Coronary endothelial dysfunction in patients with acute-onset idiopathic dilated cardiomyopathy

Lamin A/C Ablation Restricted to Vascular Smooth Muscle Cells, Cardiomyocytes, and Cardiac Fibroblasts Causes Cardiac and Vascular Dysfunction

Mutations in the LMNA gene (encoding lamin A/C proteins) cause several human cardiac diseases, including dilated cardiomyopathies (LMNA-DCM). The main clinical risks in LMNA-DCM patients are sudden cardiac death and progressive left ventricular ejection fraction deterioration, and therefore most human and animal studies have sought to define the mechanisms through which LMNA mutations provoke cardiac alterations, with a particular focus on cardiomyocytes. To investigate if LMNA mutations also cause vascular alterations that might contribute to the etiopathogenesis of LMNA-DCM, we generated and characterized Lmna^flox/floxSM22αCre mice, which constitutively lack lamin A/C in vascular smooth muscle cells (VSMCs), cardiac fibroblasts, and cardiomyocytes. Like mice with whole body or cardiomyocyte-specific lamin A/C ablation, Lmna^flox/floxSM22αCre mice recapitulated the main hallmarks of human LMNA-DCM, including ventricular systolic dysfunction, cardiac conduction defects, cardiac fibrosis, and premature death. These alterations were associated with elevated expression of total and phosphorylated (active) Smad3 and cleaved (active) caspase 3 in the heart. Lmna^flox/floxSM22αCre mice also exhibited perivascular fibrosis in the coronary arteries and a switch of aortic VSMCs from the 'contractile' to the 'synthetic' phenotype. Ex vivo wire myography in isolated aortic rings revealed impaired maximum contraction capacity and an altered response to vasoconstrictor and vasodilator agents in Lmna^flox/floxSM22αCre mice. To our knowledge, our results provide the first evidence of phenotypic alterations in VSMCs that might contribute significantly to the pathophysiology of some forms of LMNA-DCM. Future work addressing the mechanisms underlying vascular defects in LMNA-DCM may open new therapeutic avenues for these diseases.

TNF-α Predicts Endothelial Function and Number of CD34+ Cells after Stimulation with G-CSF in Patients with Advanced Heart Failure

Patients with advanced heart failure (HF) have reduced cardiac output and impaired peripheral blood flow, which diminishes endothelial shear stress and consequently flow-mediated dilatation (FMD). The aim of our study was to find out whether endothelial dysfunction is associated with the number of CD34+ cells and TNF-α levels in patients with ischemic and non-ischemic HF after stimulation with granulocyte colony-stimulating factor (G-CSF). We included 56 patients with advanced HF (LVEF < 35%). Eighteen patients (32.14%) had ischemic and 38 (67.86%) patients had non-ischemic HF. FMD of the brachial artery was performed before the patients underwent 5-day bone marrow stimulation with daily subcutaneous injections of G-CSF (5 μg/kg bid). On the fifth day peripheral blood CD34+ cell count was measured. No statistically significant differences were found between the patient groups in NT-proBNP levels ((1575 (425−2439) vs. 1273 (225−2239)) pg/mL; p = 0.40), peripheral blood CD34+ cell count ((67.54 ± 102.32 vs. 89.76 ± 71.21) × 106; p = 0.32), TNF-α ((8.72 ± 10.30 vs. 4.96 ± 6.16) ng/mL; p = 0.13) and FMD (6.7 ± 5.4 vs. 7.2 ± 5.9%; p = 0.76). In a linear regression model, only FMD (p = 0.001) and TNF-α (p = 0.003) emerged as statistically significant predictors of CD34+ cells counts. Our study suggests that TNF-α is a good predictor of impaired endothelial function and of CD34+ cells mobilization after G-CSF stimulation in patients with advanced HF of ischemic and non-ischemic origin.

Coronary blood flow in heart failure: cause, consequence and bystander

Heart failure is a clinical syndrome where cardiac output is not sufficient to sustain adequate perfusion and normal bodily functions, initially during exercise and in more severe forms also at rest. The two most frequent forms are heart failure of ischemic origin and of non-ischemic origin. In heart failure of ischemic origin, reduced coronary blood flow is causal to cardiac contractile dysfunction, and this is true for stunned and hibernating myocardium, coronary microembolization, myocardial infarction and post-infarct remodeling, possibly also for the takotsubo syndrome. The most frequent form of non-ischemic heart failure is dilated cardiomyopathy, caused by genetic mutations, myocarditis, toxic agents or sustained tachyarrhythmias, where alterations in coronary blood flow result from and contribute to cardiac contractile dysfunction. Hypertrophic cardiomyopathy is caused by genetic mutations but can also result from increased pressure and volume overload (hypertension, valve disease). Heart failure with preserved ejection fraction is characterized by pronounced coronary microvascular dysfunction, the causal contribution of which is however not clear. The present review characterizes the alterations of coronary blood flow which are causes or consequences of heart failure in its different manifestations. Apart from any potentially accompanying coronary atherosclerosis, all heart failure entities share common features of impaired coronary blood flow, but to a different extent: enhanced extravascular compression, impaired nitric oxide-mediated, endothelium-dependent vasodilation and enhanced vasoconstriction to mediators of neurohumoral activation. Impaired coronary blood flow contributes to the progression of heart failure and is thus a valid target for established and novel treatment regimens.

Nitric oxide — soluble guanylate cyclase — cyclic guanosine monophosphate signaling pathway in the pathogenesis of heart failure and search for novel therapeutic targets

Heart failure is a severe disease with an unfavorable prognosis, which requires intensification of therapy and the search for novel approaches to treatment. In this review, the physiological significance of soluble guanylate cyclase-related signaling pathway, reasons for decrease in its activity in heart failure and possible consequences are discussed. Pharmacological methods of stimulating the production of cyclic guanosine monophosphate using drugs with different mechanisms of action are considered. Data from clinical studies regarding their effectiveness and safety are presented. A promising approach is stimulation of soluble guanylate cyclase, which showed beneficial effects in preclinical studies, as well as in the recently completed phase III VICTORIA study.

Clinical trial in a dish using iPSCs shows lovastatin improves endothelial dysfunction and cellular cross-talk in LMNA cardiomyopathy

Mutations in LMNA, the gene that encodes lamin A and C, causes LMNA-related dilated cardiomyopathy (DCM) or cardiolaminopathy. LMNA is expressed in endothelial cells (ECs); however, little is known about the EC-specific phenotype of LMNA-related DCM. Here, we studied a family affected by DCM due to a frameshift variant in LMNA Human induced pluripotent stem cell (iPSC)-derived ECs were generated from patients with LMNA-related DCM and phenotypically characterized. Patients with LMNA-related DCM exhibited clinical endothelial dysfunction, and their iPSC-ECs showed decreased functionality as seen by impaired angiogenesis and nitric oxide (NO) production. Moreover, genome-edited isogenic iPSC lines recapitulated the EC disease phenotype in which LMNA-corrected iPSC-ECs showed restoration of EC function. Simultaneous profiling of chromatin accessibility and gene expression dynamics by combining assay for transposase-accessible chromatin using sequencing (ATAC-seq) and RNA sequencing (RNA-seq) as well as loss-of-function studies identified Krüppel-like factor 2 (KLF2) as a potential transcription factor responsible for the EC dysfunction. Gain-of-function studies showed that treatment of LMNA iPSC-ECs with KLF2 agonists, including lovastatin, rescued the EC dysfunction. Patients with LMNA-related DCM treated with lovastatin showed improvements in clinical endothelial dysfunction as indicated by increased reactive hyperemia index. Furthermore, iPSC-derived cardiomyocytes (iPSC-CMs) from patients exhibiting the DCM phenotype showed improvement in CM function when cocultured with iPSC-ECs and lovastatin. These results suggest that impaired cross-talk between ECs and CMs can contribute to the pathogenesis of LMNA-related DCM, and statin may be an effective therapy for vascular dysfunction in patients with cardiolaminopathy.

