L. Christian Napp

Clinical Features and Outcomes of Takotsubo (Stress) Cardiomyopathy

BACKGROUND The natural history, management, and outcome of takotsubo (stress) cardiomyopathy are incompletely understood. METHODS The International Takotsubo Registry, a consortium of 26 centers in Europe and the United States, was established to investigate clinical features, prognostic predictors, and outcome of takotsubo cardiomyopathy. Patients were compared with age- and sex-matched patients who had an acute coronary syndrome. RESULTS Of 1750 patients with takotsubo cardiomyopathy, 89.8% were women (mean age, 66.8 years). Emotional triggers were not as common as physical triggers (27.7% vs. 36.0%), and 28.5% of patients had no evident trigger. Among patients with takotsubo cardiomyopathy, as compared with an acute coronary syndrome, rates of neurologic or psychiatric disorders were higher (55.8% vs. 25.7%) and the mean left ventricular ejection fraction was markedly lower (40.7±11.2% vs. 51.5±12.3%) (P<0.001 for both comparisons). Rates of severe in-hospital complications including shock and death were similar in the two groups (P=0.93). Physical triggers, acute neurologic or psychiatric diseases, high troponin levels, and a low ejection fraction on admission were independent predictors for in-hospital complications. During long-term follow-up, the rate of major adverse cardiac and cerebrovascular events was 9.9% per patient-year, and the rate of death was 5.6% per patient-year. CONCLUSIONS Patients with takotsubo cardiomyopathy had a higher prevalence of neurologic or psychiatric disorders than did those with an acute coronary syndrome. This condition represents an acute heart failure syndrome with substantial morbidity and mortality. (Funded by the Mach-Gaensslen Foundation and others; ClinicalTrials.gov number, NCT01947621.).

GDF-15 is an inhibitor of leukocyte integrin activation required for survival after myocardial infarction in mice

Inflammatory cell recruitment after myocardial infarction needs to be tightly controlled to permit infarct healing while avoiding fatal complications such as cardiac rupture. Growth differentiation factor-15 (GDF-15), a transforming growth factor-β (TGF-β)–related cytokine, is induced in the infarcted heart of mice and humans. We show that coronary artery ligation in Gdf15-deficient mice led to enhanced recruitment of polymorphonuclear leukocytes (PMNs) into the infarcted myocardium and an increased incidence of cardiac rupture. Conversely, infusion of recombinant GDF-15 repressed PMN recruitment after myocardial infarction. In vitro, GDF-15 inhibited PMN adhesion, arrest under flow and transendothelial migration. Mechanistically, GDF-15 counteracted chemokine-triggered conformational activation and clustering of β2 integrins on PMNs by activating the small GTPase Cdc42 and inhibiting activation of the small GTPase Rap1. Intravital microscopy in vivo in Gdf15-deficient mice showed that Gdf-15 is required to prevent excessive chemokine-activated leukocyte arrest on the endothelium. Genetic ablation of β2 integrins in myeloid cells rescued the mortality of Gdf15-deficient mice after myocardial infarction. To our knowledge, GDF-15 is the first cytokine identified as an inhibitor of PMN recruitment by direct interference with chemokine signaling and integrin activation. Loss of this anti-inflammatory mechanism leads to fatal cardiac rupture after myocardial infarction.

Evaluation of postnatal arteriogenesis and angiogenesis in a mouse model of hind-limb ischemia

Blood vessel growth in adult organisms involves the following two fundamental processes: angiogenesis, the proliferation and extension of capillary networks; and arteriogenesis, the growth of functional arteries. We provide a protocol for the evaluation of postnatal arteriogenesis and angiogenesis in a mouse model of hind-limb ischemia. Surgical ligation of the femoral artery at a specific site triggers arteriogenesis of small, pre-existing collateral arteries into functional conduit vessels proximally and ischemic angiogenesis distally. The vascular response to hind-limb ischemia can be readily evaluated by laser Doppler-based perfusion measurements, histological quantification of arteriogenesis and angiogenesis or whole-mount visualization of arteries in limb muscles. Depending on the experimental design, the protocol takes between 4 and 29 d to complete; however, the net working time is about 2 d per mouse. The concurrent and specific analysis of postnatal angiogenesis and arteriogenesis in the same animal is a unique feature of the protocol.

Myeloid-derived growth factor (C19orf10) mediates cardiac repair following myocardial infarction

Paracrine-acting proteins are emerging as a central mechanism by which bone marrow cell–based therapies improve tissue repair and heart function after myocardial infarction (MI). We carried out a bioinformatic secretome analysis in bone marrow cells from patients with acute MI to identify novel secreted proteins with therapeutic potential. Functional screens revealed a secreted protein encoded by an open reading frame on chromosome 19 (C19orf10) that promotes cardiac myocyte survival and angiogenesis. We show that bone marrow–derived monocytes and macrophages produce this protein endogenously to protect and repair the heart after MI, and we named it myeloid-derived growth factor (MYDGF). Whereas Mydgf-deficient mice develop larger infarct scars and more severe contractile dysfunction compared to wild-type mice, treatment with recombinant Mydgf reduces scar size and contractile dysfunction after MI. This study is the first to assign a biological function to MYDGF, and it may serve as a prototypical example for the development of protein-based therapies for ischemic tissue repair.

