The Design and Rationale of a Phase 2b, Randomized, Double-Blinded, and Placebo-Controlled Trial to Evaluate the Safety and Efficacy of Lomecel-B in Older Adults with Frailty.

BACKGROUND: Frailty in older adults is a rapidly growing unmet medical need. It is an aging-related syndrome characterized by physical decline leading to higher risk of adverse health outcomes. OBJECTIVES: To evaluate the efficacy of Lomecel-B, an allogeneic medicinal signaling cell (MSC) formulation, in older adults with frailty. DESIGN: This multicenter, randomized, parallel-arm, double-blinded, and placebo-controlled phase 2b trial is designed to evaluate dose-range effects of Lomecel-B for frailty on physical functioning, patient-reported outcomes (PROs), frailty status, and biomarkers. SETTING: Eight enrolling clinical research centers, including the Miami Veterans Affairs Medical Center. PARTICIPANTS: Target enrollment is 150 subjects aged 70-85 years of any race, ethnicity, or gender. Enrollment criteria include a Clinical Frailty Score of 5 ("mild") or 6 ("moderate"), a 6MWT of 200-400 m, and serum tumor necrosis factor-alpha (TNF-α) ≥2.5 pg/mL. INTERVENTION: A single intravenous infusion of Lomecel-B (25, 50, 100, or 200 million cells) or placebo (N=30/arm). Patients are followed for 365 days for safety, and the efficacy assessments performed at 90, 180, and 270 days. MEASUREMENTS: The primary endpoint is change in 6MWT in the Lomecel-B-treated arms versus placebo at 180 days post-infusion. Secondary and exploratory endpoints include change in: 6MWT and other physical function measures at all time points; PROs; frailty status; cognitive status; and an inflammatory biomarkers panel. A pre-specified sub-study examines vascular/endothelial biomarkers. Safety is evaluated throughout the trial. RESULTS: The trial is conducted under a Food and Drug Administration Investigational New Drug (IND), with Institutional Review Board approval, and monitoring by an NIH-appointed independent Data Safety Monitoring Board. CONCLUSION: This clinical trial investigates the use of a regenerative medicine strategy for frailty in older adults. The results will further the understanding of the potential for Lomecel-B in the geriatric condition of frailty.

Utility of exercise testing to assess athletes for post COVID-19 myocarditis.

Purpose: This study assessed a functional protocol to identify myocarditis or myocardial involvement in competitive athletes following SARS-CoV2 infection. Methods: We prospectively evaluated competitive athletes (n = 174) for myocarditis or myocardial involvement using the Multidisciplinary Inquiry of Athletes in Miami (MIAMI) protocol, a median of 18.5 (IQR 16-25) days following diagnosis of COVID-19 infection. The protocol included biomarker analysis, ECG, cardiopulmonary stress echocardiography testing with global longitudinal strain (GLS), and targeted cardiac MRI for athletes with abnormal findings. Patients were followed for median of 148 days. Results: We evaluated 52 females and 122 males, with median age 21 (IQR: 19, 22) years. Five (2.9%) had evidence of myocardial involvement, including definite or probable myocarditis (n = 2). Three of the 5 athletes with myocarditis or myocardial involvement had clinically significant abnormalities during stress testing including ventricular ectopy, wall motion abnormalities and/or elevated VE/VCO2, while the other two athletes had resting ECG abnormalities. VO2max, left ventricular ejection fraction and GLS were similar between those with or without myocardial involvement. No adverse events were reported in the 169 athletes cleared to exercise at a median follow-up of 148 (IQR108,211) days. Patients who were initially restricted from exercise had no adverse sequelae and were cleared to resume training between 3 and 12 months post diagnosis. Conclusions: Screening protocols that include exercise testing may enhance the sensitivity of detecting COVID-19 related myocardial involvement following recovery from SARS-CoV2 infection.

The physiological response to cardiovascular 'orphan' G protein-coupled receptor agonists.