Role of endothelial dysfunction in heart failure

Coronary artery disease is a major underlying etiology for heart failure. The role of coronary microvascular disease, and endothelial dysfunction, in the pathophysiology of heart failure is poorly appreciated. Endothelial dysfunction, induced by oxidative stress, contributes to the development of heart failure. Alterations of endothelial function and nitric oxide-cyclic guanosine monophosphate (NO-cGMP) pathway are involved in the pathophysiology of heart failure with both reduced and preserved ejection fraction. Indeed, an altered endothelium dependent vasodilatation, causing repeated episodes of ischemia/reperfusion, can induce a chronic stunned myocardium with systolic dysfunction and an increased diastolic stiffness with diastolic dysfunction. Moreover, the altered NO-cGMP pathway directly affects myocardial homeostasis. Endothelial dysfunction is associated with worse prognosis and higher rate of cardiovascular events. Potential therapeutic strategies targeting the NO-cGMP pathway in patients with HF will be discussed in this review article. Although clinical data are still inconclusive, the NO-cGMP pathway represents a promising target for therapy.

Elevated plasma sRAGE and IGFBP7 in heart failure decrease after heart transplantation in association with haemodynamics

Aims

Metabolic derangement is implicated in the pathophysiology of heart failure (HF) and pulmonary hypertension (PH). We aimed to identify the dynamics of metabolic plasma proteins linked to end‐stage HF and associated PH in relation to haemodynamics, before and after heart transplantation (HT).

Methods and results

Twenty‐one metabolic plasma proteins were analysed with proximity extension assay in 20 controls and 26 patients before and 1 year after HT. Right heart catheterizations were performed in the HF patients pre‐operatively and 1 year after HT. Plasma levels of soluble receptor for advanced glycation end products (sRAGE) and insulin‐like growth factor‐binding protein 7 (IGFBP7) were higher in HF patients compared with controls (P < 0.0001) and decreased after HT (P < 0.0001), matching controls' levels. The decrease in sRAGE after HT correlated with improved mean pulmonary arterial pressure (r_s = 0.7; P < 0.0001), pulmonary arterial wedge pressure (r_s = 0.73; P < 0.0001), pulmonary vascular resistance (r_s = 0.65; P = 0.00062), and pulmonary arterial compliance (r_s = −0.52; P = 0.0074). The change in plasma IGFBP7 after HT correlated with improved mean right atrial pressure (r_s = 0.71; P = 0.00011) and N‐terminal pro‐brain natriuretic peptide (r_s = 0.71; P < 0.0001).

Conclusions

Our results indicate that plasma sRAGE may reflect passive pulmonary vascular congestion and the ‘mechanical’ state of the pulmonary vasculature in HF patients with or without related PH. Furthermore, sRAGE and IGFBP7 may provide additional insight into the pathophysiological mechanisms in HF and associated PH. Their potential clinical and therapeutic relevance in HF and associated PH need further investigation.

Reduced global myocardial perfusion reserve in DCM and HCM patients assessed by CMR-based velocity-encoded coronary sinus flow measurements and first-pass perfusion imaging

BACKGROUND

Coronary microvascular dysfunction (CMD) is an independent predictor of poor prognosis in patients suffering from dilative or hypertrophic cardiomyopathy (DCM/HCM). To assess CMD, quantitative myocardial first-pass perfusion (1P) cardiovascular magnetic resonance (CMR) can be performed. Coronary sinus flow (CSF) measurements at rest and during maximal vasodilatation are an alternative and well-validated approach for the quantification of global myocardial blood flow (MBF) in CMR.

METHODS

Global myocardial perfusion reserve (MPR) was used to compare both methods, 1P and CSF. This measure reflects the ratio of myocardial blood flow during maximal coronary vasodilatation over rest. 1P-MPR and CSF-MPR were calculated in 17 HCM patients, 14 DCM patients and 16 controls, who underwent a stress CMR study to rule out obstructive coronary artery disease. All patients were examined on a 1.5-T system and the study protocol comprised both, first-pass myocardial perfusion imaging (MPI) and velocity-encoded (VENC) phase-contrast imaging of CSF during rest and adenosine stress.

RESULTS

1P-MPR was significantly decreased only in HCM patients compared to controls (1.14 vs. 1.43, p = 0.045) whereas CSF-MPR was significantly reduced in both patient groups, HCM and DCM, compared to controls (2.38 and 2.07 vs. 3.18, p = 0.041 and p = 0.032). CSF-MBF at maximal stress was significantly lower in HCM and DCM patients compared to the control group (0.11 and 1.23 vs. 1.58 ml/min/g, p = 0.008 and p = 0.040). A moderate but significant correlation between CSF-MPR and 1P-MPR was observed (r = 0.39, p = 0.011). A negative correlation between LV wall thickness and CSF-MBF at rest and stress was found in the DCM group using VENC-based CSF measurements (r = - 0.64, p = 0.013 and r = - 0.69, p = 0.006)-but not using 1P-MPI. Post-proceeding analysis regarding 1P-MPR and CSF-MPR measurements required 20.1 and 6.5 min, respectively (p < 0.001).

CONCLUSION

The presence of microvascular disease can be non-invasively and quickly detected by VENC-based CSF-MPR measurements during routine stress perfusion CMR in both HCM and DCM patients. Compared to conventional 1P-MPI, VENC-based CSF-MPR is particularly useful in DCM patients with thinned ventricular walls.

Pathological Ace2-to-Ace enzyme switch in the stressed heart is transcriptionally controlled by the endothelial Brg1-FoxM1 complex

Genes encoding angiotensin-converting enzymes (Ace and Ace2) are essential for heart function regulation. Cardiac stress enhances Ace, but suppresses Ace2, expression in the heart, leading to a net production of angiotensin II that promotes cardiac hypertrophy and fibrosis. The regulatory mechanism that underlies the Ace2-to-Ace pathological switch, however, is unknown. Here we report that the Brahma-related gene-1 (Brg1) chromatin remodeler and forkhead box M1 (FoxM1) transcription factor cooperate within cardiac (coronary) endothelial cells of pathologically stressed hearts to trigger the Ace2-to-Ace enzyme switch, angiotensin I-to-II conversion, and cardiac hypertrophy. In mice, cardiac stress activates the expression of Brg1 and FoxM1 in endothelial cells. Once activated, Brg1 and FoxM1 form a protein complex on Ace and Ace2 promoters to concurrently activate Ace and repress Ace2, tipping the balance to Ace2 expression with enhanced angiotensin II production, leading to cardiac hypertrophy and fibrosis. Disruption of endothelial Brg1 or FoxM1 or chemical inhibition of FoxM1 abolishes the stress-induced Ace2-to-Ace switch and protects the heart from pathological hypertrophy. In human hypertrophic hearts, BRG1 and FOXM1 expression is also activated in endothelial cells; their expression levels correlate strongly with the ACE/ACE2 ratio, suggesting a conserved mechanism. Our studies demonstrate a molecular interaction of Brg1 and FoxM1 and an endothelial mechanism of modulating Ace/Ace2 ratio for heart failure therapy.