Molecular Imaging of the Chemokine Receptor CXCR4 After Acute Myocardial Infarction.

OBJECTIVES An assay for molecular imaging of myocardial CXCR4 expression was evaluated, in order to obtain mechanistic insights noninvasively based on quantitative positron emission tomography (PET). BACKGROUND The chemokine receptor CXCR4 has emerged as a therapeutic target after acute myocardial infarction (AMI), because of its role in inflammatory and progenitor cell recruitment. METHODS PET with the specific CXCR4 ligand, gallium-68 ((68)Ga)-pentixafor, was performed in mice (n = 53) and compared with ex vivo autoradiography, immunohistochemistry, and left ventricular flow cytometry. In addition, 12 patients were imaged at 2 to 8 days after AMI. RESULTS In mice, (68)Ga-pentixafor identified regional CXCR4 upregulation in the infarct region, peaking at 3 days (infarct/remote [I/R] ratio 1.5 ± 0.2 at 3 days vs. 1.2 ± 0.3 at 7 days; p = 0.03), corresponding to a flow cytometry-based peak of CD45+ leukocytes and immunohistochemical detection of CD68+ macrophages and Ly6G+ granulocytes. Blockade with the CXCR4 antagonist AMD3100 abolished the signal. No specific uptake was found in sham-operated or control animals. Long-term treatment with oral enalapril attenuated the CXCR4 signal (I/R 1.2 ± 0.2 at 3 days and 1.0 ± 0.0.1 at 7 days; p = 0.01 vs. untreated). Patients showed variable degrees of CXCR4 upregulation in the infarct region. No single clinical parameter allowed for prediction of CXCR4 signal strength. At multivariate analysis, a combination of infarct size and time after reperfusion predicted the CXCR4 infarct signal (rmultiple = 0.73; p = 0.03). Infarct signal in the myocardium was paralleled by elevated pentixafor uptake in bone marrow (r = 0.61; p = 0.04), which highlighted systemic interactions. CONCLUSIONS Targeted PET imaging with (68)Ga-pentixafor identifies the global and regional CXCR4 expression pattern in myocardium and systemic organs. CXCR4 upregulation after AMI coincides with inflammatory cell infiltration, but shows interindividual variability in patients. This may have implications for the response to CXCR4- or other inflammation-targeted therapy, and for subsequent ventricular remodeling.

Cannulation strategies for percutaneous extracorporeal membrane oxygenation in adults

Extracorporeal membrane oxygenation (ECMO) has revolutionized treatment of severe isolated or combined failure of lung and heart. Due to remarkable technical development the frequency of use is growing fast, with increasing adoption by interventional cardiologists independent of cardiac surgery. Nevertheless, ECMO support harbors substantial risk such as bleeding, thromboembolic events and infection. Percutaneous ECMO circuits usually comprise cannulation of two large vessels (‘dual’ cannulation), either veno-venous for respiratory and veno-arterial for circulatory support. Recently experienced centers apply more advanced strategies by cannulation of three large vessels (‘triple’ cannulation), resulting in veno-veno-arterial or veno-arterio-venous cannulation. While the former intends to improve drainage and unloading, the latter represents a very potent method to provide circulatory and respiratory support at the same time. As such triple cannulation expands the field of application at the expense of increased complexity of ECMO systems. Here, we review percutaneous dual and triple cannulation strategies for different clinical scenarios of the critically ill. As there is no unifying terminology to date, we propose a nomenclature which uses “A” and all following letters for supplying cannulas and all letters before “A” for draining cannulas. This general and unequivocal code covers both dual and triple ECMO cannulation strategies (VV, VA, VVA, VAV). Notwithstanding the technical evolution, current knowledge of ECMO support is mainly based on observational experience and mostly retrospective studies. Prospective controlled trials are urgently needed to generate evidence on safety and efficacy of ECMO support in different clinical settings.