Cardiac pressor agents typically reduce the amount of blood pumped with each heartbeat. Cardiovascular hemodynamic principles can show whether such a response is physiologic or maladaptive.

ICFSR Task Force Perspective on Biomarkers for Sarcopenia and Frailty.

Biomarkers of frailty and sarcopenia are essential to advance the understanding of these conditions of aging and develop new diagnostic tools and effective treatments. The International Conference on Frailty and Sarcopenia Research (ICFSR) Task Force - a group of academic and industry scientists from around the world -- met in February 2019 to discuss the current state of biomarker development for frailty and sarcopenia. The D3Cr dilution method, which assesses creatinine excretion as a biochemical measure of muscle mass, was suggested as a more accurate measure of functional muscle mass than assessment by dual energy x-ray absorptiometry (DXA). Proposed biomarkers of frailty include markers of inflammation, the hypothalamic-pituitary-adrenal (HPA) axis response to stress, altered glucose insulin dynamics, endocrine dysregulation, aging, and others, acknowledging the complex multisystem etiology that contributes to frailty. Lack of clarity regarding a regulatory pathway for biomarker development has hindered progress; however, there are currently several international efforts to develop such biomarkers as tools to improve the treatment of individuals presenting these conditions.

Designing Drug Trials for Frailty: ICFSR Task Force 2018.

To reduce disability and dependence in older adults, frailty may represent an appropriate target for intervention. While preventing frailty through lifestyle interventions may be the optimal public health approach for many population groups, pharmacological approaches will likely be needed for individuals who meet frailty criteria or who have comorbid conditions that contribute to and complicate the frailty syndrome, and for those who are not compliant with lifestyle interventions. Barriers to successful development of drug treatments for frailty include variability in how the frailty syndrome is defined, lack of agreement on the best diagnostic tools and outcome measures, and the paucity of sensitive, reliable, and validated biomarkers. The International Conference on Frailty and Sarcopenia Research Task Force met in Miami, Florida, on February 28, 2018, to consider the status of treatments under development for frailty and discuss potential strategies for advancing the field. They concluded that at the present time, there may be a more productive regulatory pathway for adjuvant treatments or trials targeting specific functional outcomes such as gait speed. They also expressed optimism that several studies currently underway may provide the insight needed to advance drug development for frailty.

beta(3)-adrenoceptor deficiency blocks nitric oxide-dependent inhibition of myocardial contractility.

The cardiac beta-adrenergic pathway potently stimulates myocardial performance, thereby providing a mechanism for myocardial contractile reserve. beta-Adrenergic activation also increases cardiac nitric oxide (NO) production, which attenuates positive inotropy, suggesting a possible negative feedback mechanism. Recently, in vitro studies suggest that stimulation of the beta(3)-adrenoceptor results in a negative inotropic effect through NO signaling. In this study, using mice with homozygous beta(3)-adrenoceptor deletion mutations, we tested the hypothesis that the beta(3)-adrenoceptor is responsible for beta-adrenergic activation of NO. Although resting indices of myocardial contraction were similar, beta-adrenergic-stimulated inotropy was increased in beta(3)(-/-) mice, and similar hyper-responsiveness was seen in mice lacking endothelial NO synthase (NOS3). NOS inhibition augmented isoproterenol-stimulated inotropy in wild-type (WT), but not in beta(3)(-/-) mice. Moreover, isoproterenol increased myocardial cGMP in WT, but not beta(3)(-/-), mice. NOS3 protein abundance was not changed in beta(3)(-/-) mice, and cardiac beta(3)-adrenoceptor mRNA was detected in both NOS3(-/-) and WT mice. These findings indicate that the beta(3)-adrenergic subtype participates in NO-mediated negative feedback over beta-adrenergic stimulation.

Role of nitric oxide in parasympathetic modulation of beta-adrenergic myocardial contractility in normal dogs.

