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Heart rate reduction by If-inhibition improves vascular stiffness and left ventricular systolic and diastolic function in a mouse model of heart failure with preserved ejection fraction.

ABSTRACT: In diabetes mellitus, heart failure with preserved ejection fraction (HFPEF) is a significant comorbidity. No therapy is available that improves cardiovascular outcomes. The aim of this study was to characterize myocardial function and ventricular-arterial coupling in a mouse model of diabetes and to analyse the effect of selective heart rate (HR) reduction by If-inhibition in this HFPEF-model.Control mice, diabetic mice (db/db), and db/db mice treated for 4 weeks with the If-inhibitor ivabradine (db/db-Iva) were compared. Aortic distensibility was measured by magnetic resonance imaging. Left ventricular (LV) pressure-volume analysis was performed in isolated working hearts, with biochemical and histological characterization of the cardiac and aortic phenotype. In db/db aortic stiffness and fibrosis were significantly enhanced compared with controls and were prevented by HR reduction in db/db-Iva. Left ventricular end-systolic elastance (Ees) was increased in db/db compared with controls (6.0 ± 1.3 vs. 3.4 ± 1.2 mmHg/µL, P < 0.01), whereas other contractility markers were reduced. Heart rate reduction in db/db-Iva lowered Ees (4.0 ± 1.1 mmHg/µL, P < 0.01), and improved the other contractility parameters. In db/db active relaxation was prolonged and end-diastolic capacitance was lower compared with controls (28 ± 3 vs. 48 ± 8 ?L, P < 0.01). These parameters were ameliorated by HR reduction. Neither myocardial fibrosis nor hypertrophy were detected in db/db, whereas titin N2B expression was increased and phosphorylation of phospholamban was reduced both being prevented by HR reduction in db/db-Iva.In db/db, a model of HFPEF, selective HR reduction by If-inhibition improved vascular stiffness, LV contractility, and diastolic function. Therefore, If-inhibition might be a therapeutic concept for HFPEF, if confirmed in humans.

SUBMITTER: Reil JC

PROVIDER: S-EPMC3858102 | biostudies-literature | 2013 Sep

REPOSITORIES: biostudies-literature

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Heart rate reduction by If-inhibition improves vascular stiffness and left ventricular systolic and diastolic function in a mouse model of heart failure with preserved ejection fraction.

Reil Jan-Christian JC Hohl Mathias M Reil Gert-Hinrich GH Granzier Henk L HL Kratz Mario T MT Kazakov Andrey A Fries Peter P Müller Andreas A Lenski Matthias M Custodis Florian F Gräber Stefan S Fröhlig Gerd G Steendijk Paul P Neuberger Hans-Ruprecht HR Böhm Michael M

European heart journal 20120724 36

<h4>Aims</h4>In diabetes mellitus, heart failure with preserved ejection fraction (HFPEF) is a significant comorbidity. No therapy is available that improves cardiovascular outcomes. The aim of this study was to characterize myocardial function and ventricular-arterial coupling in a mouse model of diabetes and to analyse the effect of selective heart rate (HR) reduction by If-inhibition in this HFPEF-model.<h4>Methods and results</h4>Control mice, diabetic mice (db/db), and db/db mice treated fo ...[more]

PMID: 22833515

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Project description:ObjectivesTo determine clinical and prognostic differences between preserved and deteriorated systolic function (defined as left ventricular (LV) ejection fractions > or = 50% and < 50%, respectively) in patients with heart failure satisfying modified Framingham criteria.Patients and methodsRecords were studied of 1252 patients with congestive heart failure (CHF) (mean (SD) age 69.4 (11.7) years; 485 women, 767 men) who had been admitted to a cardiology service for CHF in the period 1991-2002 and whose LV systolic function had been echocardiographically evaluated within two weeks of admission. Data were collected on the main clinical findings, supplementary examinations, treatment, and duration of hospitalisation. Whether the patient was alive in the spring of 2003 was evaluated by searching the general archives of the hospital and by telephone survey.ResultsLV systolic function was preserved in 39.8% of patients. Age, female to male sex ratio, and prevalence of atrial fibrillation, valve disease, and other non-ischaemic, non-dilated cardiopathies were all significantly greater in the group with preserved systolic function. New York Heart Association functional class IV, third heart sound, jugular vein congestion, cardiomegaly, radiological signs of lung oedema, pathological Q waves, left bundle branch block, sinus rhythm, ischaemic cardiopathy, and dilated cardiomyopathy were all significantly more prevalent in the group with deteriorated systolic function, as was treatment with angiotensin converting enzyme inhibitors and most other antihypertensive drugs on discharge from hospital. There was no significant difference in survival between the groups with preserved and deteriorated systolic function (either survival regardless of age at admission or in subgroups aged < 75 and > or = 75 years at admission). In the whole group, survival rates after one, three, and five years were 84.0%, 66.7%, and 50.9%, respectively.ConclusionIn view of the poor prognosis of patients with CHF with preserved LV systolic function, who are currently treated empirically, it is to be hoped that relevant controlled clinical trials under way will afford information allowing optimisation of their treatment.

