Publications by authors named "George Amin-Youssef"

Aims: Skeletal muscle energetic augmentation might be a mechanism via which intravenous iron improves symptoms in heart failure, but no direct measurement of intrinsic mitochondrial function has been performed to support this notion. This molecular substudy of the FERRIC-HF II trial tested the hypothesis that ferric derisomaltose (FDI) would improve electron transport chain activity, given its high dependence on iron-sulfur clusters which facilitate electron transfer during oxidative phosphorylation.

Methods And Results: Vastus lateralis skeletal muscle biopsies were taken before and 2 weeks after randomization.

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Background: Ventricular arrhythmia is an important cause of mortality in patients with ischemic left ventricular dysfunction. Revascularization with coronary artery bypass graft or percutaneous coronary intervention is often recommended for these patients before implantation of a cardiac defibrillator because it is assumed that this may reduce the incidence of fatal and potentially fatal ventricular arrhythmias, although this premise has not been evaluated in a randomized trial to date.

Methods: Patients with severe left ventricular dysfunction, extensive coronary disease, and viable myocardium were randomly assigned to receive either percutaneous coronary intervention (PCI) plus optimal medical and device therapy (OMT) or OMT alone.

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Aims: Iron deficiency (ID) is prevalent and adverse in chronic heart failure (CHF) but few human studies have explored the myocardial mechanism(s) that potentially underlie this adversity. Because mitochondrial oxidative phosphorylation (OXPHOS) provides over 90% of the hearts adenosine triphosphate (ATP), and iron is critical for OXPHOS, we hypothesized that patients with CHF and ID would harbour greater cardiac energetic impairments than patients without ID.

Methods And Results: Phosphorus magnetic resonance spectroscopy was used to quantify the phosphocreatine (PCr) to ATP (PCr/ATP) ratio, an index of in-vivo cardiac energetics, in CHF patients and healthy volunteers.

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Introduction: 18F-fluorodeoxyglucose positron emission tomography (F-FDG-PET/CT) is not routinely recommended for the diagnosis of infective endocarditis (IE) due to the lack of clinical impact.

Materials And Methods: Between January 2016 and January 2020, clinical data from patients with a possible diagnosis of IE were reviewed retrospectively to evaluate the value of F-FDG-PET/CT in the diagnosis of IE. F-FDG PET/CT scan was performed as an additional diagnostic tool in possible IE when echocardiography was inconclusive or in patients with definite IE to identify extracardiac complications.

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Introduction: Culture-negative infective endocarditis (IE) accounts for 7-31% of all cases. Metagenomics has contributed to improving the aetiological diagnosis of IE patients undergoing valve surgery. We assessed the impact of 16S ribosomal DNA gene polymerase chain reaction (16S rDNA PCR) in the aetiological diagnosis of culture-negative IE.

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Background: Life-threatening arrhythmias (LTAs) can trigger sudden cardiac death or provoke implantable cardioverter-defibrillator (ICD) discharges that escalate morbidity and mortality. Longitudinal myofibrils predominate in the subendocardium, which is uniquely sensitive to arrhythmogenic triggers. In this study, we test the hypothesis that mitral annular systolic velocity (S'), a simple routinely obtained tissue Doppler index of LV long-axis systolic function, might predict lethal arrhythmias irrespective of left ventricular ejection fraction (LVEF).

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Papillary muscle (PM) rupture can usually complicate inferior or posterior myocardial infarctions, but selective PM infarction is extremely rare, and the exact underlying pathophysiological mechanism is not entirely clear. We present a case of PM rupture due to isolated PM infarction in a patient with unobstructed coronary arteries, which could be misdiagnosed as a vegetation or other mass given the absence of regional wall motion abnormalities (RWMAs) on transthoracic echocardiogram. Our case highlights that in patients with severe mitral regurgitation and associated mitral valve mass, the absence of RWMAs should not exclude ischemic PM rupture from differential diagnosis.

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Objectives: Congestion is associated with worse outcomes in critically ill surgical patients but can be difficult to quantify noninvasively. We hypothesised that plasma volume status (PVS), estimated preoperatively using a validated formula that enumerates percentage change from ideal plasma volume (PV), would provide incremental prognostic utility after coronary artery bypass graft (CABG) surgery.

Methods: In this retrospective cohort study, patients who underwent CABG surgery (1999-2010) were identified from a prospectively collected database.

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Background: Iron repletion augments exercise capacity in chronic heart failure (HF), but there is a lack of mechanistic data explaining how iron could augment exercise performance despite minimal changes in hemoglobin (Hb). Besides Hb, iron is an obligate component of mitochondrial enzymes that generate cellular energy in the form of adenosine triphosphate and phosphocreatine (PCr). Dynamic phosphorus magnetic resonance spectroscopy is a noninvasive tool that quantifies in vivo muscle energetics by measuring the kinetics of PCr recovery after exertion.

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Soluble ST2 (sST2) is a novel biomarker implicated in myocardial remodeling and fibrosis. Recent studies in normal subjects have suggested that the biologic variability (BV) of sST2 is significantly lower than that of the B-type natriuretic peptides and N-terminal pro B-type natriuretic peptide (NTproBNP). It may, consequently, be a better biomarker for monitoring patients with chronic heart failure (CHF).

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Background: Soluble ST2 (sST2) is an emerging biomarker of cardiac remodelling and fibrosis. Studies indicate that it is predictive of mortality in acutely decompensated heart failure. The role of sST2 in chronic heart failure (CHF) is less well defined.

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