Successful weaning from veno-arterial ECMO and Impella2.5 by veno-venous and arterial ECMO (v-ECPELLA) for a patient with acute myocardial infarction complicated by severe lung injury.

The Impella™ (Abiomed, Danvers, MA, USA) is a percutaneous left ventricular assist device and is concurrently used with veno-arterial extracorporeal membrane oxygenation (VA ECMO). However, concomitantly using these two devices makes identifying the mixed zone of two opposite blood flows difficult. We report the case of an 80-year-old man with ST-elevation myocardial infarction and cardiopulmonary arrest. Emergent coronary angiography showed 99% stenosis in the left main trunk. A drug-eluting stent was placed under support of VA ECMO and the Impella2.5 for cardiogenic shock. During this support, antegrade deoxygenated blood enhanced by the Impella was sent to the right radial artery. Inadequate oxygenated blood was delivered through the native lung, which was damaged by cardiopulmonary resuscitation. We decided to convert to veno-venous and arterial ECMO (V-VA ECMO) using additional venous cannulation as drainage. Returned oxygenated blood was sent to the inferior vena cava and femoral artery bilaterally for maintaining oxygenation in the pulmonary artery. In V-VA ECMO and the Impella (v-ECPELLA), we attempted weaning from VA ECMO by only clamping VA cannulation and switching to veno-venous ECMO. We restored the setting to VA ECMO after assessment of the systemic circulation. We successfully managed and weaned our patient from simultaneous use of VA ECMO and the Impella2.5 by using v-ECPELLA. .

Feasibility and safety of uninterrupted dabigatran therapy in patients undergoing ablation for atrial fibrillation.

OBJECTIVE: Uninterrupted oral warfarin strategy has become the standard protocol to prevent complications during catheter ablation (CA) for the treatment of atrial fibrillation (AF). However, little is known about the safety and efficacy of uninterrupted dabigatran therapy in patients undergoing CA for AF. Therefore, this study investigated the safety and efficacy of uninterrupted dabigatran therapy and compared the findings with those for uninterrupted warfarin therapy. METHODS: Bleeding and thromboembolic events during the periprocedural period were evaluated in 363 consecutive patients who underwent CA for AF at Nagoya University Hospital, and received uninterrupted dabigatran (n=173) or uninterrupted warfarin (n=190) for periprocedural anticoagulation. RESULTS: A total of 27 (7%) patients experienced either bleeding or thromboembolic complications. Major bleeding complications occurred in 2 (1%) patients in the dabigatran group (DG) and 2 (1%) patients in the warfarin group (WG). Eight (5%) patients in the DG and 9 (5%) patients in the WG experienced groin hematoma, a type of minor bleeding complication. Meanwhile, no patient in the DG and 1 (1%) in the WG developed cerebral ischemic stroke. Overall, there was no significant difference between the groups for any category. The activated partial thromboplastin time (APTT) independently predicted periprocedural complications in the DG. CONCLUSION: Uninterrupted dabigatran therapy in CA for AF thus may be a safe and effective anticoagulant therapy, and appears to be closely similar to continuous warfarin; however, it is essential to pay close attention to the APTT values when using dabigatran during CA.

Impact of cardiac resynchronization therapy-defibrillator implantation on the association between body mass index and prognosis in patients with heart failure.

