Borlaug, Barry A

Abstract Aims The Fontan operation is associated with significant long-term morbidity and mortality, posing challenges in management. No haemodynamic classification has been established to aid management and prognostication of patients with Fontan palliation. Our aim was to assess haemodynamic profiles for Fontan patients and evaluate their relationships to prognosis. Methods and results Eighty-four adult Fontan patients without obstruction or significant valve disease undergoing cardiac catheterization for Fontan-related co-morbidities were divided into four different haemodynamic profiles based on normal/high Fontan pressures (FP) (< 15 or ≥ 15 mmHg) and low/normal cardiac index (CI) (< 2.5 or ≥ 2.5 L/min/m2). Fourteen patients had low CI/high FP (17%), 24 low CI/normal FP (29%), 20 normal CI/high FP (24%), and 26 normal CI/normal FP (31%). Demographic and clinical data were similar among groups except for a trend towards a higher prevalence of cirrhosis in the normal CI/high FP (50%) group. Systemic vascular afterload, assessed by systemic vascular resistance and effective arterial elastance, was higher in patients with low CI/high FP and low CI/normal FP as compared to normal CI profiles. Pulmonary vascular resistance indices were higher in patients with low CI/high FP than all other profiles. The normal CI/high FP haemodynamic profile was an independent predictor of mortality (hazard ratio 4.1, 95% confidence interval 1.2–11.5). Heterotaxy and protein-losing enteropathy were also predictors of mortality on the multivariate model. Conclusion The proposed haemodynamic classification provides prognostic information in adults post-Fontan with patients in the normal CI/high FP profile having worse survival. Whether this classification can guide management in these patients deserves further investigation.

Rationale: Pulmonary vascular resistance fails to decrease appropriately during exercise in patients with heart failure with preserved ejection fraction (HFpEF). Interventions that enhance pulmonary vasodilation might be beneficial in this cohort but could also worsen left atrial hypertension, exacerbating lung congestion. Intravenous β-agonists reduce pulmonary vascular resistance but are not suitable for chronic use. Objective: We hypothesized that the inhaled β-adrenergic agonist albuterol would improve pulmonary vasodilation during exercise in patients with HFpEF, without increasing left heart filling pressures. Methods and Results: We performed a randomized, double-blind, placebo-controlled trial testing the effects of inhaled albuterol on resting and exercise hemodynamics in subjects with HFpEF using high-fidelity micromanometer catheters and expired gas analysis. The primary end point was pulmonary vascular resistance during exercise. Subjects with HFpEF (n=30) underwent resting and exercise hemodynamic assessment and were then randomized 1:1 to inhaled, nebulized albuterol or placebo. Rest and exercise hemodynamic testing was then repeated. Albuterol improved the primary end point of exercise pulmonary vascular resistance as compared with placebo (−0.6±0.5 versus +0.1±0.7 WU; P =0.003). Albuterol enhanced cardiac output reserve and right ventricular pulmonary artery coupling, reduced right atrial and pulmonary artery pressures, improved pulmonary artery compliance, and enhanced left ventricular transmural distending pressure (all P <0.01), with no increase in pulmonary capillary hydrostatic pressures. Conclusions: Albuterol improves pulmonary vascular reserve in patients with HFpEF without worsening left heart congestion. Further study is warranted to evaluate the chronic efficacy of β-agonists in HFpEF and other forms of pulmonary hypertension. Clinical Trial Registration: URL: http://www.clinicaltrials.gov . Unique identifier: NCT02885636.