In vitro studies indicate that muscarinic cholinergic inhibition of beta-adrenergic cardiac responses may be modulated in part by nitric oxide (NO). To evaluate the role of NO in parasympathetic inhibition of the beta-adrenergic contractile response in vivo, we assessed the inotropic response to dobutamine before and during bilateral vagus nerve stimulation in closed-chest dogs. Dobutamine administration and vagal stimulation were repeated during intracoronary infusion of the NO synthase inhibitor NG-monomethyl-L-arginine (L-NMMA, 10 mumol/min) and again following infusion of L-arginine (100 mg/kg). In eight dogs, intracoronary dobutamine infusion at rates of 25 and 50 micrograms/min increased peak +dP/dt by 131 +/- 24 and 168 +/- 22%, respectively (P < 0.0001). Vagal stimulation (2.5 Hz) attenuated the responses to dobutamine (25 and 50 micrograms/min) by 23 +/- 4 and 21 +/- 4%, respectively (P < 0.001). L-NMMA reduced (by 44-62%; P < 0.001) and L-arginine restored vagal inhibition of the dobutamine-stimulated inotropic response. In a second group of nine dogs, dobutamine was administered systemically to assure a constant concentration in the coronary circulation. Vagal stimulation (2.5 Hz) attenuated the dobutamine-stimulated inotropic response (2.5 and 5.0 micrograms/kg per min) by 40 +/- 12% and 57 +/- 8%, respectively (P < 0.004). As with intracoronary dobutamine, L-NMMA diminished and L-arginine restored vagal inhibition of the inotropic response to dobutamine. Intracoronary infusion of atropine (12 micrograms/min) abolished the vagal inhibitory effect, and intracoronary infusion of 8-bromo-cyclic GMP (1 and 10 mM) caused a dose-dependent attenuation of the dobutamine-stimulated increase in +dP/dt. These data suggest that NO mediates, at least in part, vagal inhibition of the inotropic response to beta-adrenergic stimulation by dobutamine, and thus may play a role in normal physiologic regulation of myocardial autonomic responses.

Pertussis toxin-sensitive G proteins influence nitric oxide synthase III activity and protein levels in rat heart.

Inhibitory G protein activity (Gi) and nitric oxide (NO) modulate muscarinic-cholinergic (MC) inhibition of cardiac beta-adrenergic inotropic responses. We hypothesized that Gi mediates MC-NO synthase (NOS) signal transduction. Isoproterenol (0.2-0.8 microg/min) and acetylcholine (1 microM) were administered to isolated perfused rat hearts pretreated with saline (controls; n = 8) or pertussis toxin (PT; 30 microg/kg intraperitoneally 3 d before study; n = 20). PT abrogated in vitro ADP-ribosylation of Gi protein alpha subunit(s) indicating near-total decrease in Gi protein function. Isoproterenol increased peak +dP/dt in both control (peak isoproterenol effect: +2, 589+/-293 mmHg/s, P < 0.0001) and PT hearts (+3,879+/-474 mmHg/s, P < 0.0001). Acetylcholine reversed isoproterenol inotropy in controls (108+/-21% reduction of +dP/dt response, P = 0.001), but had no effect in PT hearts. In controls, NG-monomethyl-L-arginine (100 microM) reduced basal +dP/dt, augmented isoproterenol +dP/dt (peak effect: +4,634+/-690 mmHg/s, P < 0.0001), and reduced the MC inhibitory effect to 69+/-8% (P < 0.03 vs. baseline). L-arginine (100 M) had no effect in controls but in PT hearts decreased basal +dP/dt by 1, 426+/-456 mmHg/s (P < 0.005), downward-shifted the isoproterenol concentration-effect curve, and produced a small MC inhibitory effect (27+/-4% reduction, P < 0.05). This enhanced response to NO substrate was associated with increased NOS III protein abundance, and a three- to fivefold increase in in vitro calcium-dependent NOS activity. Neomycin (1 microM) inhibition of phospholipase C did not reverse L-arginine enhancement of MC inhibitory effects. These data support a primary role for Gi in MC receptor signal transduction with NOS in rat heart, and demonstrate regulatory linkage between Gi and NOS III protein levels.

