Borlaug, Barry A.

Reversal of pulmonary hypertension has been observed in patients during a bridge to transplant with a left ventricular assist device. Total artificial heart (TAH) implant prevents subsequent right heart catheterization. Consequently, controversy exists over whether the prosthetic right ventricle improves or exacerbates pulmonary hypertension. A pulmonary artery (PA) pressure monitor was placed in two patients undergoing TAH implant, as a bridge to transplant. One patient had pulmonary hypertension at implant; the other had normal pulmonary pressures. Daily measurements were taken of systolic, diastolic, and mean PA pressures throughout support. Patient 1 received successful transplant after TAH support of 91 days. Systolic/diastolic (mean) PA pressures steadily decreased from 55/39 (28) mm Hg at implant to 29/18 (7) mm Hg currently. Patient 2 received support for 101 days before death due to abdominal ischemic complications. Pulmonary arterial pressures stayed consistent throughout this period, from 26/17 (20) mm Hg at implant to 23/13 (17) mm Hg at the time of death. These findings suggest that an implantable PA pressure monitor may be useful in optimizing hemodynamics and planning appropriate timing of transplant with TAH support.

Approximately half of patients with heart failure have preserved ejection fraction. There is no proven treatment that improves outcome. The pathophysiology of heart failure with preserved ejection fraction is complex and includes left ventricular systolic and diastolic dysfunction, pulmonary vascular disease, endothelial dysfunction, and peripheral abnormalities. Multiple lines of evidence point to impaired nitric oxide (NO)-cGMP bioavailability as playing a central role in each of these abnormalities. In contrast to traditional organic nitrate therapies, an alternative strategy to restore NO-cGMP signaling is via inorganic nitrite. Inorganic nitrite, previously considered to be an inert byproduct of NO metabolism, functions as an important in vivo reservoir for NO generation, particularly under hypoxic and acidosis conditions. As such, inorganic nitrite becomes most active at times of greater need for NO signaling, as during exercise when left ventricular filling pressures and pulmonary artery pressures increase. Herein, we present the rationale and design for the INDIE-HFpEF trial (Inorganic Nitrite Delivery to Improve Exercise Capacity in Heart Failure with Preserved Ejection Fraction), which is a multicenter, randomized, double-blind, placebo-controlled cross-over study assessing the effect of inhaled inorganic nitrite on peak exercise capacity, conducted in the National Heart, Lung, and Blood Institute–sponsored Heart Failure Clinical Research Network. Clinical Trial Registration URL: http://www.clinicaltrials.gov . Unique identifier: NCT02742129.

Background— People with heart failure and preserved ejection fraction develop increases in left ventricular (LV) end-diastolic pressures during exercise that contribute to dyspnea. In normal open-chest animal preparations, the pericardium restrains LV filling when central blood volume increases. We hypothesized that resection of the pericardium using a minimally invasive epicardial approach would mitigate the increase in LV end-diastolic pressure that develops during volume loading in normal and diseased hearts with the chest intact. Methods and Results— Invasive hemodynamic assessment was performed at baseline and after saline load before and after pericardial resection in normal canines with open (n=3) and closed chest (n=5) and in a pig model with features of human heart failure and preserved ejection fraction with sternum intact (n=4). In closed-chest animals, pericardiotomy was performed using a novel subxiphoid procedure. In both experimental preparations of normal dogs, pericardiotomy blunted the increase in LV end-diastolic pressure with saline infusion, while enhancing the saline-mediated increase in LV end-diastolic volume. With chest intact in the pig model, percutaneous pericardial resection again blunted the increase in LV end-diastolic pressure secondary to volume expansion (+4±3 versus +13±5 mm Hg; P =0.014), while enhancing the saline-mediated increase in LV end-diastolic volume (+17±1 versus +10±2 mL; P =0.016). Conclusions— This proof of concept study demonstrates that pericardial resection through a minimally invasive percutaneous approach mitigates the elevation in LV filling pressures with volume loading in both normal animals and a pig model with diastolic dysfunction. Further study is warranted to determine whether this method is safe and produces similar acute and chronic hemodynamic benefits in people with heart failure and preserved ejection fraction.

