Release of leukotriene B4, transforming growth factor-beta1 and microparticles in relation to aortic valve calcification.

BACKGROUND AND AIM OF THE STUDY: Aortic stenosis, the most frequent valvulopathy in the Western world, is characterized by an important extracellular matrix (ECM) remodeling and a process of calcification in the aortic valves. One physiopathological assumption is that transforming growth factor-beta1 (TGF-beta1) acts through ECM remodeling and plays a role in calcification, implicating also microparticles (MPs). Another recent notion is the active involvement of inflammatory mediators in the calcification process of aortic stenosis. METHODS: A total of 105 aortic valves was collected from patients suffering from calcified aortic stenosis with either tricuspid valve (AS) or bicuspid aortic valve (BAV), rheumatic aortic stenosis (RA), endocarditis, or aortic regurgitation (AR). Each valve was incubated for 24 h in culture medium and the supernatants (conditioned media) were used to measure the concentrations of leukotriene B4 (LTB4) and TGF-beta1 and to quantify the number of MPs released. Valvular calcification was evaluated using biphotonic absorptiometry. RESULTS: LTB4 concentrations were significantly higher in media conditioned by AS valves compared to those conditioned by RA and endocarditis valves. In addition, LTB4 concentrations correlated significantly with the calcium content of the aortic valves. In contrast, the concentrations of TGF-beta1 and MPs in the conditioned media did not differ significantly between the various groups of valves, and there was no significant correlation between calcification and either TGF-beta1 or the number of MPs released from the aortic valves. CONCLUSION: Taken together, these results indicate that inflammatory signaling through LTB4 may be more closely linked to calcification and aortic stenosis than signaling through TGF-beta1 and MPs.

Severe aortic stenosis management in heart valve centres compared with primary/secondary care centres.

OBJECTIVE: Current guidelines recommend use of heart valve centres (HVCs) to deliver optimal quality of care for patients with valve disease but there is no evidence to support this. The hypothesis of this study is that patient care with severe aortic stenosis (AS) will differ in HVCs compared with satellite centres. We aimed to compare the treatment of patients with AS at HVCs (tertiary care hospitals with full access to AS interventions) to satellites (hospitals without such access). METHODS: IMPULSE enhanced is a European, observational, prospective registry enrolling consecutive patients with newly diagnosed severe AS at four HVCs and 10 satellites. Clinical characteristics, interventions performed and outcomes up to 1 year by site-type were examined. RESULTS: Among 790 patients, 594 were recruited in HVCs and 196 in satellites. At baseline, patients in HVCs had more severe valve disease (higher peak aortic velocity (4.3 vs 4.1 m/s; p=0.008)) and greater comorbidity (coronary artery disease (CAD) (44% vs 27%; p<0.001) prior myocardial infarction (MI) (11% vs 5.1%; p=0.011) and chronic pulmonary disease (17% vs 8.9%; p=0.007)) than those presenting in satellites. An aortic valve replacement was performed more often by month 3 in HVCs than satellites in the overall population (52.6% of vs 31.3%; p<0.001) and in symptomatic patients (66.7% vs 43.2%, p<0.001). One-year survival rate was higher for patients in HVCs than satellites (HR2.19; 95% CI 1.28 to 3.73 total population and 2.89 (95%CI 1.64 to 5.11) for symptomatic patients. CONCLUSIONS: Our data support the implementation of referral pathways that direct patients to HVCs performing both surgery and transcatheter interventions. TRIAL REGISTRATION NUMBER: NCT03112629.

Plasmin induces apoptosis of aortic valvular myofibroblasts.

Previous studies have described remodelling of the extracellular substratum by matrix metalloproteinases (MMPs) in aortic valves. However, involvement of the fibrinolytic system has not yet been analysed. We hypothesized that plasminogen and plasminogen activator(s) are present in aortic valves and that plasminogen activation could induce the degradation of adhesive proteins and apoptosis of the valvular myofibroblasts. We employed ELISA, western blotting, fibrin-agar zymography, and immunochemistry to detect components of the plasminogen activation system, in samples of aortic valves and valvular myofibroblasts in primary culture. Using myofibroblast cultures, real-time measurement of plasminogen activation was performed in the absence and presence of inhibitors (amiloride, epsilon-aminocaproic acid, and an MMP inhibitor); the degradation of fibronectin was visualized on western blots; and the apoptotic process was assessed by detection of phosphatidylserine exposure (binding of FITC-annexin V) and DNA fragmentation (TUNEL and ELISA). We demonstrate that a time- and plasminogen concentration-dependent generation of plasmin occurs on the surface of cultured valvular myofibroblasts expressing both u-PA and t-PA. Only u-PA appears to activate plasminogen as t-PA is essentially found in complex with PAI-1. Plasmin-dependent degradation of pericellular proteins, such as fibronectin, leads to cell detachment and apoptosis. In conclusion, various proteins of the fibrinolytic system are synthesized in vitro by cultured myofibroblasts from aortic valves, leading to plasmin-dependent cell detachment-induced apoptosis, a biological process named anoikis. The presence of plasminogen in aortic valves suggests that this process may be operating in vivo and may participate in valvular tissue remodelling, as also suggested by the finding of apoptotic cells in valvular tissue. This is the first demonstration of the presence and potential role of enzymes of the fibrinolytic system in aortic valves.