Interaction between neuronal nitric oxide synthase and inhibitory G protein activity in heart rate regulation in conscious mice.

Nitric oxide (NO) synthesized within mammalian sinoatrial cells has been shown to participate in cholinergic control of heart rate (HR). However, it is not known whether NO synthesized within neurons plays a role in HR regulation. HR dynamics were measured in 24 wild-type (WT) mice and 24 mice in which the gene for neuronal NO synthase (nNOS) was absent (nNOS-/- mice). Mean HR and HR variability were compared in subsets of these animals at baseline, after parasympathetic blockade with atropine (0.5 mg/kg i.p.), after beta-adrenergic blockade with propranolol (1 mg/kg i.p.), and after combined autonomic blockade. Other animals underwent pressor challenge with phenylephrine (3 mg/kg i.p.) after beta-adrenergic blockade to test for a baroreflex-mediated cardioinhibitory response. The latter experiments were then repeated after inactivation of inhibitory G proteins with pertussis toxin (PTX) (30 microgram/kg i.p.). At baseline, nNOS-/- mice had higher mean HR (711+/-8 vs. 650+/-8 bpm, P = 0.0004) and lower HR variance (424+/-70 vs. 1,112+/-174 bpm2, P = 0.001) compared with WT mice. In nNOS-/- mice, atropine administration led to a much smaller change in mean HR (-2+/-9 vs. 49+/-5 bpm, P = 0.0008) and in HR variance (64+/-24 vs. -903+/-295 bpm2, P = 0.02) than in WT mice. In contrast, propranolol administration and combined autonomic blockade led to similar changes in mean HR between the two groups. After beta-adrenergic blockade, phenylephrine injection elicited a fall in mean HR and rise in HR variance in WT mice that was partially attenuated after treatment with PTX. The response to pressor challenge in nNOS-/- mice before PTX administration was similar to that in WT mice. However, PTX-treated nNOS-/- mice had a dramatically attenuated response to phenylephrine. These findings suggest that the absence of nNOS activity leads to reduced baseline parasympathetic tone, but does not prevent baroreflex-mediated cardioinhibition unless inhibitory G proteins are also inactivated. Thus, neuronally derived NO and cardiac inhibitory G protein activity serve as parallel pathways to mediate autonomic slowing of heart rate in the mouse.

Mesenchymal stem cells for cardiac regenerative therapy.

Until recently, the concept of treating the injured or failing heart by generating new functional myocardium was considered physiologically impossible. Major scientific strides in the past few years have challenged the concept that the heart is a post-mitotic organ, leading to the hypothesis that cardiac regeneration could be therapeutically achieved. Bone marrow-derived adult stem cells were among the first cell populations that were used to test this hypothesis. Animal studies and early clinical experience support the concept that therapeutically delivered mesenchymal stem cells (MSCs) safely improve heart function after an acute myocardial infarction (MI). MSCs produce a variety of cardio-protective signalling molecules, and have the ability to differentiate into both myocyte and vascular lineages. Additionally, MSCs are attractive as a cellular vehicle for gene delivery, cell transplantation or for tissue engineering because they offer several practical advantages. They can be obtained in relatively large numbers through standard clinical procedures, and they are easily expanded in culture. The multi-lineage potential of MSC, in combination with their immunoprivileged status, make MSCs a promising source for cell therapy in cardiac diseases. Here we provide an overview of biological characteristics of MSCs, experimental animal studies and early clinical trials with MSCs. In addition, we discuss the routes of cell delivery, cell tracking experiments and current knowledge of the mechanistic underpinnings of their action.

Upregulation of the nitric oxide-cGMP pathway in aged myocardium: physiological response to l-arginine.