PURPOSE: This study aimed to examine the association between body mass index (BMI) and prognosis in heart failure patients after cardiac resynchronization therapy-defibrillator (CRT-D) implantation. METHODS: We retrospectively investigated 125 patients (33 overweight [BMI ≥25 kg/m(2)], 75 normal weight [BMI 18.5-24.9 kg/m(2)], and 17 underweight patients [BMI <18.5 kg/m(2)]) who underwent CRT-D implantation. The clinical outcome endpoints were all-cause death and appropriate shock therapy. RESULTS: During the follow-up period (mean 3.1 ± 1.8 years), 23 patients died (1 [3.0 %] overweight, 17 [22.7 %] normal weight, and 5 [29.4 %] underweight patients), and appropriate shock events were observed in 14 patients (2 [6.1 %] overweight, 10 [13.3 %] normal weight, and 2 [11.8 %] underweight patients). All patients survived shock therapy. After adjusting for confounding factors, overweight patients had significantly fewer outcomes relating to all-cause death and appropriate shock events (hazard ratio 0.27, 95 % confidence interval 0.08-0.91, p = 0.034) than normal weight patients. However, the prognostic difference between overweight and normal weight patients could be diminished as a result of the successful shock therapies (p = 0.067). Additionally, prognosis did not differ between overweight and normal weight patients among the responders, but did differ among the non-responders. The underweight patients had a poorer prognosis after CRT-D implantation compared with the other groups. CONCLUSIONS: Although high BMI was associated with better outcomes among heart failure patients with CRT-D implantations, the difference in the prognosis between overweight and normal weight patients was reduced because of defibrillator therapy and the improvement in cardiac function provided by CRT-D implantation.

Alogliptin, a dipeptidyl peptidase-4 inhibitor, regulates the atrial arrhythmogenic substrate in rabbits.

BACKGROUND: Dipeptidyl peptidase-4 (DPP-4) inhibitors were recently reported to have cardioprotective effects via amelioration of ventricular function. However, the role of DPP-4 inhibition in atrial remodeling, especially of the arrhythmogenic substrate, remains unclear. OBJECTIVE: We investigated the effects of a DPP-4 inhibitor, alogliptin, on atrial fibrillation (AF) in a rabbit model of heart failure caused by ventricular tachypacing (VTP). METHODS: Rabbits subjected to VTP at 380 bpm for 1 or 3 weeks, with or without alogliptin treatment, were assessed using echocardiography, electrophysiology, histology, and immunoblotting and compared with nonpaced animals. RESULTS: VTP rabbits exhibited increased duration of atrial burst pacing-induced AF, whereas administration of alogliptin shortened this duration by 73%. The extent of atrial fibrosis after VTP was reduced by 39% in the alogliptin-treated group. VTP rabbits treated with alogliptin displayed a 1.6-fold increase in left atrial myocardial capillary density compared with nontreated rabbits. A 2-fold increase in endothelial nitric oxide synthase (eNOS) phosphorylation was observed in the left atrium of alogliptin-treated rabbits compared with nontreated rabbits. Moreover, a nitric oxide synthase inhibitor (N(ω)-nitro-l-arginine methyl ester) blocked the beneficial effects of alogliptin on AF duration, fibrosis, and capillary density. CONCLUSION: Alogliptin shortened the duration of AF caused by VTP-induced fibrotic atrial tissue by augmenting atrial angiogenesis and activating eNOS. Our findings suggest that DPP-4 inhibitors may be useful in the prevention of heart failure-induced AF.

Efficacy and safety of apixaban in the patients undergoing the ablation of atrial fibrillation.

INTRODUCTION: Apixaban, a factor Xa (FXa) inhibitor, is a new oral anticoagulant for stroke prevention in atrial fibrillation (AF). However, little is known about its efficacy and safety as a periprocedural anticoagulant therapy for patients who had undergone catheter ablation (CA) for AF. METHODS AND RESULTS: We evaluated 342 consecutive patients who underwent CA for AF between April 2013 and March 2014 and received apixaban (n = 105) and warfarin (n = 237) for uninterrupted periprocedural anticoagulation. We retrospectively investigated the occurrence of bleeding and thromboembolic complications during the procedural period and compared them between the apixaban group (AG) and warfarin group (WG). Thromboembolic complications occurred in one (0.4%) patient in the WG. Major and minor bleeding complications occurred in one (1%) and four (4%) patients in the AG, and three (1%) and 12 (5%) patients in the WG. No significant difference in complications was observed between the AG and WG. Of importance, adverse event rates did not differ between the two groups after adjusting by a propensity score analysis. In preoperative tests of blood coagulation, there were significant differences in the prothrombin time, activated partial thromboplastin time, FXa activity, and prothrombin fragment 1 + 2 (F1+2) levels between the AG and WG. CONCLUSION: The use of apixaban during the periprocedural period of AF ablation seemed as efficacious and safe as warfarin.