Background: Heart failure (HF) with preserved ejection fraction (HFpEF) is a heterogeneous syndrome. Phenotyping patients into pathophysiologically homogeneous groups may enable better targeting of treatment. Obesity is common in HFpEF and has many cardiovascular effects, suggesting that it may be a viable candidate for phenotyping. We compared cardiovascular structure, function, and reserve capacity in subjects with obese HFpEF, those with nonobese HFpEF, and control subjects. Methods: Subjects with obese HFpEF (body mass index ≥35 kg/m 2 ; n=99), nonobese HFpEF (body mass index <30 kg/m 2 ; n=96), and nonobese control subjects free of HF (n=71) underwent detailed clinical assessment, echocardiography, and invasive hemodynamic exercise testing. Results: Compared with both subjects with nonobese HFpEF and control subjects, subjects with obese HFpEF displayed increased plasma volume (3907 mL [3563–4333 mL] versus 2772 mL [2555–3133 mL], and 2680 mL [2380–3006 mL]; P <0.0001), more concentric left ventricular remodeling, greater right ventricular dilatation (base, 34±7 versus 31±6 and 30±6 mm, P =0.0005; length, 66±7 versus 61±7 and 61±7 mm, P <0.0001), more right ventricular dysfunction, increased epicardial fat thickness (10±2 versus 7±2 and 6±2 mm; P <0.0001), and greater total epicardial heart volume (945 mL [831–1105 mL] versus 797 mL [643–979 mL] and 632 mL [517–768 mL]; P <0.0001), despite lower N-terminal pro-B-type natriuretic peptide levels. Pulmonary capillary wedge pressure was correlated with body mass and plasma volume in obese HFpEF ( r =0.22 and 0.27, both P <0.05) but not in nonobese HFpEF ( P ≥0.3). The increase in heart volumes in obese HFpEF was associated with greater pericardial restraint and heightened ventricular interdependence, reflected by increased ratio of right- to left-sided heart filling pressures (0.64±0.17 versus 0.56±0.19 and 0.53±0.20; P =0.0004), higher pulmonary venous pressure relative to left ventricular transmural pressure, and greater left ventricular eccentricity index (1.10±0.19 versus 0.99±0.06 and 0.97±0.12; P <0.0001). Interdependence was enhanced as pulmonary artery pressure load increased ( P for interaction <0.05). Compared with those with nonobese HFpEF and control subjects, obese patients with HFpEF displayed worse exercise capacity (peak oxygen consumption, 7.7±2.3 versus 10.0±3.4 and12.9±4.0 mL/min·kg; P <0.0001), higher biventricular filling pressures with exercise, and depressed pulmonary artery vasodilator reserve. Conclusions: Obesity-related HFpEF is a genuine form of cardiac failure and a clinically relevant phenotype that may require specific treatments.

Background Soluble ST2 is a biomarker that is elevated in certain systemic inflammatory diseases. Comorbidity‐driven microvascular inflammation is postulated to play a key role in heart failure with preserved ejection fraction ( HF p EF ) pathophysiology, but data on how sST 2 relates to clinical characteristics or inflammatory conditions or biomarkers in HF p EF are limited. We sought to determine circulating levels and clinical correlates of sST 2 in HF pEF. Methods and Results At enrollment, patients (n=174) from the Phosphodiesterase‐5 Inhibition to Improve Clinical Status And Exercise Capacity in Diastolic Heart Failure (RELAX) trial of sildenafil in HF p EF had sST 2 levels measured. Clinical characteristics; cardiac structure and function; exercise performance; and biomarkers of neurohumoral activation, systemic inflammation and fibrosis, and myocardial necrosis were assessed in relation to sST 2 levels. Median sST 2 levels in male and female HFpEF patients were 36.7 ng/mL (range 30.9–49.2 ng/mL; reference range 4–31 ng/mL) and 30.8 ng/mL (range 25.3–39.3 ng/mL; reference range 2–21 ng/mL), respectively. Among HF p EF patients, higher sST 2 levels were associated with the presence of diabetes mellitus; atrial fibrillation; renal dysfunction; right ventricular pressure overload and dysfunction; systemic congestion; exercise intolerance; and biomarkers of systemic inflammation and fibrosis, neurohumoral activation, and myocardial necrosis ( P <0.05 for all). sST 2 was not associated with left ventricular structure or left ventricular systolic or diastolic function. Conclusions In HF p EF , sST 2 levels were associated with proinflammatory comorbidities, right ventricular pressure overload and dysfunction, and systemic congestion but not with left ventricular geometry or function. These data suggest that sST2 may be a marker of systemic inflammation in HF p EF and potentially of extracardiac origin. Clinical Trial Registration URL : http://www.clinicaltrials.gov . Unique identifier: NCT 00763867.