Stephan Wiedemann

The iron-regulatory peptide hepcidin is upregulated in the ischemic and in the remote myocardium after myocardial infarction

Recent evidence suggests that iron metabolism contributes to the ischemic damage after myocardial infarction. Hepcidin, a recently discovered peptide hormone, regulates iron uptake and metabolism, protecting the body from iron overload. In this study we analyzed the regulation of hepcidin in the heart and blood of rats after myocardial infarction. To induce a myocardial infarction in the rats, left anterior descending coronary artery ligation was performed. After 1-24h, biopsies from the ischemic and the non-ischemic myocardium were taken. In these biopsies, the mRNA levels and the protein expression of hepcidin were analyzed by quantitative RT-PCR and immunoblot analysis, respectively. In parallel, the serum levels of prohepcidin were measured by ELISA. Six hours after myocardial infarction, the hepcidin mRNA expression was temporally upregulated in the ischemic and in the non-ischemic myocardium. The upregulation was specific for hepcidin, since other iron-related genes (hemojuvelin, IREG-1) remained unchanged. Furthermore, the alteration of the hepcidin protein expression in the ischemic area was connected to the level of hepcidin in the serum of the infarcted rats, where hepcidin also raised up. Angiotensin receptor blockade with candesartan did not influence the mRNA regulation of hepcidin. Together, these data show a particular upregulation of the iron-regulatory peptide hepcidin in the ischemic and the non-ischemic myocardium after myocardial infarction. It is speculated that upregulation of hepcidin may reduce iron toxicity and thus infarct size expansion in an infarcted heart.

Apoptosis at a distance: remote activation of caspase-3 occurs early after myocardial infarction.

AbstractObjective: After an acute myocardial infarction, the viable myocardium remote from the infarct zone is subjected to ventricular remodeling. Besides hypertrophy, processes of apoptosis may contribute to these remodeling processes. Reports on apoptosis in this area have been doubted because they were mainly based on in-situ nick-end DNA labeling (TUNEL) measurements, with questionable specifity. Moreover, the time course of initiation of these processes has not been characterized. Therefore the goals of this study were to (1) reliably determine if in the remote area of the infarcted heart apoptosis may be initiated using highly specific biochemical markers and (2) evaluate the time course of such an activation. Methods: A well-defined model, regional myocardial infarction induced by ligation of the left anterior coronary artery in rats in vivo, was used. Heart and lung wet weights, the left ventricular end-diastolic pressure (LVEDP), and the serum level of the atrial natriuretic propeptide (proANP) were determined from 1 day up to 4 weeks as indicators of developing heart failure. In transmural biopsies from the non-ischemic left ventricular wall of the infarcted heart, the activation of caspase-3, the bcl-2/bax ratio (Western blot analysis), and the DNA laddering (LM-PCR) were determined. Results: Although heart- and lung weights did not increase before 1 week after infarction, proANP levels were elevated already 1 day after myocardial infarction suggesting early sub-clinical heart failure. The activity of caspase-3 increased significantly to 160± 20% compared to sham operated controls as early as 1 day after ligation and remained elevated over the entire time course. In parallel, the bcl-2/bax ratio shifted toward the pro-apoptotic bax. Moreover, these clear and specific biochemical indicators of apoptosis in the remote area of the infarcted heart were paralleled by the fragmentation of genomic DNA. Conclusion: These data demonstrate that apoptotic markers are activated in the surviving zone of the heart remote from the infarct area as early as 1 day after myocardial infarction with persistence for up to 4 weeks. This activation coincides with early markers of heart failure. The exact regulation of this apoptotic process remains to be elucidated.

Association of platelet activation markers with recurrence of atrial fibrillation after pulmonary vein isolation