Cardiovascular aging is associated with decreased endothelial vasoreactivity and prolonged diastolic relaxation. As diminished NO signaling contributes to age-associated endothelial dysfunction, we tested the hypothesis that impaired NO signaling or bioactivity also contributes to slowed ventricular relaxation with age. Accordingly, we measured myocardial NO synthase (NOS) enzyme activity, protein abundance, and cGMP production in old (22 to 25 months) and young adult (4 to 7 months) male Wistar rats. Both NOS3 protein abundance and calcium-dependent NOS activity were elevated in old compared with young adult hearts (7.2+/-1.1 versus 4.2+/-0.6 pmol/mg protein, respectively, P=0.03). However, NOS activity and protein abundance were similar in isolated myocytes, indicating that endothelial NOS likely explains the age difference. Cardiac effluent cGMP (enzyme immunoassay) was 4.8-fold higher (1794+/-373 fmol/min per mg heart tissue) in older versus younger hearts (P=0.003). To assess NO pathway responsiveness, we administered the NOS substrate l-arginine (100 micrometer) to isolated perfused rat hearts. Baseline isovolumic relaxation (tau) was prolonged in old (42.9+/-2.5 ms, n=16) versus young hearts (36.0+/-1.9 ms, n=11, P=0.03). l-Arginine decreased tau (P<0.001) and left ventricular end-diastolic pressure in both old and young hearts. Supporting an NO/cGMP-mediating mechanism, the NO donor sodium nitroprusside reduced tau (maximal effect, -14+/-2%, n=5, P<0.001), and this lusitropic effect was attenuated by the soluble guanylyl cyclase inhibitor 1H:-[1,2,4]oxadiazolo-[4,3,-a]quinoxalin-1-one (n=7, P<0.001). Thus, the NO-cGMP pathway is upregulated in the endothelial cells of aged hearts. l-Arginine, the NOS precursor, enhances ventricular relaxation in old and young hearts, indicating that the NOS pathway may be exploited to modulate diastolic function in aged myocardium.

Contribution of caveolin protein abundance to augmented nitric oxide signaling in conscious dogs with pacing-induced heart failure.

Myocardial NO signaling appears elevated in heart failure (HF). Whether this results from increased NO production, induction of the high-output NO synthase (NOS)2 isoform, or changes in NOS regulatory pathways (such as caveolae) remains controversial. We tested the hypothesis that increased abundance of caveolin-3 and/or sarcolemmal caveolae contribute to increased NO signaling in pacing-induced HF. Abundance of caveolin-3 (0.59+/-0.08 versus 0.29+/-0.08 arbitrary units, P = 0.01) but not caveolin-1 was increased in HF compared with control conditions, assessed by Western blot. Additionally, transmission electron microscopy revealed increased caveolae (2. 7+/-0.4 versus 1.3+/-0.3 per micrometer myocyte membrane, P<0.005). The association between caveolin-3 and NOS3 at the sarcolemma and T tubules was unchanged in HF compared with control myocytes. The impact of NOS inhibition with L-N(G)-methylarginine hydrochloride (L-NMMA) on beta-adrenergic inotropy was assessed in conscious dogs before and after HF. In control dogs, dobutamine (5 microg. kg(-1) x min(-1)) increased +dP/dt by 36+/-7%, and this was augmented to 66+/-24% by 20 mg/kg L-NMMA (P = 0.04 versus without L-NMMA, n = 8) but not affected by 10 mg/kg L-NMMA (34+/-10%, P = NS; n = 8). In HF, dobutamine +dP/dt response was depressed (P<0.001 versus control), and increased concentrations were required to match control inotropic responses (10 to 15 microg. kg(-1) x min(-1), 48+/-7%). L-NMMA enhanced +dP/dt responses similarly at 10 mg/kg (61+/-17%, P = 0.02; n = 4) and 20 mg/kg (54+/-7%, P = 0.04; n = 7). Caveolin-3 abundance positively correlated with L-NMMA augmentation of dobutamine inotropic responses in HF (r = 0.9, P = 0.03; n = 4). Thus, in canine pacing-induced HF, expression of caveolin-3 and of sarcolemmal caveolae is increased. This increase is associated with augmented agonist-stimulated NO signaling, likely via a compartmentation effect.