Pathogenesis and treatment of the cardiorenal syndrome: Implications of L-arginine-nitric oxide pathway impairment

A highly complex interplay exists between the heart and kidney in the setting of both normal and abnormal physiology. In the context of heart failure, a pathophysiological condition termed the cardiorenal syndrome (CRS) exists whereby dysfunction in the heart or kidney can accelerate pathology in the other organ. The mechanisms that underpin CRS are complex, and include neuro-hormonal activation, oxidative stress and endothelial dysfunction. The endothelium plays a central role in the regulation of both cardiac and renal function, and as such impairments in endothelial function can lead to dysfunction of both these organs. In particular, reduced bioavailability of nitric oxide (NO) is a key pathophysiologic component of endothelial dysfunction. The synthesis of NO by the endothelium is critically dependent on the plasmalemmal transport of its substrate, L-arginine, via the cationic amino acid transporter-1 (CAT1). Impaired L-arginine-NO pathway activity has been demonstrated individually in heart and renal failure. Recent findings suggest abnormalities of the L-arginine-NO pathway also play a role in the pathogenesis of CRS and thus this pathway may represent a potential new target for the treatment of heart and renal failure.

Acute hemodynamic effects of riociguat in patients with pulmonary hypertension associated with diastolic heart failure (DILATE-1): a randomized, double-blind, placebo-controlled, single-dose study

BACKGROUND:

Deficient nitric oxide-soluble guanylate cyclase-cyclic guanosine monophosphate signaling results from endothelial dysfunction and may underlie impaired cardiac relaxation in patients with heart failure with preserved left ventricular ejection fraction (HFpEF) and pulmonary hypertension (PH). The acute hemodynamic effects of riociguat, a novel soluble guanylate cyclase stimulator, were characterized in patients with PH and HFpEF.

METHODS:

Clinically stable patients receiving standard HF therapy with a left ventricular ejection fraction > 50%, mean pulmonary artery pressure (mPAP) ≥ 25 mm Hg, and pulmonary arterial wedge pressure (PAWP) > 15 mm Hg at rest were randomized to single oral doses of placebo or riociguat (0.5, 1, or 2 mg). The primary efficacy variable was the peak decrease in mPAP from baseline up to 6 h. Secondary outcomes included hemodynamic and echocardiographic parameters, safety, and pharmacokinetics.

RESULTS:

There was no significant change in peak decrease in mPAP with riociguat 2 mg (n = 10) vs placebo (n = 11, P = .6). However, riociguat 2 mg significantly increased stroke volume (+9 mL [95% CI, 0.4-17]; P = .04) and decreased systolic BP (−12 mm Hg [95% CI, −22 to −1]; P = .03) and right ventricular end-diastolic area (−5.6 cm² [95% CI, −11 to −0.3]; P = .04), without significantly changing heart rate, PAWP, transpulmonary pressure gradient, or pulmonary vascular resistance. Riociguat was well tolerated.

CONCLUSIONS:

In patients with HFpEF and PH, riociguat was well tolerated, had no significant effect on mPAP, and improved exploratory hemodynamic and echocardiographic parameters.

TRIAL REGISTRY:

ClinicalTrials.gov; No.: NCT01172756; URL: www.clinicaltrials.gov

Regional mapping of myocardial hibernation phenotype in idiopathic end-stage dilated cardiomyopathy

Myocardial hibernation (MH) is a well-known feature of human ischaemic cardiomyopathy (ICM), whereas its presence in human idiopathic dilated cardiomyopathy (DCM) is still controversial. We investigated the histological and molecular features of MH in left ventricle (LV) regions of failing DCM or ICM hearts. We examined failing hearts from DCM (n = 11; 41.9 ± 5.45 years; left ventricle-ejection fraction (LV-EF), 18 ± 3.16%) and ICM patients (n = 12; 58.08 ± 1.7 years; LVEF, 21.5 ± 6.08%) undergoing cardiac transplantation, and normal donor hearts (N, n = 8). LV inter-ventricular septum (IVS) and antero-lateral free wall (FW) were transmurally (i.e. sub-epicardial, mesocardial and sub-endocardial layers) analysed. LV glycogen content was shown to be increased in both DCM and ICM as compared with N hearts (P < 0.001), with a U-shaped transmural distribution (lower values in mesocardium). Capillary density was homogenously reduced in both DCM and ICM as compared with N (P < 0.05 versus N), with a lower decrease independent of the extent of fibrosis in sub-endocardial and sub-epicardial layers of DCM as compared with ICM. HIF1-α and nestin, recognized ischaemic molecular hallmarks, were similarly expressed in DCM-LV and ICM-LV myocardium. The proteomic profile was overlapping by ˜50% in DCM and ICM groups. Morphological and molecular features of MH were detected in end-stage ICM as well as in end-stage DCM LV, despite epicardial coronary artery patency and lower fibrosis in DCM hearts. Unravelling the presence of MH in the absence of coronary stenosis may be helpful to design a novel approach in the clinical management of DCM.

Heart failure in which coronary spasms played an important role

A 69-year-old woman was admitted for further examinations and treatment of chest pain. Emergency cardiac catheterization showed no significant stenosis on coronary angiograms; however, diffuse wall hypokinesis was observed on a left ventriculogram. After treating the patient's heart failure, cardiac catheterization was performed again. A spasm provocation test showed coronary spasms of the right and left coronary arteries. A right ventricular endomyocardial biopsy revealed denaturation and fibrosis of the myocardium under the endocardium, thus suggesting the presence of myocardial ischemia. This case highlights coronary spasms as a cause of heart failure.

Soluble guanylate cyclase: a potential therapeutic target for heart failure

The number of annual hospitalizations for heart failure (HF) and the mortality rates among patients hospitalized for HF remains unacceptably high. The search continues for safe and effective agents that improve outcomes when added to standard therapy. The nitric oxide (NO)-soluble guanylate cyclase (sGC)-cyclic guanosine monophosphate (cGMP) pathway serves an important physiologic role in both vascular and non-vascular tissues, including regulation of myocardial and renal function, and is disrupted in the setting of HF, leading to decreased protection against myocardial injury, ventricular remodeling, and the cardio-renal syndrome. The impaired NO-sGC-cGMP pathway signaling in HF is secondary to reduced NO bioavailability and an alteration in the redox state of sGC, making it unresponsive to NO. Accordingly, increasing directly the activity of sGC is an attractive pharmacologic strategy. With the development of two novel classes of drugs, sGC stimulators and sGC activators, the hypothesis that restoration of NO-sGC-cGMP signaling is beneficial in HF patients can now be tested. Characterization of these agents in pre-clinical and clinical studies has begun with investigations suggesting both hemodynamic effects and organ-protective properties independent of hemodynamic changes. The latter could prove valuable in long-term low-dose therapy in HF patients. This review will explain the role of the NO-sGC-cGMP pathway in HF pathophysiology and outcomes, data obtained with sGC stimulators and sGC activators in pre-clinical and clinical studies, and a plan for the further clinical development to study these agents as HF therapy.