Abstract Atrial fibrillation (AF) is known to cause platelet activation. AF and its degree of thrombogenesis could be associated with monocyte-platelet aggregates (MPAs). We investigated on whether the content of MPAs or other platelet activation markers is associated with the recurrence of AF after pulmonary vein isolation (PVI). A total of 73 patients with symptomatic AF underwent PVI. After 6 months, all patients were evaluated for episodes of AF recurrence. At the same time, flow-cytometric quantification analyses were performed to determine the content of MPAs. Further platelet activation parameters were detected by using either cytometric bead arrays or quantitative immunological determination. Patients with recurrent AF (n = 20) compared to individuals without AF relapse (n = 53) were associated with an increased content of MPAs (43 ± 3% vs. 33 ± 2%, p = 0.004), as well as an increased CD41 expression on monocytes (191 ± 20 vs. 113 ± 6, p = 0.001). The level of the soluble platelet activation markers such as D-dimer, sCD40L, and sP-selectin did not differ between these groups. The content of MPAs correlated weakly with the level of sCD40L (r = 0.26, p = 0.03), but not with sP-selectin and D-dimer, whereas sP-selectin and sCD40L correlated with each other (r = 0.38, p = 0.001). Only the cellular marker of platelet activation, the content of MPAs, was increased in patients with recurrent AF after PVI. In contrast, soluble markers remained unaltered. These data indicate a distinct mechanism and level of platelet activation in AF. The clinical relevance of MPAs in identifying AF recurrence or in guiding the therapy with anticoagulants remains to be elucidated.

Reduction of atrial fibrillation burden by pulmonary vein isolation leads to a decrease of CD11b expression on inflammatory cells

Aims It is hypothesized that inflammation could promote structural and electrical remodelling processes in atrial fibrillation (AF). Atrial infiltration of monocytes and granulocytes has been shown to be dependent on CD11b expression. The aim of this study was to investigate whether treatment of AF by pulmonary vein isolation (PVI) may lead to reduced inflammation, as indicated by a decrease of CD11b expression on monocytes and granulocytes. Methods and results Flow-cytometric quantification analysis and determination of systemic inflammatory markers of peripheral blood were performed in 75 patients undergoing PVI 1 day before and 6 months after PVI. The extent of activation of monocytes and granulocytes was measured by quantifying the cell adhesion molecule CD11b. The mean expression of CD11b on monocytes (20.9 ± 2.5 vs. 10.2 ± 1.4; P < 0.001) and granulocytes (13.9 ± 1.6 vs. 6.8 ± 0.5; P < 0.001), as well as the relative count of CD11b-positive monocytes (P < 0.05) and CD11b-positive granulocytes (P < 0.01) were significantly reduced when comparing the identical patients before and 6 months after PVI. Systemic inflammatory parameters showed only a declining tendency after 6 months. Patients with unsuccessful PVI and ongoing AF on the day of follow-up showed no decrease in CD11b expression. Conclusions A significant reduction of CD11b expression on monocytes and granulocytes, as a sign of reduced cellular inflammation, was achieved by treatment of AF using PVI. These data strongly support that AF is not only a consequence of but also a cause for inflammatory processes, which, in turn, may contribute to atrial remodelling.

Three-dimensional transoesophageal echocardiography is crucial for valid assessment of mitral valve leaflet morphology in severe mitral regurgitation prior to interventional repair

Abstract Background: Interventional mitral valve (MV) repair of severe symptomatic mitral regurgitation (MR) is a therapeutic option in high-risk surgical or inoperable patients. Assessment of the MV remains a crucial part of pre-interventional screening. Three-dimensional transoesophageal echocardiography (3D-TOE) may compensate for well-known pitfalls that occur in 2D-TOE. Purpose: We investigated whether the functional length of the central segments of the posterior and anterior MV leaflets (PML-P2 and AML-A2) is more reliably determined by 3D-TOE full volume datasets (3D-MPR) or orthogonal biplane-imaging (Xplane) when compared to 2D-TOE. Methods and results: Between February 2014 and August 2015, 265 consecutive patients with moderate to severe symptomatic MR were screened. Seventy patients were judged suitable for interventional MV repair by the in-house Heart-Team. Eventually, 59 patients remained for data analysis. Inter-observer variability was lowest in 3D-MPR followed by Xplane (r = 0.92 and 0.90, p < .001 for both) and highest in Mplane (r = 0.82, p < .001). Mean functional PML-P2 lengths were similar in Xplane (12.6 ± 1.7 mm) and 3D-MPR (12.1 ± 2.0 mm), however, significantly different in 2D-TOE (10.0 ± 2.1 mm, p < .001). 2D-TOE underestimated PML-P2 length with a bias of –2.5 mm compared to Xplane and –1.95 mm compared to 3D-MPR. In contrast, functional AML-A2 length was determined similar across all methods. Conclusions: Our results demonstrate the superiority of 3D-TOE over 2D-TOE for accurate MV assessment in MR, especially for the determination of the functional PML length. Erroneous MV leaflet assessment may result in inadequate therapy restriction if the MV is deemed not suitable for interventional repair.