Clinical characteristics and predictors of super-response to cardiac resynchronization therapy: a combination of predictive factors.

BACKGROUND: Patients with greater improvement of cardiac function after cardiac resynchronization therapy (CRT) implantation are identified as "super-responders." However, it remains unclear which kind of preimplant assessments could accurately predict outcomes after CRT. Thus, we aimed to examine the essential predicting factors for super-response to CRT, and to construct an accurate predictable model. METHODS: We retrospectively analyzed the CRT patients who underwent implantation at Nagoya University Hospital. Super-responders are defined as those who show a relative reduction in left ventricular end-systolic volume ≥30% after 6 months of CRT. RESULTS: Eighty patients (mean age, 67.8 ± 10.2 years) were included. Twenty-two patients received upgrading procedure to CRT implantation. Six months after the implantation, 29 patients (36%) were super-responders. Multiple logistic regression analysis shows that consistent right ventricular pacing with a previous device (odds ratio [OR] 7.28, 95% confidence interval [CI] 1.52-34.9; P = 0.013), lack of prior history of ventricular arrhythmia (OR 5.32, 95% CI 1.52-18.6; P = 0.009), and smaller left atrial diameter (LAD) (OR 0.92, 95% CI 0.86-0.98; P = 0.014) are independent predictors for CRT super-responders. The use of a combination of these predictive factors could increase the certainty with which a greater response to CRT is predicted and the presence of such a combination could improve prognosis. CONCLUSION: Greater response to biventricular pacing occurs more frequently in patients with consistent right ventricular pacing, lack of prior history of ventricular arrhythmia, and smaller LAD. An association between patient background characteristics and a super-response to CRT was also identified.

Acute improvement of left ventricular relaxation as a predictor of volume reduction after cardiac resynchronization therapy: a pilot study assessing the value of left ventricular hemodynamic parameter.

BACKGROUND: Cardiac resynchronization therapy (CRT) improves cardiac function, but CRT recipients with advanced heart failure (HF) do not always respond well. Because the best parameters for the prediction of CRT response are not established, we investigated whether improvement of invasive left ventricular (LV) hemodynamic diastolic parameters could identify CRT responders. METHODS: A total of 34 consecutive patients (age, 69 ± 9 years; 70% men) who received CRT devices for HF were assessed as to whether acute invasive hemodynamic parameters with and without CRT function could predict LV volume responders. RESULTS: These patients demonstrated an improvement in LV dP/dtmax (11.1 ± 11.7%), LV dP/dtmin (4.6 ± 12.1%), and tau (3.7 ± 11.6%) by biventricular pacing. Nineteen patients (55%) were classified as CRT responders, which was defined by a >15% decrease in LV end-systolic volume (ESV) at the 6-month follow-up evaluation. The area under the receiver operator characteristic curve to detect CRT volume response was 0.93 for the shortening of tau, which was superior to any other hemodynamic parameter. The multivariate analysis revealed that this improvement in tau was the strongest predictive factor for identifying CRT volume responders. Of note, the magnitude of tau shortening during biventricular pacing was significantly correlated with the reduction in LVESV at the 6-month follow-up evaluation. CONCLUSIONS: The extent of acute improvement in LV isovolumic relaxation time, as assessed by tau, was associated with favorable response to CRT. The assessment of invasive diastolic function could provide valuable information about CRT volume response.

Comparison of the change in the dimension of the pulmonary vein ostia immediately after pulmonary vein isolation for atrial fibrillation-open irrigated-tip catheters versus non-irrigated conventional 4 mm-tip catheters.

