNA expression of atrial-natriuretic peptide (ANP) was quantified using qRT-PCR.

Results

Markers of reverse remodelling including LVEDD (73.4±8.3 mm vs 75.4±9.9 mm), LVEF (21.9±3.7% vs 18.5±6.8%) and LV ANP mRNA expression (arbitrary units: 1.05±1.80 vs 1.04±0.88) were comparable between DCM and CRT-DCM patients (all P>0.05), respectively. High-throughput mRNA expression screening revealed significant (all P<0.001) downregulation of 3 genes proven to be implicated in adverse LV remodelling: alpha catalytic subunit of protein phosphatase 2 (PPP2CA), interleukin 20 receptor subunit beta (IL20RB) and lipoprotein lipase (LPL). According to pathway analysis using directed significance scores, CRT was associated with collective upregulation of genes modifying complement activation (SERPING1, C1S, CFH) and collective downregulation of genes promoting cell proliferation (PPP2CA, ANAPC7, HSP90AA1, CSNK2B).

Conclusions

Independently of structural and functional reverse remodelling, CRT might be associated with slightly favourable LV expression profile of genes related to the regulation and development of fibrosis. This suggests that biventricular pacing might be beneficial on the molecular level beyond improvement of LV structure and function.

Funding Acknowledgement

Type of funding source: Public grant(s) – National budget only. Main funding source(s): National Research, Development and Innovation Fund of Hungary, Higher Education Institutional Excellence Programme of the Ministry of Human Capacities of Hungary

P1338 Anomalous left coronary artery from pulmonary artery syndrome diagnosed in adulthood: case of a mother of five

Funding Acknowledgements

Project no. NVKP_16-1-2016-0017 has been implemented with the support provided from the National Research, Development and Innovation Fund of Hungary

Introduction

Bland-White-Garland syndrome or ALCAPA (anomalous left coronary artery from pulmonary artery) syndrome is a rare congenital disorder with a prevalence of 1: 300,000. This condition is one the most common causes of infant myocardial infarction. It can ultimately lead to heart failure before the age of one, however when pronounced left and right coronary artery collateralization is present, patients may remain asymptomatic until older age. Due to the development and availability of non-invasive imaging techniques, these patients diagnosed more frequently in recent years.

Case description: We present a 53-year-old patient with treated hypertension and five uncomplicated pregnancies. At the age of 40, the patient was referred to coronary angiography due to her dyspnea on exertion. The examination showed that the left main coronary artery (LMCA) originates from the pulmonary artery 7 mm above the pulmonary valve and the right coronary artery is significantly dilated. Based on the mild complaints and good left ventricle systolic function, conservative therapy was recommended by the cardiac surgery team. Since 2018 the patient has had gradually worsening complaints despite of the therapy adjusted for chronic heart failure. Q-waves were depicted on the 12-lead ECG in aVL and V1-V6 leads. Echocardiography showed dilated left ventricle (LV), LV hypertrophy, diffuse hypokinesia, decreased LV systolic function and diastolic dysfunction. At our clinic, we performed cardiac magnetic resonance imaging (CMR) which showed moderately reduced LV ejection fraction, diffuse LV hypokinesia, increased LV volume, septal LV hypertrophy. We visualized the retrograde flow on the LMCA, the shunt volume at the anomalous artery was 1,27 L/min. The CMR also showed irreversible damage of the subendocardial region of the myocardium via late gadolinium enhancement in the area supplied by the LMCA. Since we planned to reevaluate the surgical possibilities, the collateral network with tortuous and dilated left and right coronary arteries were visualized by coronary CT angiography. The surgical team at our institute decided to perform myocardial revascularization and restoration of dual coronary artery supply.

Discussion

ALCAPA is usually diagnosed in infancy however, in about 10-15% of cases the disease is only recognized in adulthood. The long-term morphological and functional characteristics of the syndrome may include reversible/irreversible ischemic damage, systolic and diastolic dysfunction, mitral regurgitation, significant collateral circulation, left-to-right shunt, dilated coronary arteries. Surgical myocardial revascularization and restoration of dual coronary artery supply is recommended even in adult patients.

Abstract P1338 Figure. CTA reconstruction and LGE CMR

P1713Predictors of mortality following extracorporeal membrane oxygenation support in a large unselected critically ill patient population

Background

Mechanical circulatory support (MCS) has been established as a means of augmenting circulation in critically ill patients due to a variety of underlying clinical reasons. Different methods of MCS may be applied with the venous-arterial extracorporeal membrane oxygenation (VA-ECMO) system being one of the most utilized in everyday care.

Objectives

Our aim was to determine independent predictors of mortality following VA-ECMO therapy in a large, unselected, adult, critically ill patient population requiring MCS.

Methods

Data on 181 consecutive, real-world VA-ECMO treatments have been assessed. Analysis was conducted for all subjects requiring MCS with the VA-ECMO as first instalment, regardless of underlying cause or eventual upgrade. All potential clinical factors influencing mortality were examined and evaluated.

Results

Overall mortality amounted to ≈65% at a median follow-up of 28 days and depended upon: glomerular filtration rate of <60 ml/min/1.73 m2 (HR: 1.53; p=0.03) and age ≥65 years (HR: 1.65; p=0.02) based on multivariate Cox regression analysis. However, prolonged ECMO time, conversion of the ECMO to longer duration MCS, diabetes, prior ACS or revascularization, reduced left ventricular ejection fraction (EF) had no effect on adverse mortality outcomes (all p>0.05). Surprisingly, neither the need for resuscitation during MCS nor any ECMO implantation indication influenced mortality by itself (p>0.05).

Conclusions

We have found that mortality in critically ill patients requiring VA-ECMO use remains very high. Decreased renal function and advanced age were found to influence mortality in our all-comers patient population, while traditional predictors of cardiovascular mortality did not have a significant effect on survival.