Comparison of diverse platelet activation markers as indicators for left atrial thrombus in atrial fibrillation

Abstract Atrial fibrillation (AF) is well known for being a major risk factor of thromboembolic stroke. We could recently demonstrate an association of monocyte–platelet aggregates (MPAs) with the degree of thrombogenicity in patients with AF. This study investigated platelet activation markers, as potential biomarkers for the presence of left atrial (LA) thrombus in patients with AF. One hundred and eight patients with symptomatic AF underwent transesophageal echocardiography (TEE) before scheduled cardioversion or pulmonary vein isolation. In order to determine the content of MPAs by flow-cytometric quantification analyses, blood was drawn on the day of TEE. The soluble CD40 Ligand (sCD40L) and soluble P-selectin (sP-selectin) were obtained by Cytometric Bead Arrays (CBA). D-dimer levels were detected by quantitative immunological determination of fibrin degradation products. Clinical, laboratory, and echocardiographic standard parameters were obtained from all patients, including the determination of the flow in the left atrial appendage (LAA). Patients with detected LA thrombus (n = 28) compared with patients without thrombus (n = 80) showed an increased number of common risk factors, such as age, diabetes, heart failure, and coronary artery disease (CAD). The presence of LA thrombus was associated with significantly increased levels of MPAs (147 ± 12 vs. 304 ± 29 per µl; p < 0.00), sCD40L (106.3 ± 31.0 vs. 33.5 ± 2.1 pg/ml, p = 0.027), and D-dimer (0.13 ± 0.02 vs. 0.69 ± 0.21 mg FEU/l, p = 0.015). In contrast, sP-selectin showed no association with LA thrombus. A multivariate regression analysis showed that MPAs, sCD40L as well as D-dimers were independent indicators for the existence of LA thrombus. MPAs above 170 cells/µl indicated LA thrombus with a high sensitivity of 93% and a specificity of 73% (OR 62, 95% CI. 6.9–557.2, p < 0.001) in patients with AF, whereas the D-dimer lost their quality as independent indicator by using the conventional cut-off of 0.5 mg/l within the regression analysis. MPAs, as well as the D-dimer, correlated significantly negatively with the flow in the LAA measured during TEE. The content of MPAs, sCD40L, and D-dimer, but not sP-selectin showed an increased dependence on LA thrombus in patients with AF. In our study group, MPAs showed the best diagnostic test accuracy of the compared platelet markers. The different results of the examined platelet activation markers could be an indication of diverse mechanisms of LA thrombus in AF. Further studies should evaluate whether determination of MPAs in clinical routine may suffice to indicate the presence of LA thrombus in patients with AF.

The endothelial nitric oxide synthase cofactor tetrahydrobiopterin shields the remote myocardium from apoptosis after experimental myocardial infarction in vivo

BACKGROUND Following myocardial infarction (MI), apoptosis occurs early in the remote myocardium and contributes to the processes of myocardial remodelling. Increased nitrosative stress is a well-known and potent inductor of myocardial apopto¬sis. Excess activation of endothelial nitric oxide synthase (eNOS) increases its uncoupling potential and results in nitrosative stress via formation of peroxynitrite. However, the pathophysiological role of eNOS signalling in the remote myocardium after MI is as yet undefined. AIM The impact of eNOS activation on pro- and anti-apoptotic signalling in the remote myocardium and the influence of pretreatment with the eNOS cofactor tetrahydrobiopterin (BH4) on eNOS activation, nitrosative stress level, and apoptosis induction and execution were studied in a rat MI model in vivo. RESULTS Twenty-four hours after anterior MI, eNOS activity in animals treated with left anterior descending coronary artery ligation (LIG) significantly increased in the posterior left ventricular (LV) myocardium as did protein nitrosylation when com¬pared to sham treatment. This was paralleled by induction of apoptosis via the extrinsic and intrinsic pathways. Moreover, anti-apoptotic signalling via protein kinase B/Akt and glycogen synthase-kinase 3 beta was suppressed. Notably, pretreatment with the eNOS cofactor BH4 reduced eNOS activation, prevented excess protein nitrosylation, blunted apoptosis induction, facilitated anti-apoptotic signalling, and eventually prevented apoptosis execution. CONCLUSIONS Here we showed that 24 h after experimental MI in rats in vivo, apoptosis was induced in the posterior non-in¬farcted LV wall. Evidence is presented that pretreatment with the eNOS cofactor BH4 resulted in less nitrosative stress and weakened apoptotic processes, although the stabilisers contained did participate in this phenomenon. Because apoptosis is a crucial component of myocardial remodelling, influencing eNOS signalling might be an interesting pharmacological target for the development of novel anti-remodelling therapies.

