Borlaug, Barry A.

Background— Early studies showed beneficial effects of phosphodiesterase 5 inhibitors on cardiovascular function in heart failure (HF) patients, but the RELAX trial observed no improvement in exercise capacity with sildenafil treatment in subjects with HF and preserved ejection fraction. Methods and Results— A subgroup of participants in the RELAX trial (n=48) underwent comprehensive noninvasive cardiovascular assessment before and after treatment with sildenafil or placebo in a prospective ancillary study. Left ventricular contractility was assessed by peak power index and stroke work index. Systemic arterial load was assessed by arterial elastance (Ea) and right ventricular afterload by pulmonary artery systolic pressure. Endothelial function was assessed by reactive hyperemia index after upper arm cuff occlusion. Compared with placebo (n=25), sildenafil (n=23) decreased Ea (−0.29±0.28 mm Hg/mL versus +0.02±0.29, P =0.008) and tended to improve reactive hyperemia index (+0.30±0.45 versus −0.17±0.30, P =0.054). In contrast, left ventricular contractility was reduced by 11% to 16% with sildenafil compared with placebo (ΔPWR/EDV −52±70 versus +0±40 mm Hg/s, P =0.006; ΔSW/EDV +0.3±5.8 versus −6.0±5.1 mm Hg, P =0.04). Sildenafil had no effect on pulmonary artery systolic pressure. Conclusions— In subjects with HF and preserved ejection fraction, sildenafil displayed opposing effects on ventricular and vascular function. We speculate that beneficial effects of phosphodiesterase 5 inhibitors in the systemic vasculature and endothelium were insufficient to improve clinical status or that the deleterious effects on left ventricular function offset any salutary vascular effects, contributing to the absence of benefit observed with sildenafil in subjects with HF and preserved ejection fraction in the RELAX trial. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT00094302.

Background— Left atrial (LA) structure and function are altered in most heart failure (HF) patients, but there may be fundamental differences in LA properties between HF with preserved (HFpEF) and reduced ejection fraction (HFrEF). Methods and Results— One hundred ninety-eight HF patients (51% HFpEF, New York Heart Association 3.1±0.7) and 40 HF-free controls underwent catheterization, echocardiography, and follow-up. Compared with controls, HF patients had larger and more dysfunctional left atria. At identical mean LA pressure (20 versus 20 mm Hg; P =0.9), HFrEF patients had larger LA volumes (LA volume index 50 versus 41 mL/m 2 ; P <0.001), whereas HFpEF patients had higher LA peak pressures, lower LA minimal pressures, higher LA stiffness (0.79 versus 0.48 mm Hg/mL; P <0.001), greater LA pulsatility (19 versus 13 mm Hg; P <0.001), and higher wall stress variations. Despite smaller LA volumes, better function, and less mitral regurgitation, HFpEF patients had more atrial fibrillation (42 versus 26%; P =0.02). LA dysfunction was associated with increased pulmonary vascular resistance and right ventricular dysfunction in both HF phenotypes. After a median follow-up of 350 days, 31 HFpEF and 28 HFrEF patients died. LA function (total LA EF) was associated with lower mortality in HFpEF (hazard ratio 0.43; 95% confidence interval, 0.2–0.9; P <0.05), but not in HFrEF. Conclusions— HFrEF is characterized by greater eccentric LA remodeling, whereas HFpEF by increased LA stiffness, which might contribute to greater atrial fibrillation burden. LA function is associated with pulmonary vascular disease and right HF in both HF phenotypes, but is associated with outcome more closely in HFpEF, supporting efforts to improve LA function in this cohort.

Background Hypertension is a frequent risk factor for the development of heart failure with preserved ejection fraction ( HFPEF ). Progressive extracellular matrix accumulation has been presumed to be the fundamental pathophysiologic mechanism that leads to the transition to impaired diastolic reserve. However, the contribution of other mechanisms affecting active and passive components of diastolic function has not been comprehensively assessed. In this study, we investigated the potential role of impaired myocardial oxygen delivery in the pathophysiology of HFPEF . Methods and Results Patients with HFPEF , those with controlled hypertension, and healthy controls underwent simultaneous right‐heart catheterization, echocardiography, and paired arterial and coronary sinus blood gas sampling at rest and during supine‐cycle ergometry. Despite a lower workload ( HFPEF vs control, hypertension: 43±8 versus 114±12, 87±14 W; P <0.001 and P <0.05, respectively), peak exercise pulmonary capillary wedge pressure was markedly higher in HFPEF patients compared with healthy and hypertensive controls (32±2 versus 16±1 and 17±1 mm Hg, both P <0.001). During exercise, the transcardiac oxygen gradient increased significantly in all groups; however, the peak transcardiac oxygen gradient was significantly lower in HFPEF patients ( P <0.05). In addition, the left ventricular–work corrected transcardiac oxygen gradient remained significantly lower in HFPEF patients compared with controls ( P <0.001). Conclusion The current study provides unique data suggesting that the abnormal diastolic reserve observed during exertion in HFPEF patients may, in part, be explained by impaired myocardial oxygen delivery due possibly to microvascular dysfunction. Further studies are required to confirm the structural and functional basis of these findings and to investigate the influence of potential therapies on this abnormality.