INTRODUCTION: A difference in the lesion formation between open irrigated-tip (OITC) and non-irrigated 4-mm-tip catheters (NITC) may result in a difference in the dimension of the pulmonary vein (PV) ostia after PV isolation of atrial fibrillation (AF). This study evaluated the difference using intracardiac echocardiography (ICE) before and immediately after an extensive encircling PV isolation (EPVI) with an OITC and with an NITC. METHODS AND RESULTS: We studied 100 consecutive patients (OITC group, 54; NITC group, 46) who received EPVI. Changes in the vessel, lumen, and wall thickness areas of the PVs were evaluated at the PV ostia by ICE. There were no significant differences in the baseline characteristics and acute success rate of the EPVI between the OITC and NITC groups. The energy delivered to achieve EPVI was higher in the OITC group than that in the NITC group (34,967 ± 13,222 J vs. 28,300 ± 10,614 J; p=0.01). After the ablation, the reduction in the vessel and lumen cross-sectional areas was significantly smaller in the OITC group than that in the NITC group (-9.05 ± 28.4 % vs. -21.2 ± 28.8 %, p<0.001; -8.76 % vs. -17.7 ± 26.9 %, p=0.003). The wall thickness area slightly decreased in the OITC group, but increased in the NITC group (-2.96 ± 38.4 % vs. 10.5 ± 76.6 %, p=0.591). During a median follow-up of 234 days, there was no significant difference in the AF recurrence after the initial ablation procedure between the two groups. CONCLUSION: Greater PV ostial narrowing occurred with the NITC than OITC immediately after the EPVI. PV ostial wall edema was noted with only the NITC. These findings suggested that an OITC might reduce any acute PV narrowing and wall edema as compared with an NITC.

Impact of sitagliptin on carotid intima-media thickness in patients with coronary artery disease and impaired glucose tolerance or mild diabetes mellitus.

Sitagliptin has been widely used for the treatment of diabetes and shown recently to have beneficial pleiotropic outcomes on cardiovascular systems in experimental studies. However, little is known about the influence of sitagliptin on atherosclerosis-related cardiovascular diseases in a clinical setting. This study examined the effect of sitagliptin on carotid intima-media thickness (IMT). A total of 76 patients with clinically stable and documented coronary artery disease, who were newly diagnosed with impaired glucose tolerance or mild type 2 diabetes mellitus, were allocated, randomly, to receive either sitagliptin 100 mg/day or the placebo control. Common carotid IMT, glucose profiles, glycosylated hemoglobin (HbA1c), and lipid profiles were measured at baseline and repeated at 12 months. Sitagliptin-treated patients showed less IMT progression than the control group (p = 0.02). In addition, the sitagliptin group showed greater reductions in body weight (2.2%), 2-hour glucose levels on the 75-g oral glucose tolerance test (17.3%), HbA1c (4.7%), and low-density lipoprotein cholesterol levels (7.9%) from that at baseline. In conclusion, treatment with sitagliptin for 12 months was associated with a beneficial effect in the prevention of carotid IMT progression, compared with the diet control.

A novel electrocardiographic criterion for differentiating a left from right ventricular outflow tract tachycardia origin: the V2S/V3R index.

INTRODUCTION: Although several ECG criteria have been proposed for differentiating between left and right origins of idiopathic ventricular arrhythmias (VA) originating from the outflow tract (OT-VA), their accuracy and usefulness remain limited. This study was undertaken to develop a more accurate and useful ECG criterion for differentiating between left and right OT-VA origins. METHODS AND RESULTS: We studied OT-VAs with a left bundle branch block pattern and inferior axis QRS morphology in 207 patients who underwent successful catheter ablation in the right (RVOT; n = 154) or left ventricular outflow tract (LVOT; n = 53). The surface ECGs during the OT-VAs and during sinus beats were analyzed with an electronic caliper. The V2S/V3R index was defined as the S-wave amplitude in lead V2 divided by the R-wave amplitude in lead V3 during the OT-VA. The V2S/V3R index was significantly smaller for LVOT origins than RVOT origins (P < 0.001). The area under the curve (AUC) for the V2S/V3R index by a receiver operating characteristic analysis was 0.964, with a cut-off value of ≤1.5 predicting an LVOT origin with an 89% sensitivity and 94% specificity. In the AUC and accuracy, the V2S/V3R index was superior to any previously proposed ECG criteria in an analysis of all OT-VAs. This advantage of the V2S/V3R index over the V2 transition ratio and other indices also held true for a subanalysis of 77 OT-VAs with a lead V3 precordial transition. CONCLUSION: The V2S/V3R index outperformed other ECG criteria to differentiate left from right OT-VA origins independent of the site of the precordial transition.