Improved mechanoenergetics and cardiac rest and reserve function of in vivo failing heart by calcium sensitizer EMD-57033.

BACKGROUND: Myofilament Ca(2+) sensitizers enhance contractility but can adversely alter diastolic function through sensitization to low intracellular Ca(2+) concentration. Concomitant phosphodiesterase III inhibition (PDE3I) may offset diastolic changes but limit the mechanoenergetic benefits. We tested whether selective Ca(2+) sensitization in vivo with the use of EMD-57033 enhances both systolic and diastolic function in failing hearts at minimal energetic cost. METHODS AND RESULTS: Pressure-dimension data were measured with sonomicrometry/micromanometry in conscious dogs before (CON, n=9) and after tachycardia-induced heart failure (HF, n=11). In contrast to blunted dobutamine (DOB) responses in HF, low-dose EMD-57033 (0.4 mg. kg(-1). min(-1) for 20 minutes) markedly enhanced contractility, doubling end-systolic elastance and raising fractional shortening similarly in CON-treated and HF hearts. EMD-57033 effects were achieved at a reduced heart rate, without vasodilation. EMD-57033 augmented blunted heart rate-dependent contractility responses in HF at a rate of twice that of DOB, despite matched basal inotropic responses. EMD-57033 also improved diastolic function, lowering left ventricular end-diastolic pressure and increasing the filling rate. At equipotent inotropic doses and matched preload, EMD-57033 lowered the oxygen cost of contractility by -11.4+/-5.8%, whereas it rose 64+/-18% with DOB (P=0.001) and 28+/-11% with milrinone. Doubling EMD-57033 dose further augmented positive inotropy in CON and HF, accompanied by vasodilation, increased heart rate, and other changes consistent with PDE3I coactivity, but the oxygen cost of contractility remained improved compared with the use of DOB. CONCLUSIONS: Selective Ca(2+) sensitization with minimal PDE3I in vivo is achieved with the use of EMD-57033, improving basal and rate-stimulated contractility and mechanoenergetics of HF without compromising diastolic function. Despite PDE3I activity at higher doses, energetic benefits persist.

Left ventricular or biventricular pacing improves cardiac function at diminished energy cost in patients with dilated cardiomyopathy and left bundle-branch block.

BACKGROUND: Left ventricular or biventricular pacing/stimulation can acutely improve systolic function in patients with dilated cardiomyopathy (DCM) and intraventricular conduction delay by resynchronizing contraction. Most heart failure therapies directly enhancing systolic function do so while concomitantly increasing myocardial oxygen consumption (MVO(2)). We hypothesized that pacing/stimulation, in contrast, incurs systolic benefits without raising energy demand. METHODS AND RESULTS: Ten DCM patients with left bundle-branch block (ejection fraction 20+/-3%, QRS duration 179+/-3 ms, mean+/-SEM) underwent cardiac catheterization to measure ventricular and aortic pressure, coronary blood flow, arterial-coronary sinus oxygen difference (DeltaAVO(2)), and MVO(2). Data were measured under sinus rhythm or with left ventricular or biventricular pacing/stimulation at the same heart rate. These results were then contrasted to intravenous dobutamine (n=7) titrated to match systolic changes during LV pacing. Systolic function rose quickly and substantially from LV pacing (18+/-4% rise in arterial pulse pressure, which correlates with cardiac output, and 43+/-6% increase in dP/dt(max); both P<0.01). However, DeltaAVO(2) and MVO(2) declined -4+/-2% and -8+/-6.5%, respectively (both P<0.05). Similar results were obtained with biventricular activation. In contrast, dobutamine raised dP/dt(max) 37+/-6%, accompanied by a 22+/-11% rise in per-beat MVO(2) (P<0.05 versus pacing). CONCLUSIONS: Ventricular resynchronization by left ventricular or biventricular pacing/stimulation in DCM patients with left bundle-branch block acutely enhances systolic function while modestly lowering energy cost. This should prove valuable for treating DCM patients with basal dyssynchrony.