Differences in the Clinical Profile and Outcomes of Typical and Atypical Takotsubo Syndrome: Data From the International Takotsubo Registry

IMPORTANCE Apical ballooning is broadly recognized as the classic form of takotsubo syndrome (TTS). Atypical subtypes of TTS also exist, which constitute about 20% of all cases. To date, clinical profile and course of atypical TTS types have rarely been studied. OBJECTIVE To characterize the clinical profile and outcomes of typical vs atypical types of TTS in a large patient cohort. DESIGN, SETTING, AND PARTICIPANTS Records of 1750 patients from the International Takotsubo Registry, comprising 26 participating cardiovascular centers in 9 different countries, were reviewed and data on clinical profile and outcomes collected from January 1, 2011, to December 31, 2014. MAIN OUTCOMES AND MEASURES Clinical characteristics and in-hospital as well as long-term outcomes were assessed. RESULTS Of 1750 patients diagnosed with TTS between 1998 and 2014, a total of 1430 (81.7%) presented with apical TTS (defined as typical TTS) and 320 (18.3%) with midventricular, basal, or focal TTS (all defined as atypical TTS). Patients with atypical TTS were younger than those with typical TTS (mean [SD], 62.5 [13.3] vs 67.3 [12.9] years; P < .001). Brain natriuretic peptide levels on admission were lower (median factor increase of the upper limit of normal, 4.18 vs 6.59; P = .02) and left ventricular ejection fraction was higher (mean [SD], 43.4% [10.7%] vs 40.6% [12.0%]; P < .001) in patients with atypical than those with typical forms of TTS. ST-segment depression was more prevalent in patients with atypical TTS (31 of 286 [10.8%] vs 90 of 1292 [7.0%]; P = .03), while ST-segment elevation was found more frequently in patients with typical TTS (593 of 1292 [45.9%] vs 97 of 286 [33.9%]; P < .001). Patients with atypical TTS more often had neurologic disorders than those with typical TTS (81 of 274 [29.6%] vs 286 of 1251 [22.9%]; P = .02). While in-hospital mortality was comparable between patients with atypical and typical TTS (10 of 320 [3.1%] vs 62 of 1430 [4.3%]; P = .32), the atypical forms showed a favorable outcome at 1 year (P = .01). However, after adjustment for confounders, only left ventricular ejection fraction less than 45%, atrial fibrillation, and neurologic disease, but not the type of TTS, were independent predictors. After 1 year, patients with both types of TTS showed a similar prognosis at long-term follow-up. CONCLUSIONS AND RELEVANCE Atypical TTS has different characteristics than typical TTS, including younger age of onset, more frequent ST-segment depression, higher prevalence of neurologic diseases, less pronounced reduction in left ventricular ejection fraction, and lower brain natriuretic peptide values on admission. Outcomes are comparable between patients with both types after adjustment for confounders, suggesting that both should be equally monitored.

Provisional vs. two-stent technique for unprotected left main coronary artery disease after ten years follow up: A propensity matched analysis

AIMS There is uncertainty on which stenting approach confers the best long-term outlook for unprotected left main (ULM) bifurcation disease. METHODS AND RESULTS This is a non-randomized, retrospective study including all consecutive patients with 50% stenosis of the left main involving at least 1 of the arteries stemming from the left main treated with drug-eluting stents (DES) in 9 European centers between 2002 and 2004. Patients were divided into two groups: those treated with provisional stentings vs. those treated with two stent strategy. The outcomes of interest were 10-year rates of target lesion revascularization (TLR), major adverse cardiac events (MACE), and their components (cardiovascular death, myocardial infarction [MI], or repeat revascularization), along with stent thrombosis (ST). A total of 285 patients were included, 178 (62.5%) in the provisional stenting group and 87 (37.5%) in the two stent group. After 10 years, no differences in TLR were found at unadjusted analysis (19% vs 25%, p>0.05) nor after propensity score matching (25% vs 28%, p>0.05). Similar rates of MACE (60% vs 66%, p>0.05), death (34% vs 43%, p>0.05), MI (9% vs 14%, p>0.05) and ST were also disclosed at propensity-based analysis. CONCLUSION Even after 10 year follow-up, patients treated with provisional stenting on left main showed comparable rates of target lesion revascularization compared to two stent strategy.

Regulation of monocyte cell fate by blood vessels mediated by Notch signalling

A population of monocytes, known as Ly6Clo monocytes, patrol blood vessels by crawling along the vascular endothelium. Here we show that endothelial cells control their origin through Notch signalling. Using combinations of conditional genetic deletion strategies and cell-fate tracking experiments we show that Notch2 regulates conversion of Ly6Chi monocytes into Ly6Clo monocytes in vivo and in vitro, thereby regulating monocyte cell fate under steady-state conditions. This process is controlled by Notch ligand delta-like 1 (Dll1) expressed by a population of endothelial cells that constitute distinct vascular niches in the bone marrow and spleen in vivo, while culture on recombinant DLL1 induces monocyte conversion in vitro. Thus, blood vessels regulate monocyte conversion, a form of committed myeloid cell fate regulation.

Takotsubo Syndrome: Underdiagnosed, Underestimated, but Understood?

Takotsubo syndrome (TTS) is an acute heart failure syndrome that predominantly affects post-menopausal women. It is characterized by substantial morbidity and mortality, which equal those of acute coronary syndromes (ACS) and are still underappreciated [(1)][1]. TTS and ACS share many clinical