Serum albumin levels predict clinical outcomes in chronic kidney disease (CKD) patients undergoing cardiac resynchronization therapy.

OBJECTIVE: A low level of serum albumin is common in chronic kidney disease (CKD) patients with heart failure (HF). Cardiac resynchronization therapy (CRT), a novel therapeutic option, improves cardiac performance in patients with severe HF. In addition, CKD has recently been found to be associated with outcomes after CRT; however, the associations of the serum albumin levels with adverse events and the long-term prognosis in CKD patients who have undergone CRT are unknown. In this study, we investigated whether the albumin levels can be used to the predict mortality rate and incidence of cardiovascular events in CKD patients treated with CRT. METHODS: A retrospective chart review was conducted in 102 consecutive CKD patients receiving a CRT device for the treatment of advanced HF. The long-term outcomes following device implantation were assessed according to the albumin levels. RESULTS: During a median follow-up of 2.6 years, 34 patients (33.3%) died and 66 patients (64.7%) experienced cardiovascular events. A Kaplan-Meier survival analysis revealed that the CKD patients with decreased albumin levels exhibited significantly higher rates of all-cause mortality and cardiovascular events, including hospitalization for progressive HF, than the CKD patients without hypoalbuminemia. Importantly, a multivariate Cox regression analysis of confounding factors showed a low serum albumin level to independently predict all-cause death and cardiovascular events. CONCLUSION: Hypoalbuminemia independently predicts cardiac morbidity and mortality in CKD patients receiving CRT. Assessing the albumin levels provides valuable information regarding the long-term prognosis in CKD patients who undergo CRT.

Clinical outcome of implantable cardioverter defibrillators with recalled and non-recalled leads in Japanese patients. Increased failure rate of the Sprint Fidelis lead.

BACKGROUND: In recent years, there has been a series of recalls of popular implantable cardioverter defibrillators leads, and several reports have demonstrated an increasing rate of failure of such leads over time in Caucasian patients. However, little is known about the performance of these leads in Asian patients. The aim of this study was to investigate the rate of failure of the recalled leads and the characteristics as compared with non-recalled leads in Japanese patients. METHODS AND RESULTS: A retrospective chart review was conducted in 214 patients (75 Sprint Fidelis, 8 Riata, and 131 Sprint Quattro leads) who underwent implantation and follow-up at Nagoya University Hospital. During the follow-up period, 14 Sprint Fidelis leads (19%) and 1 Riata lead (13%) failed, but no abnormality was found in the Sprint Quattro, non-recalled leads. Five patients (4 Sprint Fidelis and 1 Riata, 33% of lead failure patients) received inappropriate shocks. The 3-, 4-, and 5-year lead survival rates in Sprint Fidelis leads were 95.1% (95% confidence interval [CI]: 89.6%-100%), 89.8% (95% CI: 82.1%-97.6%), and 88.0% (95% CI: 79.6%-96.4%), respectively. A previous device implantation before Sprint Fidelis lead was the only significant predictor for lead fracture (hazard ratio, 5.33; 95% CI: 1.55-18.4; P=0.008). CONCLUSIONS: The rate of Sprint Fidelis lead failure continues to increase over time in Japanese patients.

Efficacy and safety of radiofrequency catheter ablation for atrial fibrillation in chronic hemodialysis patients.