Allopurinol improves myocardial efficiency in patients with idiopathic dilated cardiomyopathy.

BACKGROUND: Dilated cardiomyopathy is characterized by an imbalance between left ventricular performance and myocardial energy consumption. Experimental models suggest that oxidative stress resulting from increased xanthine oxidase (XO) activity contributes to this imbalance. Accordingly, we hypothesized that XO inhibition with intracoronary allopurinol improves left ventricular efficiency in patients with idiopathic dilated cardiomyopathy. METHODS AND RESULTS: Patients (n=9; ejection fraction, 29+/-3%) were instrumented to assess myocardial oxygen consumption (MVO(2)), peak rate of rise of left ventricular pressure (dP/dt(max)), stroke work (SW), and efficiency (dP/dt(max)/MV O(2) and SW/MVO(2)) at baseline and after sequential infusions of intracoronary allopurinol (0.5, 1.0, and 1.5 mg/min, each for 15 minutes). Allopurinol caused a significant decrease in MVO(2) (peak effect, -16+/-5%; P<0.01; n=9) with no parallel decrease in dP/dt(max) or SW and no change in ventricular load. The net result was a substantial improvement in myocardial efficiency (peak effects: dP/dt(max)/MVO(2), 22+/-9%, n=9; SW/MVO(2), 40+/-17%, n=6; both P<0.05). These effects were apparent despite concomitant treatment with standard heart failure therapy, including ACE inhibitors and beta-blockers. XO and its parent enzyme xanthine dehydrogenase were more abundant in failing explanted human myocardium on immunoblot. CONCLUSIONS: These findings indicate that XO activity may contribute to abnormal energy metabolism in human cardiomyopathy. By reversing the energetic inefficiency of the failing heart, pharmacological XO inhibition represents a potential novel therapeutic strategy for the treatment of human heart failure.

Acute endothelin A receptor blockade causes selective pulmonary vasodilation in patients with chronic heart failure.

BACKGROUND: Elevated plasma endothelin-1 (ET-1) levels in patients with chronic heart failure correlate with pulmonary artery pressures and pulmonary vascular resistance. ET(A) receptors on vascular smooth muscle cells mediate pulmonary vascular contraction and hypertrophy. We determined the acute hemodynamic effects of sitaxsentan, a selective ET(A) receptor antagonist, in patients with chronic stable heart failure receiving conventional therapy. METHODS AND RESULTS: This multicenter, double-blind, placebo-controlled trial enrolled 48 patients with chronic New York Heart Association functional class III or IV heart failure (mean left ventricular ejection fraction 21+/-1%) treated with ACE inhibitors and diuretics. Patients with a baseline pulmonary capillary wedge pressure >/=15 mm Hg and a cardiac index

Effect of baseline or changes in adrenergic activity on clinical outcomes in the beta-blocker evaluation of survival trial.

BACKGROUND: Adrenergic activation is thought to be an important determinant of outcome in subjects with chronic heart failure (CHF), but baseline or serial changes in adrenergic activity have not been previously investigated in a large patient sample treated with a powerful antiadrenergic agent. METHODS AND RESULTS: Systemic venous norepinephrine was measured at baseline, 3 months, and 12 months in the beta-Blocker Evaluation of Survival Trial (BEST), which compared placebo treatment with the beta-blocker/sympatholytic agent bucindolol. Baseline norepinephrine level was associated with a progressive increase in rates of death or death plus CHF hospitalization that was independent of treatment group. On multivariate analysis, baseline norepinephrine was also a highly significant (P<0.001) independent predictor of death. In contrast, the relation of the change in norepinephrine at 3 months to subsequent clinical outcomes was complex and treatment group-dependent. In the placebo-treated group but not in the bucindolol-treated group, marked norepinephrine increase at 3 months was associated with increased subsequent risks of death or death plus CHF hospitalization. In the bucindolol-treated group but not in the placebo-treated group, the 1st quartile of marked norepinephrine reduction was associated with an increased mortality risk. A likelihood-based method indicated that 18% of the bucindolol group but only 1% of the placebo group were at an increased risk for death related to marked reduction in norepinephrine at 3 months. CONCLUSIONS: In BEST, a subset of patients treated with bucindolol had an increased risk of death as the result of sympatholysis, which compromised the efficacy of this third-generation beta-blocker.