Objective To assess the association between cardiac morphology and function assessed with cardiac MRI (CMRI) and haemodynamics at rest and during exercise in patients with primary mitral regurgitation (MR). Methods In an observational study, subjects with significant primary MR (N = 46) with effective regurgitant orifice ≥ 0.30 cm2 and left ventricular (LV) ejection fraction > 60% were examined with right heart catheterisation during rest and exercise and CMRI at rest. End-diastolic pressure volume relationship (EDPVR) was assessed using a single beat method using pulmonary capillary wedge pressure (PCWP) and end-diastolic volume. Patients were divided according to normal PCWP at rest (> 12 mm Hg) and with exercise (> 28 mm Hg). Results: Resting regurgitant volume correlated positively with resting PCWP, (r = 0.42, p = 0.002). However, with exercise no association between PCWP and regurgitant volume was seen (r = 0.09, p = 0.55). At rest left atrial (LA) maximal, minimal and volume index at atrial contraction correlated positively with PCWP (r = 0.60; r = 0.55; r = 0.58, all p < 0.001); in contrast none of these correlated with exercise PCWP (all p > 0.2). EDPVR in patients with high PCWP at rest was shifted towards higher volumes for the same pressures. The opposite was seen for patients with high PCWP during exercise where estimated volumes were smaller for the same pressure than patients with normal exercise PCWP. Conclusion In patients with significant MR the degree of regurgitation and LA dilatation is associated with resting PCWP. However, with exercise this association disappears. Estimation of EDPVR suggests lower LV compliance in patients where PCWP is increased with exercise. Clinical trial registration URL: https://clinicaltrials.gov/ct2/show/NCT02961647?term=HEMI&rank=1. ID: NCT02961647

Background We sought to study the prevalence of high‐sensitivity troponin and its association with cardiac structure and outcomes in ambulatory and hospitalized patients with heart failure with a preserved ejection fraction ( HF p EF ). Methods and Results A post hoc analysis utilized data from HF p EF patients: DOSE (Diuretic Optimization Strategies Evaluation) and CARRESS ‐ HF (Cardiorenal Rescue Study in Acute Decompensated Heart Failure) enrolled patients hospitalized with acute HF p EF , and RELAX (Phosphodiesterase‐5 Inhibition to Improve Clinical Status and Exercise Capacity in Heart Failure With Preserved Ejection Fraction) enrolled ambulatory patients with HF p EF . High‐sensitivity troponin I (hs‐TnI) was measured in hospitalized patients at baseline, at 72 to 96 hours, on day 7, and on day 60. In ambulatory patients hs‐TnI was measured at baseline and at week 24. In the ambulatory cohort, correlations between hs‐TnI and cardiac structure and function were assessed. The association between hs‐TnI and a 60‐day composite of emergency room visits, readmissions, and death was assessed for hospitalized patients using multivariable Cox proportional hazard models. The study population included 139 hospitalized and 212 ambulatory patients with HF p EF and hs‐TnI measured at baseline. The median (25th, 75th percentiles) baseline troponin was 17.6 (11.1, 41.0) ng/L in hospitalized patients and 9.5 (5.3, 19.7) ng/L in ambulatory patients ( P <0.001). The prevalence of elevated hs‐TnI (>99% percentile upper reference limit was 86% in hospitalized patients and 53% among ambulatory patients, with stable elevation in ambulatory patients during follow‐up. HF p EF patients with a hs‐TnI above the median were older with worse left ventricular hypertrophy and diastolic dysfunction. Continuously valued hs‐TnI (per doubling) was associated with increased risk of composite end point (adjusted hazard ratio 1.20, 95% confidence interval 1.00‐1.43; P =0.042). Conclusions Hs‐TnI is commonly elevated among both hospitalized and ambulatory patients with HF p EF . Increased hs‐TnI levels are associated with worse cardiac structure and increased risk of adverse events.