BACKGROUND: Radiofrequency catheter ablation (RFCA) is increasingly performed for the treatment of atrial fibrillation (AF), but it is problematic because the use of anti-arrhythmic agents is largely restricted in patients undergoing hemodialysis (HD) therapy. However, little is known about the long-term clinical outcomes of AF after RFCA in HD patients. METHODS: Between 2002 and 2008, 16 HD patients (age: 63.8 ± 7.4 years, 75.0% men) underwent RFCA for AF at the Toyota Kosei Hospital. We investigated the long-term results and mortality of RFCA for AF in HD patients and compared them with those of 111 non-HD patients (age: 58.6 ± 10.0 years, 78.3% male) who received the same procedures. RESULTS: During the follow-up (64.3 ± 25.4 months in HD patients, 70.5 ± 20.2 months in non-HD patients) after the initial RFCA procedure, sinus rhythm was restored in 4 HD patients (25%) and in 45 non-HD patients (40.5%). Multiple procedures were performed in 12 HD patients and in 57 non-HD patients. After the final procedure, 13 HD patients (81.3%) and 92 non-HD patients (82.9%) were free of atrial arrhythmia and symptoms. Of importance, Kaplan-Meier analysis did not demonstrate any significant differences in the atrial arrhythmia-free rate after the last procedure between HD patients and the control group matched after propensity-score analysis despite higher all-cause mortality in HD patients than in non-HD patients. CONCLUSIONS: During 5-years of follow-up, the use of multiple RFCA procedures for AF in patients undergoing HD was favorable, whereas the use of a single procedure was disappointing. Multiple RFCA procedures can be an efficient approach to the treatment of AF in HD patients.

Mechanisms with clinical implications for atrial fibrillation-associated remodeling: cathepsin K expression, regulation, and therapeutic target and biomarker.

BACKGROUND: The cysteine protease cathepsin K (CatK) has been implicated in the pathogenesis of cardiovascular disease. We sought to determine the link between atrial fibrillation (AF) and plasma CatK levels and to investigate the expression of and therapeutic target for CatK in vivo and in vitro. METHODS AND RESULTS: Plasma CatK and extracellular matrix protein peptides (intact procollagen type I of N-terminal propeptide; carboxyl-terminal telopeptide of type I collagen [ICTP]) were measured in 209 consecutive patients with AF (paroxysmal AF, 146; persistent AF, 63) and 112 control subjects. In addition, the regulation of CatK expression was investigated in vivo and vitro. Patients with AF had higher plasma CatK and ICTP levels than did control subjects. Patients with persistent AF had higher levels of plasma CatK and ICTP than did patients with paroxysmal AF. CatK was correlated with ICTP concentration and left atrial diameter in all subjects. In rabbits, superoxide production, CatK activity, fibrosis, and the levels of atrial tissue angiotensin II, angiotensin type 1 receptor, gp91phox, phospho-p38 mitogen-activated protein kinase, and CatK were greater in those with tachypacing-induced AF than in controls, and these changes were reversed with angiotensin type 1 receptor antagonist. Olmesartan and mitogen-activated protein kinase inhibitor decreased the CatK expression induced by angiotensin II in rat neonatal myocytes. CONCLUSIONS: These data indicated that increased plasma CatK levels are linked with the presence of AF. Angiotensin type 1 receptor antagonist appears to be effective in alleviating atrial fibrosis in a rabbit AF model, partly reducing angiotensin type 1 receptor-p38mitogen-activated protein kinase-dependent and -independent CatK activation, thus preventing AF.

Cystatin C as a predictor of mortality and cardiovascular morbidity after cardiac resynchronization therapy.