Complications of transvenous right ventricular endomyocardial biopsy in adult patients with cardiomyopathy: a seven-year survey of 546 consecutive diagnostic procedures in a tertiary referral center.

To determine the incidence, nature and subsequent management of complications occurring during right ventricular endomyocardial biopsy in patients with cardiomyopathy, all events occurring during 546 procedures in 464 consecutive patients were prospectively recorded. The internal jugular vein was the primary site of introduction in 96% of cases. A total of 33 complications (6%) occurred: 15 (2.7%) during catheter insertion including 12 arterial punctures (2%), 2 vasovagal reactions (0.4%) and 1 episode of prolonged bleeding (0.2%), all without sequelae; 18 (3.3%) during biopsy included 6 arrhythmias (1.1%), 5 conduction abnormalities (1%), 4 possible perforations (0.7%) and 3 definite perforations (0.5%) (pericardial fluid). Two (0.4%) of the three patients with a perforation died. There was no secular trend in the complication rate, nor were complications associated with specific clinical or hemodynamic characteristics. It is concluded that the overall rate of endomyocardial biopsy complications (6%) is low, but mortality may occur.

Effect of bolus milrinone on hemodynamic variables and pulmonary vascular resistance in patients with severe left ventricular dysfunction: a rapid test for reversibility of pulmonary hypertension.

OBJECTIVES: To examine the feasibility of using milrinone to test pulmonary vascular reactivity in patients before heart transplantation, we tested the hypothesis that milrinone would lower pulmonary vascular resistance (PVR) in patients with severe heart failure. BACKGROUND: Fixed pulmonary hypertension is a risk factor for right heart failure and death after orthotopic heart transplantation. Sodium nitroprusside, the agent used most commonly to test for reversibility of pulmonary hypertension before transplantation, requires dose titration and is frequently limited by hypotension. Milrinone is an intravenously active phosphodiesterase inhibitor that acts rapidly and exerts both positive inotropic and direct vasodilator effects in patients with heart failure. The ability of milrinone to lower PVR in patients with heart failure has not been tested. METHODS: In 27 patients with New York Heart Association functional class III or IV heart failure referred for heart transplantation with a PVR > or = 200 dynes-s-cm-5, we measured the hemodynamic response to a single intravenous bolus of milrinone (50 micrograms/kg body weight) infused over 1 min. RESULTS: Milrinone decreased PVR in all patients. The effect was maximal 5 to 10 min after the bolus and persisted for at least 20 min. The reduction in PVR at 5 min ([mean +/- SEM] 31 +/- 4%) was associated with a 42 +/- 4% increase in cardiac output and decreases of 12 +/- 4% and 16 +/- 5% in mean pulmonary artery and pulmonary artery wedge pressures, respectively, but no change in transpulmonary pressure gradient. Milrinone had no effect on heart rate or systemic arterial pressure. The magnitude of the decrease in PVR correlated inversely with the milrinone-induced increase in cardiac output. CONCLUSIONS: Bolus milrinone consistently decreases PVR in patients with pulmonary hypertension secondary to severe heart failure. This effect is rapid in onset and well tolerated, even by patients with low systemic arterial pressure. An intravenous bolus of milrinone can be used to test for the reversibility of pulmonary hypertension in patients with heart failure undergoing evaluation for heart transplantation.