Project description:BackgroundArterial stiffness is thought to contribute to the pathophysiology of heart failure with preserved ejection fraction (HFpEF). We sought to examine arterial stiffness in HFpEF and hypertension and investigate associations of arterial and left ventricular hemodynamic responses to exercise.Methods and resultsA total of 385 symptomatic individuals with an EF of ≥50% underwent upright cardiopulmonary exercise testing with invasive hemodynamic assessment of arterial stiffness and load (aortic augmentation pressure, augmentation index, systemic vascular resistance index, total arterial compliance index, effective arterial elastance index, and pulse pressure amplification) at rest and during incremental exercise. An abnormal hemodynamic response to exercise was defined as a steep increase in pulmonary capillary wedge pressure relative to cardiac output (∆PCWP/∆CO > 2 mm Hg/L/min). We compared rest and exercise measures between HFpEF and hypertension in multivariable analyses. Among 188 participants with HFpEF (mean age 61 ± 13 years, 56% women), resting arterial stiffness parameters were worse compared with 94 hypertensive participants (mean age 55 ± 15 years, 52% women); these differences were accentuated during exercise in HFpEF (all P ≤ .0001). Among all participants, exercise measures of arterial stiffness correlated with worse ∆PCWP/∆CO. Specifically, a 1 standard deviation higher exercise augmentation pressure was associated with 2.15-fold greater odds of abnormal LV hemodynamic response (95% confidence interval 1.52-3.05; P < .001). Further, exercise measures of systemic vascular resistance index, elastance index, and pulse pressure amplification correlated with a lower peak oxygen consumption.ConclusionsExercise accentuates the increased arterial stiffness found in HFpEF, which in turn correlates with left ventricular hemodynamic responses. Unfavorable ventricular-vascular interactions during exercise in HFpEF may contribute to exertional intolerance and inform future therapeutic interventions.

Project description:AIMS:Neuregulin1-? (NRG1-?) is released from microvascular endothelial cells in response to inflammation with compensatory cardioprotective effects. Circulating NRG1-? is elevated in heart failure (HF) with reduced ejection fraction (HFrEF) but not studied in HF with preserved EF (HFpEF). METHODS AND RESULTS:Circulating NRG1-? was quantified in 86 stable patients with HFpEF (EF ?45% and N-terminal pro-brain natriuretic peptide >300 ng/L), in 86 patients with HFrEF prior to and after left ventricular assist device (LVAD) and/or heart transplantation (HTx) and in 21 healthy controls. Association between NRG1-? and the composite outcome of all-cause mortality/HF hospitalization in HFpEF and all-cause mortality/HTx/LVAD implantation in HFrEF with and without ischaemia assessed as macrovascular coronary artery disease was assessed. In HFpEF, median (25th-75th percentile) NRG1-? was 6.5 (2.1-11.3) ng/mL; in HFrEF, 3.6 (2.1-7.6) ng/mL (P = 0.035); after LVAD, 1.7 (0.9-3.6) ng/mL; after HTx 2.1 (1.4-3.6) ng/mL (overall P < 0.001); and in controls, 29.0 (23.1-34.3) ng/mL (P = 0.001). In HFrEF, higher NRG1-? was associated with worse outcomes (hazard ratio per log increase 1.45, 95% confidence interval 1.04-2.03, P = 0.029), regardless of ischaemia. In HFpEF, the association of NRG1-? with outcomes was modified by ischaemia (log-rank P = 0.020; Pinteraction = 0.553) such that only in ischaemic patients, higher NRG1-? was related to worse outcomes. In contrast, in patients without ischaemia, higher NRG1-? trended towards better outcomes (hazard ratio 0.71, 95% confidence interval 0.48-1.05, P = 0.085). CONCLUSIONS:Neuregulin1-? was reduced in HFpEF and further reduced in HFrEF. The opposing relationships of NRG1-? with outcomes in non-ischaemic HFpEF compared with HFrEF and ischaemic HFpEF may indicate compensatory increases of cardioprotective NRG1-? from microvascular endothelial dysfunction in the former (non-ischaemic HFpEF), but this compensatory mechanism is overwhelmed by the presence of ischaemia in the latter (HFrEF and ischaemic HFpEF).

Dataset Information

Heart rate reduction by If-inhibition improves vascular stiffness and left ventricular systolic and diastolic function in a mouse model of heart failure with preserved ejection fraction.

Publications

Heart rate reduction by If-inhibition improves vascular stiffness and left ventricular systolic and diastolic function in a mouse model of heart failure with preserved ejection fraction.

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