BACKGROUND: Cardiac resynchronization therapy (CRT) has been reported to improve symptoms and cardiac performance in patients with severe heart failure (HF), but CRT recipients with advanced HF do not always experience improved mortality rates. Cystatin C has recently been involved in HF, but the association of serum cystatin C level with adverse events and long-term prognosis after CRT is unknown. This study investigated whether cystatin C level can predict mortality and cardiovascular events after CRT. METHODS AND RESULTS: A total of 117 consecutive patients receiving a CRT device for the treatment of advanced HF were assessed according to cystatin C level and long-term outcome after implantation of the device. Over a median follow-up of 3.2 years, 34 patients (29.1%) died and 59 patients (50.4%) developed cardiovascular events. Kaplan-Meier survival analysis indicated that elevated cystatin C level was significantly associated with higher all-cause mortality and prevalence of cardiovascular events, including hospitalization for progressive HF. After multivariate Cox regression analysis, serum cystatin C level and QRS duration, but not conventional echocardiographic parameters, were found to independently predict all-cause death or cardiovascular events. Of importance, only cystatin C level was an independent predictor of all-cause mortality after CRT. CONCLUSIONS: Cystatin C level independently predicts cardiac mortality or morbidity in patients receiving CRT. The assessment of cystatin C level could provide valuable information about long-term prognosis after CRT.

Adiponectin modulates oxidative stress-induced autophagy in cardiomyocytes.

Diastolic heart failure (HF) i.e., "HF with preserved ejection fraction" (HF-preserved EF) accounts for up to 50% of all HF presentations; however there have been no therapeutic advances. This stems in part from an incomplete understanding about HF-preserved EF. Hypertension is the major cause of HF-preserved EF whilst HF-preserved EF is also highly associated with obesity. Similarly, excessive reactive oxygen species (ROS), i.e., oxidative stress occurs in hypertension and obesity, sensitizing the heart to the renin-angiotensin-aldosterone system, inducing autophagic type-II programmed cell death and accelerating the propensity to adverse cardiac remodeling, diastolic dysfunction and HF. Adiponectin (APN), an adipokine, mediates cardioprotective actions but it is unknown if APN modulates cardiomyocyte autophagy. We tested the hypothesis that APN ameliorates oxidative stress-induced autophagy in cardiomyocytes. Isolated adult rat ventricular myocytes were pretreated with recombinant APN (30 µg/mL) followed by 1mM hydrogen peroxide (H2O2) exposure. Wild type (WT) and APN-deficient (APN-KO) mice were infused with angiotensin (Ang)-II (3.2 mg/kg/d) for 14 days to induced oxidative stress. Autophagy-related proteins, mTOR, AMPK and ERK expression were measured. H2O2 induced LC3I to LC3II conversion by a factor of 3.4±1.0 which was abrogated by pre-treatment with APN by 44.5±10%. However, neither H2O2 nor APN affected ATG5, ATG7, or Beclin-1 expression. H2O2 increased phospho-AMPK by 49±6.0%, whilst pretreatment with APN decreased phospho-AMPK by 26±4%. H2O2 decreased phospho-mTOR by 36±13%, which was restored by APN. ERK inhibition demonstrated that the ERK-mTOR pathway is involved in H2O2-induced autophagy. Chronic Ang-II infusion significantly increased myocardial LC3II/I protein expression ratio in APN-KO vs. WT mice. These data suggest that excessive ROS caused cardiomyocyte autophagy which was ameliorated by APN by inhibiting an H2O2-induced AMPK/mTOR/ERK-dependent mechanism. These findings demonstrate the anti-oxidant potential of APN in oxidative stress-associated cardiovascular diseases, such as hypertension-induced HF-preserved EF.

Follistatin-like 3 mediates paracrine fibroblast activation by cardiomyocytes.

Follistatins are extracellular inhibitors of the TGF-ß family ligands including activin A, myostatin and bone morphogenetic proteins. Follistatin-like 3 (FSTL3) is a potent inhibitor of activin signalling and antagonises the cardioprotective role of activin A in the heart. FSTL3 expression is elevated in patients with heart failure and is upregulated in cardiomyocytes by hypertrophic stimuli, but its role in cardiac remodelling is largely unknown. Here, we show that the production of FSTL3 by cardiomyocytes contributes to the paracrine activation of cardiac fibroblasts, inducing changes in cell adhesion, promoting proliferation and increasing collagen production. We found that FSTL3 is necessary for this response and for the induction of cardiac fibrosis. However, full activation requires additional factors, and we identify connective tissue growth factor as a FSTL3 binding partner in this process. Together, our data unveil a novel mechanism of paracrine communication between cardiomyocytes and fibroblasts that may provide potential as a therapeutic target in heart remodelling.