Riociguat for patients with pulmonary hypertension caused by systolic left ventricular dysfunction: a phase IIb double-blind, randomized, placebo-controlled, dose-ranging hemodynamic study

BACKGROUND

Pulmonary hypertension caused by systolic left ventricular dysfunction is associated with significant morbidity and mortality; however, no treatment is approved for this indication. We hypothesized that riociguat, a novel soluble guanylate cyclase stimulator, would have beneficial hemodynamic effects in patients with pulmonary hypertension caused by systolic left ventricular dysfunction.

METHODS AND RESULTS

Overall, 201 patients with heart failure resulting from pulmonary hypertension caused by systolic left ventricular dysfunction were randomized to double-blind treatment with oral placebo or riociguat (0.5, 1, or 2 mg 3 times daily) for 16 weeks in 4 parallel arms. The primary outcome was the placebo-corrected change from baseline at week 16 in mean pulmonary artery pressure. Although the decrease in mean pulmonary artery pressure in the riociguat 2 mg group (-6.1±1.3 mm Hg; P<0.0001 versus baseline) was not significantly different from placebo (P=0.10), cardiac index (0.4 L·min(-1)·m(-2); 95% confidence interval, 0.2-0.5; P=0.0001) and stroke volume index (5.2 mL·m(-2); 95% confidence interval, 2.0-8.4; P=0.0018) were significantly increased without changes in heart rate or systemic blood pressure compared with placebo. Both pulmonary (-46.6 dynes·s(-1)·cm(-5); 95% confidence interval, -89.4 to -3.8; P=0.03) and systemic vascular resistance (-239.3 dynes·s(-1)·cm(-5); 95% confidence interval, -363.4 to -115.3; P=0.0002) were significantly reduced with riociguat 2 mg. Riociguat reduced the Minnesota Living With Heart Failure score (P=0.0002). Discontinuation of treatment was similar between treatment groups.

CONCLUSIONS

Although the primary end point of the study was not met, riociguat was well tolerated in patients with pulmonary hypertension caused by systolic left ventricular dysfunction and improved cardiac index and pulmonary and systemic vascular resistance.

CLINICAL TRIAL REGISTRATION

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01065454.

Elastic properties of peripheral arteries in heart failure patients in comparison with normal subjects

Understanding the change in elastic properties of peripheral arteries in heart failure patients is of particular importance, especially when compared with normal subjects. To investigate factors associated with their difference, 40 normal subjects and 60 heart failure patients were studied. Electrocardiograms, carotid pulses and radial pulses were simultaneously recorded to determine carotid-radial pulse transit time (carotid-radial PTT), arm pulse wave velocity (PWV), and arterial volume distensibility. In comparison with normal subjects, carotid-radial PTT was lower by 8 ms in heart failure patients, arm PWV higher by 1.4 m/s, and peripheral arterial distensibility lower by 0.04 % per mmHg (all significant, P < 0.01). Peripheral arterial distensibility was significantly related to systolic blood pressure (SBP) and to left ventricular ejection fraction (LVEF) for heart failure patients (both P < 0.001), but the relationship for the normal group was not statistically significant (both 0.05 < P<0.1). Ageing had a significant inverse relationship with arterial distensibility in normal subjects (P < 0.05), but not in heart failure patients (P = 0.59). No subject in the normal group had an arterial distensibility lower than 0.1 % per mmHg, in comparison with 28 % (17/60) in the heart failure group. Peripheral arterial distensibility has been shown to be significantly lower in heart failure patients in comparison with normal subjects. High SBP and low LVEF were the main factors associated with low arterial distensibility in heart failure patients.

Endothelial dysfunction, arterial stiffness, and heart failure

Outcomes for heart failure (HF) patients remain suboptimal. No known therapy improves mortality in acute HF and HF with preserved ejection fraction; the most recent HF trial results have been negative or neutral. Improvement in surrogate markers has not necessarily translated into better outcomes. To translate breakthroughs with potential therapies into clinical benefit, a better understanding of the pathophysiology establishing the foundation of benefit is necessary. Vascular function plays a central role in the development and progression of HF. Endothelial function and nitric oxide availability affect myocardial function, systemic and pulmonary hemodynamics, and coronary and renal circulation. Arterial stiffness modulates ventricular loading conditions and diastolic function, key components of HF with preserved ejection. Endothelial function and arterial stiffness may therefore serve as important physiological targets for new HF therapies and facilitate patient selection for improved application of existing agents.

Left ventricular systolic dysfunction associated with pulmonary hypertension riociguat trial (LEPHT): rationale and design

AIMS

Pulmonary hypertension (PH) due to systolic left ventricular dysfunction (PH-sLVD) frequently complicates heart failure (HF), and greatly worsens the prognosis of patients with sLVD, but as yet has no approved treatment. The LEPHT study aims to characterize the haemodynamic profile, safety, tolerability, and pharmacokinetic profile of riociguat (BAY 63-2521), an oral stimulator of soluble guanylate cyclase, in patients with PH-sLVD.

METHODS AND RESULTS

This 16-week, phase IIb, randomized, placebo-controlled, double-blind study enrols patients with PH-sLVD, defined as left ventricular ejection fraction (LVEF) ≤40% and mean pulmonary arterial pressure (PAP(mean)) ≥25 mmHg at rest. Patients using optimized HF medication will receive placebo or riociguat 0.5 mg, 1 mg, or up to 2 mg three times daily. The dose will be titrated for 8 weeks, based on systolic blood pressure and well-being, followed by 8 weeks of treatment at a stable dose. The primary efficacy variable is PAP(mean), while secondary efficacy endpoints include LVEF, exercise capacity, quality of life, and other haemodynamic and echocardiographic measurements. Safety and pharmacokinetics will also be assessed. After the 16-week study, patients will have the opportunity to be treated with riociguat in a long-term extension phase.

CONCLUSION

The LEPHT study will provide valuable information on the haemodynamic, echocardiographic, and preliminary clinical effects of riociguat in patients with PH-sLVD. Trial registration NCT01065454.

Statins in non-ischaemic cardiomyopathy: an update on our current clinical and pathophysiological understanding

Statins are a cornerstone in reducing cardiovascular events. Studies show that statins are beneficial even in patients with normal or low cholesterol levels, indicating pleiotropic mechanisms of therapeutic benefit apart from their antihyperlipidemic effect. Non-randomised, observational and retrospective studies suggest that statins are associated with better outcomes in patients with heart failure (HF) of both ischaemic and non-ischaemic aetiologies. While cholesterol reduction and plaque stabilisation likely play a role in reducing cardiovascular events in ischaemic HF patients, the mechanisms underlying the benefit in non-ischaemic HF patients is less clear. This review suggests the pleiotropic effects of statin therapy can beneficially alter the pathophysiological mechanisms underlying the clinical benefit observed in non-ischaemic HF patients.