Regulation of circulating chromogranin B levels in heart failure

Abstract Background: Chromogranin B (CGB) regulates B-type natriuretic peptide (BNP) production. Circulating CGB levels are elevated in heart failure (HF) animal models and HF patients, but also increase in healthy individuals in response to physical activity. Therefore, CGB seems to integrate information from myocardial stress and systemic neuro-endocrine activation. Substantial gaps remain in our understanding of CGB regulation in HF. Methods and results: We conducted a retrospective registry study including 372 patients. CGB and N-terminal pro-BNP (NT-proBNP) plasma levels were assessed in acute HF and chronic valvular HF patients and controls. CGB levels were significantly increased in acute HF and chronic valvular HF, but significantly higher in the latter. Patients in chronic valvular HF with severe mitral regurgitation (cHF-MR) showed significantly higher CGB levels than patients in chronic valvular HF with severe aortic stenosis. CGB levels progressively increased with worsening NYHA functional status and were moderately correlated to NT-proBNP, but independent of left ventricular (LV) ejection fraction (LVEF), LV mass, age and body weight. Finally, cHF-MR patients showed significant reductions of CGB levels after interventional mitral valve repair. Conclusion: CGB is a promising emerging biomarker in HF patients with unique potential to integrate information from myocardial stress and neuro-endocrine activation.

Letter by Heidrich et al Regarding Article, “A Word of Caution: Risk of Device Erosion After Percutaneous Treatment of Atrial Septal Defect in Patients With Dilated Aortic Root”

In this interesting report, Dardas et al1 describe another case of a rare yet potentially life-threatening complication of interventional atrial septal defect closure with a 20-mm Amplatzer septal occluder device. Transesophageal echocardiography revealed a 15-mm atrial septal defect complicated by a deficient aortic rim and a bicuspid aortic valve, along with aortic root dilation (42 mm). At the routine 6-month follow-up, transesophageal echocardiography showed device perforation into the aortic root. We previously described a series of 2 patients who underwent primarily uncomplicated interventional patent foramen ovale closure by a Cardia Star …

Acute coronary syndrome and single coronary artery ostium

We report the case of a 44-year-old man with a medical history of arterial hypertension and nicotine abuse (10 pack years) presenting with persistent chest pain to our emergency department. Cardiac markers were elevated (hsTrop T 112 ng/L; CK 4.33 μkat/L; CK-MB 0.67 μkat/L) and eletrocardiogram impressed with biphasic T waves in lead V1 to V4 (Fig. 1). Two-dimensional Doppler echocardiography showed normal biventricular function without regional wall motion disturbances. Left heart catheterisation revealed a single coronary artery from the left sinus valsalva with a right coronary artery (RCA) arising from the left main stem (LMS). Furthermore, a high grade stenosis of proximal left anterior descending (LAD) was displayed and percutaneous coronary intervention with implantation of 2 drug eluting stents was successfully performed (Figs. 2, 3). To document the extent of myocardial infarction, and to exclude a malignant course of RCA between aorta and pulmonary artery, the patient was referred to 3T cardiac magnetic resonance (MR) with an 8-channel cardiac coil. Late gadolinium enhancement (LGE) sequences presented small septal subendocardial contrast enhancement indicating myocardial fibrosis after myocardial infarction (Fig. 4). Using a 3D whole heart Fat Sat FIESTA technique sequence, RCA arising from the LMS was confirmed. But because of the 3T MR-specific low spatial resolution, RCA course could not be traced accurately (Fig. 5). Therefore, a coronary 128-slice dual-source computed tomography (CT) was carried out showing RCA running between aorta, left and right atrium and not interarterially (Figs. 6–8). Further conservative course of the patient proceeded without complications. This case demonstrates an isolated single coronary artery as a rare congenital anomaly occurring with an incidence of 0.02%. Although often being asymptomatic, this anomaly can also appear with a sudden cardiac event, as in this patient, or with a malignant course. Therefore, the necessity for multimodal imaging to illustrate the true anatomic conditions should be underlined. Additionally, the still existing difficulties of 3T MR coronary angiography in daily practice and the resolution advantages of CT in imaging coronary arteries were highlighted.