Identification of follistatin-like 1 by expression cloning as an activator of the growth differentiation factor 15 gene and a prognostic biomarker in acute coronary syndrome.

BACKGROUND: Growth differentiation factor 15 (GDF15) is a stress-responsive cytokine and biomarker that is produced after myocardial infarction and that is related to prognosis in acute coronary syndrome (ACS). We hypothesized that secreted proteins that activate GDF15 production may represent new ACS biomarkers. METHODS: We expressed clones from an infarcted mouse heart cDNA library in COS1 cells and assayed for activation of a luciferase reporter gene controlled by a 642-bp fragment of the mouse growth differentiation factor 15 (GDF15) gene promoter. We measured the circulating concentrations of follistatin-like 1 (FSTL1) and GDF15 in 1369 patients with ACS. RESULTS: One cDNA clone that activated the GDF15 promoter-luciferase reporter encoded the secreted protein FSTL1. Treatment with FSTL1 activated GDF15 production in cultured cardiomyocytes. Transgenic production of FSTL1 stimulated GDF15 production in the murine heart, whereas cardiomyocyte-selective deletion of FSTL1 decreased production of GDF15 in cardiomyocytes, indicating that FSTL1 is sufficient and required for GDF15 production. In ACS, FSTL1 emerged as the strongest independent correlate of GDF15 (partial R(2) = 0.26). A total of 106 patients died of a cardiovascular cause during a median follow-up of 252 days. Patients with an FSTL1 concentration in the top quartile had a 3.7-fold higher risk of cardiovascular death compared with patients in the first 3 quartiles (P < 0.001). FSTL1 remained associated with cardiovascular death after adjustment for clinical, angiographic, and biochemical variables. CONCLUSIONS: Our study is the first to use expression cloning for biomarker discovery upstream of a gene of interest and to identify FSTL1 as an independent prognostic biomarker in ACS.

Cardiac myocyte follistatin-like 1 functions to attenuate hypertrophy following pressure overload.

Factors secreted by the heart, referred to as "cardiokines," have diverse actions in the maintenance of cardiac homeostasis and remodeling. Follistatin-like 1 (Fstl1) is a secreted glycoprotein expressed in the adult heart and is induced in response to injurious conditions that promote myocardial hypertrophy and heart failure. The aim of this study was to investigate the role of cardiac Fstl1 in the remodeling response to pressure overload. Cardiac myocyte-specific Fstl1-KO mice were constructed and subjected to pressure overload induced by transverse aortic constriction (TAC). Although Fstl1-KO mice displayed no detectable baseline phenotype, TAC led to enhanced cardiac hypertrophic growth and a pronounced loss in ventricular performance by 4 wk compared with control mice. Conversely, mice that acutely or chronically overexpressed Fstl1 were resistant to pressure overload-induced hypertrophy and cardiac failure. Fstl1-deficient mice displayed a reduction in TAC-induced AMP-activated protein kinase (AMPK) activation in heart, whereas Fstl1 overexpression led to increased myocardial AMPK activation under these conditions. In cultured neonatal cardiomyocytes, administration of Fstl1 promoted AMPK activation and antagonized phenylephrine-induced hypertrophy. Inhibition of AMPK attenuated the antihypertrophic effect of Fstl1 treatment. These results document that cardiac Fstl1 functions as an autocrine/paracrine regulatory factor that antagonizes myocyte hypertrophic growth and the loss of ventricular performance in response to pressure overload, possibly through a mechanism involving the activation of the AMPK signaling axis.