Abstract Aims Prevalent right ventricular (RV) dysfunction (RVD) is associated with increased mortality in patients with heart failure with preserved ejection fraction (HFpEF), but no study has characterized long-term changes in RV structure and function within the same patient. Methods and results Patients with unequivocal HFpEF defined by either invasive haemodynamics or hospitalization for pulmonary oedema (n = 271) underwent serial echocardiographic evaluations &gt;6 months apart. Clinical, structural, functional, and haemodynamic characteristics were examined. Over a median of 4.0 years (interquartile range 2.1–6.1), there was a 10% decline in RV fractional area change and 21% increase in RV diastolic area (both P &lt; 0.0001). These changes greatly exceeded corresponding changes in the left ventricle. The prevalence of tricuspid regurgitation increased by 45%. Of 238 patients with normal RV function at Exam 1, 55 (23%) developed RVD during follow-up. Development of RVD was associated with both prevalent and incident atrial fibrillation (AF), higher body weight, coronary disease, higher pulmonary artery and left ventricular filling pressures, and RV dilation. Patients with HFpEF developing incident RVD had nearly two-fold increased risk of death (adjusted hazard ratio 1.89, 95% confidence interval 1.01–3.44; P = 0.04). Conclusion While previous attention has centred on the left ventricle in HFpEF, these data show that right ventricular structure and function deteriorate to greater extent over time when compared with changes in the left ventricle. Further study is required to evaluate whether interventions targeting modifiable risk factors identified for incident RVD, including abnormal haemodynamics, AF, coronary disease, and obesity, can prevent RVD and thus improve outcomes.

Aims: Acute increases in left ventricular end diastolic pressure (LVEDP) can induce pulmonary edema (PE). The mechanism(s) for this rapid onset edema may involve more than just increased fluid filtration. Lung endothelial cell permeability is regulated by pressure-dependent activation of nitric oxide synthase (NOS). Herein, we demonstrate that pressure-dependent NOS activation contributes to vascular failure and PE in a model of acute heart failure (AHF) caused by hypertension. Methods and results: Male Sprague–Dawley rats were anesthetized and mechanically ventilated. Acute hypertension was induced by norepinephrine (NE) infusion and resulted in an increase in LVEDP and pulmonary artery pressure (Ppa) that were associated with a rapid fall in PaO2, and increases in lung wet/dry ratio and injury scores. Heart failure (HF) lungs showed increased nitrotyrosine content and ROS levels. L-NAME pretreatment mitigated the development of PE and reduced lung ROS concentrations to sham levels. Apocynin (Apo) pretreatment inhibited PE. Addition of tetrahydrobiopterin (BH4) to AHF rats lung lysates and pretreatment of AHF rats with folic acid (FA) prevented ROS production indicating endothelial NOS (eNOS) uncoupling. Conclusion: Pressure-dependent NOS activation leads to acute endothelial hyperpermeability and rapid PE by an increase in NO and ROS in a model of AHF. Acute increases in pulmonary vascular pressure, without NOS activation, was insufficient to cause significant PE. These results suggest a clinically relevant role of endothelial mechanotransduction in the pathogenesis of AHF and further highlights the concept of active barrier failure in AHF. Therapies targetting the prevention or reversal of endothelial hyperpermeability may be a novel therapeutic strategy in AHF.

Background: Heart failure (HF) is often associated with iron deficiency (ID). Skeletal muscle abnormalities are common in HF, but the potential role of ID in this phenomenon is unclear. In addition to hemopoiesis, iron is essential for muscle bioenergetics. We examined whether energetic abnormalities in skeletal muscle in HF are affected by ID and if they are responsive to intravenous iron. Methods and Results: Forty-four chronic HF subjects and 25 similar healthy volunteers underwent 31 P magnetic resonance spectroscopy of calf muscle at rest and during exercise (plantar flexions). Results were compared between HF subjects with or without ID. In 13 ID-HF subjects, examinations were repeated 1 month after intravenous ferric carboxymaltose administration (1000 mg). As compared with controls, HF subjects displayed lower resting high-energy phosphate content, lower exercise pH, and slower postexercise PCr recovery. Compared with non-ID HF, ID-HF subjects had lower muscle strength, larger PCr depletion, and more profound intracellular acidosis with exercise, consistent with an earlier metabolic shift to anaerobic glycolysis. The exercise-induced PCr drop strongly correlated with pH change in HF group ( r =−0.71, P <0.001) but not in controls ( r =0.13, P =0.61, interaction: P <0.0001). Short-term iron administration corrected the iron deficit but had no effect on muscle bioenergetics assessed 1 month later. Conclusions: HF patients display skeletal muscle myopathy that is more severe in those with iron deficiency. The presence of ID is associated with greater acidosis with exercise, which may explain early muscle fatigue. Further study is warranted to identify the strategy to restore iron content in skeletal muscle.