Reduced regional myocardial perfusion reserve is associated with impaired contractile performance in idiopathic dilated cardiomyopathy

Background. In idiopathic dilated cardiomyopathy (IDC) an imbalance between myocardial oxygen consumption and supply has been postulated. Subclinical myocardial ischaemia may contribute to progressive deterioration of left ventricular function. The relation between regional myocardial perfusion reserve (MPR) and contractile performance was investigated.Methods. Patients with newly diagnosed IDC underwent positron emission tomography (PET) scanning using both (13)N-ammonia as a perfusion tracer (baseline and dypiridamole stress), and (18)F-fluorodeoxyglucose viability tracer and a dobutamine stress MRI. MPR (assessed by PET) as well as wall motion score (WMS, assessed by MRI) were evaluated in a 17-segment model.Results. Twenty-two patients were included (age 49+/-11 years; 15 males, LVEF 33+/-10%). With MRI, a total of 305 segments could be analysed. Wall motion abnormalities at rest were present in 127 (35.5%) segments and in 103 (29.9%) during dobutamine stress. Twenty-one segments deteriorated during stress and 43 improved. MPR was significantly higher in those segments that improved, compared with those that did not change or were impaired during stress (1.87+/-0.04 vs. 1.56+/- 0.07 p<0.01.)Conclusion. Signs of regional ischaemia were clearly present in IDC patients. Ischaemic regions displayed impaired contractility during stress. This suggests that impaired oxygen supply contributes to cardiac dysfunction in IDC. (Neth Heart J 2009;17:470-4.).

Coronary flow reserve in idiopathic dilated cardiomyopathy: relation with left ventricular wall stress, natriuretic peptides, and endothelial dysfunction

Studies have demonstrated impaired coronary blood flow reserve (CBFR) in idiopathic dilated cardiomyopathy (IDCM). It was the aim of this study to examine the potential underlying mechanisms for CBFR reduction in patients with IDCM by Doppler ultrasound techniques. Forty-eight clinically stable patients with heart failure caused by IDCM (New York Heart Association classes 1-3) were evaluated by echocardiographic and Doppler techniques with the assessments of CBFR and brachial artery flow-mediated dilation (FMD). CBFR was estimated as the hyperemic (dipyridamole: 0.84 mg/kg in 10 minutes, intravenously) to resting coronary diastolic peak velocities ratio. N-terminal pro-brain natriuretic peptide (Nt-pro-BNP) plasma levels were measured at the time of the index echocardiogram. Left ventricular (LV) ejection fraction was 30% +/- 8%, and wall motion score index was 2.0 +/- 0.25. The best correlation with CBFR was found with LV wall thickness-to-cavity radius (r = 0.77, P < .0001). A strong correlation of log-transformed Nt-pro-BNP levels was observed with CBFR (r = -0.64; P < .0001). No significant correlation was documented between CBFR and FMD. The stepwise regression model showed that LV wall thickness-to-cavity radius was the strongest independent predictor of CBFR followed by New York Heart Association class and log-transformed Nt-pro-BNP leading to a cumulative R value of 0.82 (P < .0001). The results of the study indicate that by measuring variables related to LV end-diastolic wall stress, such as LV wall thickness-to-cavity radius and plasma Nt-proBNP, it is possible to have information about CBFR in patients with heart failure secondary to IDCM.

Plasma lipoprotein-associated phospholipase A2 levels in heart failure: association with mortality in the community

OBJECTIVE

Lipoprotein-associated phospholipase A2 (Lp-PLA2) is a useful inflammatory marker of cardiovascular risk, yet little is known of its prognostic role in heart failure (HF). We evaluated the association of Lp-PLA2 with mortality in subjects with HF and assessed its incremental value for risk discrimination over established risk factors and biomarkers.

METHODS

Residents of Olmsted County, MN, diagnosed with HF between September 2003 and April 2007 (n=646, mean age 76 years, 51% women) were prospectively enrolled and followed-up. Plasma Lp-PLA2 levels were measured at baseline and evaluated along with known risk indicators.

RESULTS

Lp-PLA2 was positively associated with male gender and low-density lipoprotein cholesterol and inversely associated with statin use and diabetes. During follow-up (median 21 months), 213 deaths occurred. Elevated Lp-PLA2 was associated with an increased risk of mortality (hazard ratio (HR)=1.57; 95% confidence interval (CI): 1.03-2.37; P=0.035, per 1-unit increase in the log-transformed values). The relationship differed markedly by age (P(interaction)=0.003), with a strong association in patients under 80 years (covariate-adjusted HR=3.83; 95% CI: 1.93-7.61; P<0.001) and none in older ones (covariate-adjusted HR=0.82; 95% CI: 0.44-1.51; P=0.55). For the younger subjects, an improvement in the model's discriminatory power was obtained by adding Lp-PLA2 to established risk indicators and biomarkers (area under the receiver operating characteristic curve, 0.709-0.744, P(difference)=0.008).

CONCLUSION

In this community-based cohort of patients with HF, Lp-PLA2 was strongly and independently associated with mortality and contributed incrementally to risk discrimination in patients under 80 years of age.

Effects of levosimendan on coronary artery flow and cardiac performance in patients with advanced heart failure

BACKGROUND

Levosimendan has inotropic and vasodilatory effects. We investigated the effects of levosimendan on coronary flow and associated changes in neurohormonal activation and cardiac performance in patients with advanced heart failure.

METHODS

Forty-two patients with NYHA III-IV and a left ventricular ejection fraction (EF) 25+/-6%, were randomised to levosimendan 0.1 microg/kg/min (n=21) or placebo for 24 h. Before and 24 h after each treatment, we assessed: the maximal velocity (Vmax), time integral (VTI) and deceleration time (DT) of the diastolic coronary flow wave (CF) in LAD using transthoracic Doppler echocardiography, pulmonary artery systolic pressure by Doppler echocardiography, E/E' ratio using Doppler imaging of mitral inflow velocity, tissue Doppler imaging of the mitral annulus and B-type natriuretic peptide (BNP) levels.

RESULTS

By ANOVA, there was a greater increase in CF-Vmax (43+/-23 vs.25+/-8 cm/s), CF-DT (904+/-250 vs. 667+/-151 ms), and EF and a greater decrease in BNP, pulmonary artery systolic pressure and E/E? after levosimendan than after placebo (p<0.05). Compared to baseline, the percent changes in CF-VTI were related to the concomitant changes in EF, E/E?, and BNP after treatment with levosimendan (r=0.69, r=?0.51 and r=?0.80, p<0.05 respectively).

CONCLUSION

Treatment with levosimendan improves coronary flow and microcirculation in parallel with an improvement in cardiac performance and neurohormonal activation in patients with advanced heart failure.