P761The effect of extracorporeal photopheresis on cardiac allograft rejection and on lymphocyte subclasses

Background

Cardiac allograft rejection is known to have a profound impact on graft survival and mortality after heart transplant. Previous data on the efficacy of extracorporeal photopheresis (ECP) in the management of cardiac allograft rejection is encouraging. Though, clear evidence on the exact indication and data regarding its effect on distinct lymphocyte subtypes are still lacking. Based on their cytokine production, both helper and cytotoxic T cells can differentiate into either regulatory cells participating in the suppression of rejection or into effector cells responsible for its maintenance. Regulatory T cells are essential for the termination of rejection, while B lymphocytes and natural killer (NK) cells contribute to it.

Purpose

We aimed to investigate the anti-rejection efficacy and the impact of ECP on peripheral blood lymphocyte subclasses in adult heart transplant recipients.

Methods

In a retrospective analysis of 12 consecutive patients treated with ECP for cardiac allograft rejection between 2013 and 2019, we examined the grade of rejection in endomyocardial biopsies (EMB) based on the International Society for Heart and Lung Transplantation classification. We analysed the absolute counts and the percentages of helper, cytotoxic and regulatory T cells, B lymphocytes and NK cells with fluorescence activated cell sorting. Measurements were performed both before and after the ECP treatment period. Data values were given as either mean±standard deviation or median [min–max].

Results

The patients underwent 26 [2–39] ECP treatments in addition to standard immunosuppressant therapy. Whereas grade 2R cellular rejection was detected in 83% of the cases prior to initiating ECP, none of the examined EMB specimen revealed rejection greater than grade 1R cellular rejection post ECP therapy. The average grade of cellular rejection improved significantly (1.25±0.45 vs. 0.50±0.53; p=0.022). The absolute count and the percentage of helper T cells increased significantly post ECP therapy (0.34 G/l±0.26 G/l vs. 0.51 G/l±0.39 G/l; p=0.018 and 3.43%±2.24% vs. 5.98%±3.64%; p=0.017, respectively). There was also a significant rise in the percentage of cytotoxic T cells (2.33%±1.46% vs. 4.16±2.98%; p=0.027). We noticed an almost significant twofold increase in the percentage of regulatory T cells on completion of the ECP therapy (0.20%±0.22% vs. 0.37%±0.20%; p=0.060). Neither B lymphocyte nor NK cell counts revealed any significant changes.

Conclusion

ECP was effective in reducing the severity of cardiac allograft rejection episodes. The significant decrease in rejection rates might be indicative of the predominance of anti-inflammatory helper and cytotoxic T cell subpopulations and the increase of regulatory T cell count post ECP therapy. However, discussion of the results are limited by small sample size and the effect of medical therapy on the lymphocytes.

5939Perioperative shift in right ventricular mechanical pattern in patients undergoing mitral valve surgery: a predictor of right ventricular failure?

Background

Severe mitral regurgitation (MR) induces significant changes not only in the left, but also in the right ventricular (RV) morphology and function. Early treatment of MR is recommended, however, surgical procedure disrupts the native RV contractile pattern and predisposes the at-risk ventricle to develop postoperative RV failure (RVF) which is associated with poor outcomes.

Purpose

Accordingly, the PREPARE-MVR study (PRediction of Early PostoperAtive Right vEntricular failure in Mitral Valve Replacement/Repair patients) aims to explore the alterations of RV contraction pattern in patients undergoing MVR and to investigate the association of preoperative echocardiographic findings with early postoperative RVF.

Methods

We prospectively enrolled 70 patients (62±12 years, 67% males) undergoing open heart MVR. Thirty age and gender matched healthy volunteers served as control group. Transthoracic 3D echocardiography was performed preoperatively and at intensive care unit discharge. Furthermore, focused 2D echocardiogram was also obtained during the ICU stay. Forty-three patients also completed 6 months follow-up. 3D model of the RV was reconstructed and end-diastolic volume index (EDVi) along with RV ejection fraction (RVEF) were calculated. For in-depth analysis of RV mechanics, we decomposed the motion of the RV to compute longitudinal (LEF) and radial ejection fraction (REF). Right heart catheterization was performed to monitor RV stroke work index (RVSWi).

Results

RV morphology as assessed by EDVi was unaffected by surgery (preoperative vs postoperative; 73±17 vs 71±16 mL/m2, p=NS). RVEF was slightly decreased after MVR (52±6 vs 48±7%, p<0.05), whereas RV contraction pattern has changed notably. Before MVR, the longitudinal shortening was the main contributor to global systolic function (LEF/RVEF vs REF/RVEF; 0.53±0.10 vs 0.43±0.12; p<0.001), whereas in controls the longitudinal and radial shortening contributed equally to RVEF (0.47±0.07 vs 0.43±0.09; p=NS). Postoperatively, the radial motion became dominant (0.35±0.08 vs 0.47±0.09; p<0.001). However, this shift was only temporary as 6 months later the contraction pattern became similar to controls showing equal contribution of the two components (0.44±0.10 vs 0.42±0.11; p=NS). Postoperative RVF (defined as RVSWi <300 mmHg*mL/m2 or ICU TAPSE <10 mm) was detected in 14 [20%] patients. Preoperative LEF was associated with postoperative RVSWi (r=−0.61, p<0.001) and it was an independent predictor of postoperative RVF (OR=1.16 [1.03–1.35], p<0.05).

Conclusion

Severe MR induces a significant shift in the RV mechanical pattern which may influence the development of postoperative RV dysfunction and failure after MVR. Advanced indices of RV mechanics are associated with invasively measured parameters of RV contractility and may predict postoperative RVF.