High-cholesterol + vitamin D2 regimen: a questionable in-vivo experimental model of aortic valve stenosis.

BACKGROUND AND AIM OF THE STUDY: Recent data have shown that aortic valve stenosis (AS) is an active and highly regulated process which shares similarities with atherosclerosis. However, AS cannot be considered as a purely atherosclerotic phenomenon, and a hypercholesterolemic rabbit model might not be fully representative of human AS pathophysiology. METHODS: Twenty-eight New Zealand White rabbits were assigned to three groups: group 1 (no dietary supplement for three months); group 2 (0.3% cholesterol-enriched-diet + 50,000 IU/day vitamin D2 for six months); and group 3 (1% cholesterol-enriched-diet + vitamin D2 for three months). The peak aortic gradient and permeability index (outflow tract/aortic velocity-time-integral) were assessed, as well as calcium staining within the aortic valve and ascending aorta. RESULTS: AS hemodynamic severity was not different among the groups. The peak gradient was 4 +/- 2 mmHg at baseline, 4 +/- 2 mmHg at three months in controls, 4 +/- 1 mmHg at three months and 6 +/-3 mmHg at six months in group 2, and 4 +/- 1 mmHg at three months in group 3 (p = NS). The permeability index was 64 +/- 7 at baseline, 60 +/- 12 at three months in controls, 63 +/- 14 at three months and 58 +/- 12 at six months in group 2, and 60 +/- 5 at three months in group 3 (p = NS). The aortic valve of cholesterol-enriched-diet rabbits was thickened but not calcified, whereas the ascending aorta was both thickened and calcified. CONCLUSION: When using a hypercholesterolemic rabbit model plus vitamin D2, no adverse hemodynamic effect or aortic valve calcification was observed, despite a high-level and prolonged cholesterol-regimen supplementation. These results raise questions with regard to the extrapolation of this animal model to humans.

Caseload management and outcome of patients with aortic stenosis in primary/secondary versus tertiary care settings-design of the IMPULSE enhanced registry.

Background: Severe aortic stenosis (AS) is one of the most common and most serious valve diseases. Without timely intervention with surgical aortic valve replacement or transcatheter aortic valve replacement, patients have an estimated survival of 2-3 years. Guidelines for the treatment of AS have been developed, but studies suggest that as many as 42% of patients with AS are not treated according to these recommendations.The aims of this registry are to delineate the caseload of patients with AS, outline the management of these patients and determine appropriateness of treatments in participating centres with and without onsite access to surgery and percutaneous treatments. Methods/design: The IMPULSE enhanced registry is an international, multicentre, prospective, observational cohort registry conducted at four central full access centres (tertiary care hospitals) and at least two satellite centres per hub (primary/secondary care hospitals). An estimated 800 patients will be enrolled in the registry and patient follow-up will last for 12 months. Discussion: In addition to the primary aims determining the caseload management and outcome of patients with AS in primary, secondary and tertiary care settings, the registry will also determine a time course for the transition from asymptomatic to symptomatic status and the diagnostic steps, treatment decisions and the identification of decision-makers in tertiary versus primary/secondary care hospitals. The last patient will be enrolled in the registry in 2018 and results of the registry are anticipated in 2019. Registration number: NCT03112629.

A pneumococcal purulent pericarditis revealing a pneumonia and complicated by an acute cardiac tamponade.

Purulent pericarditis secondary to pneumococcal pneumonia is a rare entity, and often underestimated despite being associated with a high mortality rate. We report a case of a man who developed a cardiac tamponade related to a previously unknown pneumococcal pneumonia. In conclusion, we emphasize the need of repeated clinical and echocardiographic exams.

Preoperative use and safety of coronary angiography for acute aortic valve infective endocarditis.

BACKGROUND: Preoperative coronary angiography (CA) is recommended in patients with acute aortic valve infective endocarditis (AV-IE) and high cardiovascular risk profile but the level of evidence is low and its potential interest may be counterbalanced by the risk of dislodgement of vegetations and contrast-induced nephropathy. OBJECTIVE: To review the use, indications and complication of preoperative CA in patients with AV-IE. Design Retrospective study. PATIENTS: Consecutive series of 83 patients operated on for AV-IE between January 2002 and March 2007. RESULTS: CA was performed in 36 (43%) patients, all but one as a preoperative test. Significant (>or=70%) lesions were observed in 10 patients and six underwent an associated coronary artery bypass graft. 47 patients were operated on without preoperative CA because of young age in 16 or recent CA in 13. Despite being theoretically indicated in all but one of the 18 remaining patients, CA was not performed because surgery as judged too urgent (eight patients) or valvular lesions were estimated as too important (10 patients). While the 35 patients with preoperative CA tended to be healthier (longer time to surgery and lower rate of urgent surgery), anatomical lesions were not different (rate of severe regurgitation, periannular complications and vegetation size, all p>0.20). No embolic event occurred after CA and preoperative CA was not associated with increased in-hospital mortality (p=0.80) or worsening renal function (p=0.93). CONCLUSION: Preoperative CA can be performed at low risk in selected patients with AV-IE and should be considered before surgery in patients with cardiovascular risk factors. Our results support current guidelines.