Acute effect of esmolol intravenously on coronary microcirculation in patients with idiopathic dilated cardiomyopathy

Although coronary flow reserve (CFR) impairment was correlated with the prognosis of patients with idiopathic dilated cardiomyopathy (IDC) and microvascular ischemia was implicated in the progress of the disease, little is known about the effect of the established therapy with beta blockers on coronary microcirculation. The purpose of this study was to assess the effect of beta(1) blockade on coronary blood flow and CFR in patients with IDC. Fourteen patients with IDC and 10 control subjects underwent time-averaged peak coronary flow velocity (APCFV) measurements (centimeters per second) in the proximal left anterior descending coronary artery at baseline and at maximal hyperemia before and after beta(1) blockade with intravenous esmolol. CFR was defined as APCFV at maximal hyperemia/APCFV at baseline. Although there were no significant differences in APCFV at baseline between patients with IDC and controls, patients with IDC had significantly lower APCFV at maximal hyperemia than controls (54.2 +/- 12.0 vs 75.1 +/- 18.6, p <0.05) and decreased CFR (2.39 +/- 0.38 vs 3.50 +/- 0.54, respectively, p <0.05). After beta(1) blockade, a significant decrease in APCFV at baseline (19.5 +/- 3.7 vs 22.9 +/- 5.0, p <0.05) and enhancement of APCFV at maximal hyperemia (59.5 +/- 13.3 vs 54.2 +/- 12.0, p <0.05) were observed in patients with IDC, but not in control subjects, leading to significant improvement in CFR (3.06 +/- 0.40 vs 2.39 +/- 0.38, p <0.05). In conclusion, patients with IDC had alterations in coronary blood flow and decreased CFR that improved after beta(1) blockade. These alterations in microvascular function, which are partially reversed by beta blockade, may be 1 of the underlying mechanisms that contribute to the improved prognosis of patients with IDC under such therapy.

Drug Insight: statins for nonischemic heart failure—evidence and potential mechanisms

While 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors, also known as statins, have a well-established in role in the treatment and prevention of ischemic coronary artery disease, their utility in the setting of heart failure (HF) and left ventricular (LV) dysfunction remains under investigation. Although a reduction in LDL is the major effect of statin therapy, pleiotropic effects have been demonstrated, which could be responsible for the reduction in morbidity and mortality seen with statin use in patients with HF. Patients with both ischemic and nonischemic HF have been shown to have improved survival with statin therapy, and patients receiving statin therapy are less likely to develop HF. Studies have demonstrated that statins reduce inflammation, improve endothelial function, decrease thrombogenicity, and improve LV and autonomic function. In this Review, we present the literature supporting the pleiotropic effects of statin therapy in patients with HF or LV dysfunction, and discuss the mechanisms by which statins might elicit the improvements in morbidity and mortality seen in these patients.

Restoration of impaired endothelium-dependent coronary vasodilation in failing heart: role of eNOS phosphorylation and CGMP/cGK-I signaling

In congestive heart failure (CHF), coronary vascular relaxation is associated with endothelial dysfunction and nitric oxide (NO) deficiency. This study explored the reversibility of this process in hearts recovering from CHF and its related mechanisms. Dogs were chronically instrumented to measure cardiac function and coronary blood flow (CBF). Heart failure was induced by right ventricular pacing at 240 beats/min for 3-4 wk, and cardiac recovery (CR) was allowed by the termination of cardiac pacing for 3-4 wk after the development of CHF, in which left ventricular contractile function was restored by 80-90%. The endothelium-dependent CBF response to bradykinin and acetylcholine was depressed in CHF and fully restored in CR. Myocardial NOx (nitrate/nitrite), endothelial NO synthase (eNOS) mRNA expression, total protein, and phosphorylated eNOS decreased significantly in failing hearts. However, myocardial NOx recovered to 78% of control and phosphorylated eNOS was fully restored in CR, despite the fact that eNOS mRNA expression and protein levels remained lower than control. Furthermore, the endothelium-independent CBF response to nitroglycerin did not change in CHF; however, it increased by 75% in CR, in conjunction with a near threefold increase in the phosphorylation of vasodilation-stimulated phosphoprotein (VASP) at Ser(239) in recovering hearts. Thus the complete restoration of endothelium-dependent coronary vascular relaxation during cardiac recovery from CHF was mediated by 1) a restoration of phosphorylated eNOS for partial recovery of the NO production and 2) an increase in cGMP/cGMP-dependent protein kinase-I pathway signaling activity for the enhancement of coronary vascular smooth muscle relaxation in response to NO.

Variable response of conductance and resistance coronary arteries to endothelial stimulation in patients with heart failure due to nonischemic dilated cardiomyopathy

Attenuation of endothelial-dependent coronary vasodilation has been reported in idiopathic dilated cardiomyopathy and anatomically normal coronaries; however, data are insufficient for understanding the incidence and extent of this finding. The response of conductance and resistance coronary arteries to endothelial stimulation with acetylcholine was examined in 25 patients. Coronary blood flow had a variable response to acetylcholine and suggested coronary endothelial dysfunction in approximately half of the patients. Abnormal endothelial dysfunction involved the large conductance epicardial coronary arteries and the small resistance vessels. Abnormal endothelial response of coronary blood flow to acetylcholine could not be predicted by demographic and hemodynamic data.

CONCLUSIONS

Coronary artery endothelial function is heterogeneous in patients with idiopathic dilated cardiomyopathy. Endothelial dysfunction is present in approximately half of the cases and involves both resistance as well as conductance coronary blood vessels. Furthermore, coronary endothelial function cannot be predicted by demographic and hemo-dynamic parameters or left ventricular ejection fraction.

Coronary flow, VO2 peak and anaerobic threshold in patients with dilated cardiomyopathy

BACKGROUND

Coronary flow is influenced by several determinants and may change according to external stimuli. In patients with dilated cardiomyopathy (DC), adaptive mechanisms could induce alterations in coronary flow, possibly related to oxygen consumption.

METHODS

In 67 consecutive patients with DC (mean age 52.06+/-13.84, 52 male gender, left ventricle ejection fraction (LVEF) 29.49%+/-8.68) and normal coronary angiography findings, coronary flow in left anterior descending (LAD), right coronary artery (RC) and left circumflex (LCx) was reported as TIMI frame count (TFC). All patients underwent a cardiopulmonary test with VO2 peak and anaerobic threshold (AT) measurement, New York Heart Association (NYHA) class stratification, two-dimensional echocardiographic evaluation including LVEF and left ventricle end-diastolic diameter (LVEDD) assessment. All patients were receiving optimal medical treatment.

RESULTS

In a multivariate analysis, a statistically significant correlation was found between VO2 peak and TFC (B 7.61, p<0.001, R2 0.61 for LAD; B 3.42, p<0.001, R2 0.33 for RC); an inverse correlation was found between AT and TFC (B -9.77, p<0.001, R2 0.61 for LAD; B -4.26, p<0.001, R2 0.33 for RC).

CONCLUSIONS

Coronary flow is related to VO2 peak and AT in patients with DC, suggesting a "compensatory" mechanism.

Adjunctive therapy with low-molecular-weight heparin in patients with chronic heart failure secondary to dilated cardiomyopathy: one-year follow-up results of the randomized trial

BACKGROUND

Defective endothelial function has been shown in dilated cardiomyopathy. Therefore, improvement in endothelial function after low-molecular-weight heparin (LMWH) therapy may be clinically beneficial. Consequently, the effect of adjunct enoxaparin, a LMWH, on standard treatment of dilated cardiomyopathy was investigated.