Abstract Aims Left ventricular systolic elastance (Ees) and diastolic elastance (Eed) correlate with arterial elastance (Ea), but it is unknown how chronic changes in arterial compliance and resistance, which determine Ea, might differentially affect cardiac properties with ageing. We sought to characterize chronic changes in pulsatile and resistive arterial load and correlate them with longitudinal changes in LV structure and function in a prospective, community-based study. Methods and results Comprehensive echocardiography was performed in 722 subjects participating in a randomly selected community-based study at two examinations separated by 4 years, allowing for assessment of LV Ees, Eed, and end-diastolic volume (EDV), Ea, total arterial compliance, and systemic vascular resistance at both examinations. Chronic changes in resistance and heart rate were the dominant contributors to change in Ea. Changes in arterial compliance had little impact on changes in Ea, but were strongly associated with changes in Ees. The combination of increased resistance and decreased compliance was associated with the largest increase in LV diastolic stiffness, an effect that was mediated by a decrease in LVEDV. In contrast, subjects with both improved arterial compliance and decreased resistance displayed an increase in LVEDV over time, with no increase in LV Eed. Conclusion Increases in pulsatile arterial load with ageing contribute more to LV systolic stiffening, while combined pulsatile and resistive loading changes are associated with positive and negative chamber remodelling and diastolic stiffness. Therapies designed to improve arterial resistance and particularly to enhance aortic compliance may hold promise to prevent or reverse cardiac ageing and its sequelae.

Background— Invasive hemodynamic exercise testing is commonly used in the evaluation of patients with suspected heart failure with preserved ejection fraction (HFpEF) or pulmonary hypertension. Saline loading has been suggested as an alternative provocative maneuver, but the hemodynamic changes induced by the 2 stresses have not been compared. Methods and Results— Twenty-six subjects (aged, 67±10 years; n=14 HFpEF; n=12 control) underwent right heart catheterization at rest, during supine exercise, and with acute saline loading in a prospective study. Exercise and saline each increased cardiac output and pressures in the right atrium, pulmonary artery, and pulmonary capillary wedge positions. Changes in heart rate, blood pressure, rate–pressure product, and cardiac output were greater with exercise compared with saline. In controls subjects, right atrial pressure, pulmonary arterial pressure, and pulmonary capillary wedge pressure increased similarly with saline and exercise, whereas in HFpEF subjects, exercise led to ≈2-fold greater increases in right atrial pressure (10±4 versus 6±3 mm Hg; P =0.02), pulmonary arterial pressure (22±8 versus 11±4 mm Hg; P =0.0001), and pulmonary capillary wedge pressure (18±5 versus 10±4 mm Hg; P <0.0001) compared with saline. Systolic reserve assessed by stroke work and cardiac power output was lower in HFpEF subjects with both exercise and saline. Systemic and pulmonary arterial compliances were enhanced with saline but reduced with exercise. Conclusions— Exercise elicits greater pulmonary capillary wedge pressure elevation compared with saline in HFpEF but not controls, suggesting that hemodynamic stresses beyond passive stiffness and increased venous return explain the development of pulmonary venous hypertension in HFpEF. Exercise testing is more sensitive than saline loading to detect hemodynamic derangements indicative of HFpEF. Clinical Trial Registration— URL: http://www.clinicaltrials.gov . Unique identifier: NCT01418248.

Background— Patients with severe tricuspid regurgitation (TR) frequently present with exertional fatigue and dyspnea, but the hemodynamic basis for exercise limitation in people with TR remains unclear. Methods and Results— Twelve subjects with normal left ventricular (LV) ejection fraction and grade ≥3 TR underwent high-fidelity invasive hemodynamic exercise testing with simultaneous expired gas analysis and were compared with 13 age- and sex-matched controls. At rest, TR subjects had lower pulmonary blood flow (3.6±0.4 versus 5.1±1.9 L/min; P =0.01), increased right atrial pressure (12±5 versus 4±1 mm Hg; P =0.0002), and higher pulmonary capillary wedge pressure (17±5 versus 9±3 mm Hg; P =0.0001). However, LV transmural pressure (pulmonary capillary wedge pressure−right atrial pressure), which reflects LV preload independent of right heart congestion and pericardial restraint, was similar in TR and controls (6±3 versus 4±2 mm Hg; P =0.3). With exercise, TR subjects displayed lower peak V O 2 (10.3±2.8 versus 13.8±4.2 mL/min per kg; P =0.02), lower pulmonary blood flow (6.4±1.3 versus 10.3±3.3 L/min; P =0.001), and less increase in pulmonary blood flow relative to V O 2 (+4.6±1.1vs +6.2±0.7; P =0.001). TR subjects displayed higher pulmonary capillary wedge pressure with exercise, but this was solely because of RA hypertension (27±9 versus 8±3 mm Hg; P <0.0001), because LV transmural pressure dropped with exercise in subjects with TR (−5±6 versus +3±3 mm Hg; P =0.0007), suggesting inadequate LV diastolic filling, despite high pulmonary capillary wedge pressure. Conclusions— Impaired exercise capacity in people with severe TR is related to low cardiac output reserve relative to metabolic needs, coupled with elevated systemic and pulmonary venous pressures. Left heart pressures are elevated with exercise in subjects with TR, despite low LV preload, secondary to enhanced ventricular interaction.