METHODS

This was a randomized, standard treatment-controlled, 2-center pilot trial of 102 patients (52 receiving adjunctive therapy with enoxaparin at a dosage of 1.5 mg/kg daily for 3 months and 50 receiving standard therapy with angiotensin-converting enzyme inhibitors, beta-blockers, and diuretics alone) with stable chronic heart failure secondary to dilated cardiomyopathy (New York Heart Association [NYHA] class II and III; left ventricular [LV] ejection fraction, < or = 40%). All patients underwent coronary angiography and endomyocardial biopsy and were clinically stable for at least 6 months before enrollment. The combined primary end point included mortality, urgent heart transplantation, and readmission to hospital due to heart failure progression. The secondary end point was to determine the severity of heart failure (serum level of N-terminal brain natriuretic peptide), cardiac function (LV ejection fraction by radionuclide ventriculography), LV diameters by echocardiography, exercise capacity (changes in NYHA class, changes in peak oxygen consumption), and changes in quality of life (Minnesota Living with Heart Failure questionnaire). The clinical outcome was assessed after 6 and 12 months of therapy.

RESULTS

Baseline characteristics were comparable in both groups. Five patients dropped out during 12 months of the study. Twelve patients achieved primary end point (8 in the control group and 4 in the LMWH group). The free survival rate was 94% for the LMWH group and 90% for the controls (not statistically significant). After the 12-month period, in the LMWH group, N-terminal brain natriuretic peptide level and LV diameters decreased significantly (P < .001 and P = .006, respectively), whereas LV systolic function increased (P < .001). Changes in exercise capacity and subjective improvement did not differentiate the groups (nonsignificant). Adverse reactions to the enoxaparin therapy were minor and transient.

CONCLUSIONS

In patients with chronic heart failure due to dilated cardiomyopathy, adjunct long-term enoxaparin therapy may offer additional clinical benefit without deleterious effects on major cardiac events.

ETBreceptor dependent alteration in aortic responses to ET-1 in the cardiomyopathic hamsterThis paper is one of a selection of papers published in this Special issue, entitled Second Messengers and Phosphoproteins—12th International Conference

The aim of this study was to verify whether an alteration in the aortic endothelin-1 (ET-1) response takes place in UM-X7.1 cardiomyopathic hamsters. Our results showed that ET-1 (10−12– 10−5 mol/L) induces dose-dependent sustained increases in tension in the intact and endothelium denuded aortas from both normal and cardiomyopathic hamsters. The EC50values of ET-1 of both intact and endothelium denuded aortas of normal hamsters were similar (2.2 × 10−9 mol/L and 1.8 × 10−9 mol/L, respectively). However, in cardiomyopathic hamsters, the EC50of ET-1 in intact aortas was higher (1.5 × 10−8 mol/L) than that of the endothelium denuded preparations (2.7 × 10−9 mol/L). The EC50of ET-1 in normal and cardiomyopathic hamster denuded aortas were similar. However, the EC50of ET-1 in intact aortas of cardiomyopathic hamster was higher (1.5 × 10−8 mol/L) than that of normal hamsters (2.2 × 10−9 mol/L). Pre-treatment with the ETAreceptor antagonist ABT-627 (10−5 mol/L) of intact and endothelium denuded aortas from both normal and cardiomyopathic hamsters significantly prevented ET-1 (10−7 mol/L) from inducing an increase in tension. Pre-treatment with the ETBreceptor antagonist A-192621 (10−5 mol/L) had no effect on the ET-1-induced increase in tension in endothelium denuded aortas of both normal and cardiomyopathic hamsters, as well as in intact preparations of normal animals. However, blockade of the ETBreceptors in intact aortas of cardiomyopathic hamsters significantly (p < 0.001) potentiated the ET-1-induced increase in tension. In summary, an attenuation of the contraction response to ET-1 was found in UM-X7.1 cardiomyopathic hamsters when compared with normal age-matched hamsters. This alteration of the ET-1 effect in the aortas of cardiomyopathic hamsters seems to be dependent on the presence of the endothelium and could be due, in part, to an increase in the contribution of endothelial ETBreceptors to relaxation, which in turn acts as a physiological depressor of ET-1 vasoconstriction. Our results suggest that an increase in the endothelium ETBreceptor density may play a role in the development of hypotension in UM-X7.1 cardiomyopathic hamsters.

The relationship between shear stress and flow-mediated dilatation: implications for the assessment of endothelial function

Endothelium-dependent flow-mediated dilatation (FMD) describes the vasodilatory response of a vessel to elevations in blood flow-associated shear stress. Nitric oxide (NO), one of many vasoactive substances released by the endothelium in response to shear stress, is of particular interest to researchers as it is an antiatherogenic molecule, and a reduction in its bioavailability may play a role in the pathogenesis of vascular disease. The goal of many human studies is to create a shear stress stimulus that produces an NO-dependent response in order to use the FMD measurements as an assay of NO bioavailability. The most common non-invasive technique is the 'reactive hyperaemia test' which produces a large, transient shear stress profile and a corresponding FMD. Importantly, not all FMD is NO mediated and the stimulus creation technique is a critical determinant of NO dependence. The purpose of this review is to (1) explain that the mechanisms of FMD depend on the nature of the shear stress stimulus (stimulus response specificity), (2) provide an update to the current guidelines for FMD assessment, and (3) summarize the issues that surround the clinical utility of measuring both NO- and non-NO-mediated FMD. Future research should include (1) the identification and partitioning of mechanisms responsible for FMD in response to various shear stress profiles, (2) investigation of stimulus response specificity in coronary arteries, and (3) investigation of non-NO FMD mechanisms and their connection to the development of vascular disease and occurrence of cardiovascular events.

Coronary Blood Flow Responses are Impaired Independent of NO and Endothelial Function in Conscious Dogs with Dilated Cardiomyopathy

BACKGROUND

Dilated cardiomyopathy (DCM) is characterized by nitric oxide (NO) deficiency and endothelial dysfunction. Whether endothelium-independent vasodilation is preserved, particularly in the coronary circulation, remains controversial.

METHODS AND RESULTS

We studied systemic and coronary flow responses to the endothelium-dependent agonist, acetylcholine, the cGMP-dependent NO-donor, nitroglycerin, the predominantly endothelium-independent agonist, adenosine, the beta-adrenergic cAMP-dependent agonist, isoproterenol, and the calcium channel antagonist, nicardipine, in conscious dogs with pacing-induced DCM. Systemic blood flow response was impaired to acetylcholine but preserved to other vasodilators in DCM. In contrast, coronary blood flow response was significantly ( P < .05) depressed to all agonists. (Peak coronary blood flow response, control versus DCM: acetylcholine: 221 +/- 14% versus 156 +/- 11%; nitroglycerin: 220 +/- 17% versus 138 +/- 9%; adenosine: 635 +/- 65% versus 376 +/- 56%; nicardipine: 338 +/- 59% versus 115 +/- 23%; isoproterenol: 219 +/- 18% versus 86 +/- 20%). The attenuation was independent of systemic hemodynamic differences.

CONCLUSION

In contrast to systemic responses, coronary blood flow responses in DCM are impaired dependent or independent of NO or second messenger mechanisms, implying either distal signaling defects or structural abnormalities in the coronary vasculature.

Systemic endothelial dysfunction as an early predictor of adverse outcome in heart failure

OBJECTIVE

Endothelial dysfunction is an early event in the natural progression of heart failure. Increased oxidative stress has been linked to impaired endothelial function and both may play a prognostic role.

METHODS AND RESULTS

Endothelium-dependent and endothelium-independent vasodilatation were determined in 289 patients with mild left ventricular dysfunction by measuring forearm blood flow responses to acetylcholine and sodium nitroprusside using venous occlusion plethysmography. Vascular effects of the coadministration of the antioxidant vitamin C at pharmacological doses (24 mg/min) were assessed. Occurrence of death, heart transplantation, and readmission with worsening heart failure were recorded as clinical outcome parameters during a follow-up period of 4.8 years. Patients experiencing adverse events (n=79) had lower vasodilator responses to acetylcholine (P<0.001) and to sodium nitroprusside (P=0.03) compared with patients without events. However, beneficial effects of vitamin C did not differ between both groups. Cox proportional hazards model demonstrated that age (P=0.001), renal function (P=0.001), and blunted acetylcholine-induced vasodilatation (P=0.007) remained independent predictors of adverse outcome.

CONCLUSIONS

Impaired peripheral endothelial function independently predicts long-term adverse outcome in patients with early-stage heart failure. The findings suggest that assessment of peripheral endothelial function may represent an additional mean for risk stratification and therapy management in these patients.

Variations of Endothelium-Dependent Vasoresponses in Congestive Heart Failure

Endothelium-dependent vasodilation decreases in patients with congestive heart failure (CHF). Whether this decreased vasodilation occurs simultaneously in different vascular beds has not been elucidated. We studied the vasomotor reactivity in both coronary and peripheral resistance vessels in a rat CHF model produced by ligating the left coronary artery. Variations in vessel diameter in response to vasoactive drug administration were measured using an in vitro system of coronary resistance vessels from cardiac muscle and peripheral resistance vessels from cremaster muscle. Vascular responses to acetylcholine were impaired in the early stage of CHF (at 2 weeks), whereas the reaction to bradykinin was preserved. NG-monomethyl-L-arginine (L-NMMA) inhibited the responses of acetylcholine; however, L-NMMA only partially inhibited the responses to bradykinin. Vascular reactivity to A23187 was preserved in the early stage and was impaired in the late stage of CHF (at 8 weeks). These reactions were inhibited by L-NMMA. The response to sodium nitroprusside remained constant in both stages of CHF. The responses were similar in the coronary resistance and peripheral resistance vessels. This suggests that acetylcholine transmission is impaired in the early stages of CHF but that with CHF of longer duration there is progressive impairment of nitric oxide production and release in both coronary and peripheral resistance vessels.

Regional coronary flow and contractile reserve in patients with idiopathic dilated cardiomyopathy

OBJECTIVES

The purpose of this study was to assess regional coronary flow and contractile reserve in patients with idiopathic dilated cardiomyopathy (IDCM).

BACKGROUND

Although IDCM has been associated with alterations in coronary blood flow and contractile reserve, little is known about their regional distribution and correlation.

METHODS

Fourteen patients with IDCM and 11 control subjects underwent coronary flow velocity (APV) measurements in the left anterior descending (LAD), left circumflex (LCx), and right coronary (RCA) arteries at baseline (b) and at maximal hyperemia (h). Coronary flow reserve (CFR) was defined as h-APV/b-APV. Wall thickening was assessed in 16 segments (7 assigned to LAD, 5 to LCx, and 4 to RCA) both at rest and under peak stress during low-dose dobutamine echocardiography. Regional contractile reserve was defined as the percentage difference in wall motion score index between rest and stress in each vascular territory.

RESULTS

Although there were no significant differences in b-APV, patients with IDCM had significantly lower h-APV than controls in all three vascular territories and reduced CFR (LAD: 2.79 +/- 0.43 vs. 3.48 +/- 0.51, p < 0.05; LCx: 2.71 +/- 0.39 vs. 3.36 +/- 0.65, p < 0.05; and RCA: 3.43 +/- 0.55 vs. 4.02 +/- 0.73, p < 0.05). There was also a significant correlation between CFR and the corresponding contractile reserve in the vascular territory of the LAD (r = 0.75, p = 0.002) and the LCx (r = 0.64, p = 0.014).

CONCLUSIONS

Patients with IDCM have alterations in regional coronary flow and reduced CFR. Furthermore, the correlation between regional CFR and the corresponding contractile reserve indicates that microvascular dysfunction may have a pathophysiologic role in the evolution of the disease.

Coxsackievirus B3 infection compromises endothelial-dependent vasodilation of coronary resistance arteries

The mechanisms of coronary artery dysfunction in coxsackievirus B3 (CVB3)-mediated viral myocarditis are poorly understood. We used pressure myography of mouse septal coronary arteries to determine the early and late effects of CVB3 infection on vascular function. Male CD-1 mice (age 6-7 weeks) were infected with CVB3 (1.75 x 10(10) pfu, i.p.). Control mice were injected with PBS. Mice were killed at 3, 7, and 42 days post infection, and the ventricular septal artery was dissected and mounted on a pressure myograph. Pressure-induced myogenic tone was similar in CVB3-infected and sham-infected mice at 3 and 7 days post infection. However, at 42 days post infection constriction of septal arteries to pressures equal to or less than 60 mm Hg was enhanced in CVB3-infected mice compared with sham controls. Agonist-induced vasodilation, as assessed by response to acetylcholine (1 nM-3 microM), was unaltered at early time points (days 3 and 7) in CVB3-infected mice. At later time points (day 42), there was a significant decrease in ACh-induced vasodilation in CVB3-infected mice. Bosentan, an ET-1 (ETA and ETB) receptor antagonist, did not completely ameliorate the reduced ACh-induced vasodilation in 42-day infected mice, indicating that ET-1 does not contribute to vascular dysfunction. Smooth muscle function, as measured by constriction to KCl or dilation to sodium nitroprusside, was unchanged in infected mice at early and late time points. Immunohistochemistry and ET-1 immunoassay were then performed to assess ET-1 levels in CVB3- and sham-infected hearts. There were no differences in ET-1 protein localization or levels at 42 days post infection in sham- and CVB3-infected animals. Finally, in situ hybridization and TUNEL staining were performed to assess viral localization and cell death in CVB3-infected hearts. There was no detectable CVB3 or TUNEL positivity in the endothelium of coronary arteries. Therefore, late impairment of endothelial-dependent vasorelaxation of coronary resistance vessels in CVB3-induced myocarditis does not appear to involve altered ET-1 expression but may be secondary to decreased stimulated NO secretion by the endothelium.

Heart failure with silent coronary artery spasm exhibiting microscopic focal myocardial necrosis and amyloid-deposition

We report a 67-year-old Japanese man who presented with worsening heart failure with asymptomatically transient ischemic ST-segment depression. Left ventriculography showed diffuse hypokinesis; asymptomatic coronary artery spasm was evoked by the acetylcholine provocation test. Endomyocardial biopsy exhibited hypertrophic cardiomyocytes and scattered microscopic focal myocardial necrosis with amyloid-deposition. Transient ST-segment depression improved after treatment with a calcium antagonist, but cardiac contraction was still impaired. We hypothesize that asymptomatic coronary spasm may cause irreversible cardiac damage and heart failure with amyloid-deposition; the presence or absence of coronary spasm in heart failure patients should be clarified in order to determine therapeutic strategy.