Loss of CASK Accelerates Heart Failure Development.

[Figure: see text].

Reduction of radiation exposure during transcatheter edge-to-edge mitral valve repair.

BACKGROUND: Transcatheter mitral valve repair is an increasingly used therapy for mitral regurgitation which requires fluoroscopic guidance. Limiting radiation exposure during lengthy procedures is important for both patient and operator safety. This study aimed to investigate radiation dose during contemporary use of MitraClip implantation and the effects of a dose reduction program. METHODS: A total of 115 patients who underwent MitraClip implantation were prospectively enrolled in a single-center observational study. During the inclusion period, our institution adopted a radiation dose reduction program, comprising lowering of fluoroscopy pulse rate and image target dose. The first 58 patients were treated with conventional fluoroscopy settings, while the following 57 patients underwent the procedure with the newly implemented low dose protocol. RESULTS: Radiation dose area product significantly decreased after introduction of the low dose protocol (693 [366-1231] vs. 2265 [1517-3914] cGy·cm2 , p < 0.001). After correcting for fluoroscopy time, gender and body mass index, the low dose protocol emerged as a strong negative predictor of radiation dose (p < 0.001), reducing dose area product by 64% (95% confidence interval [57-70]). Device time, device success, and procedural safety did not differ between the normal dose and low dose group. Furthermore, the low dose protocol was not associated with an increased incidence of a combined endpoint consisting of death, repeat intervention, or heart surgery during 12 months follow-up. CONCLUSION: Reduction of radiation exposure during transcatheter mitral valve repair by 64% is feasible without affecting procedural success or safety.

Pericardiectomy for Constrictive Pericarditis: An Institution's 21 Years Experience.

BACKGROUND: The aim of this retrospective study was to evaluate our experience with the surgical pericardiectomy procedure for patients suffering from isolated severe constrictive pericarditis. METHODS: From 1995 to 2016, 39 patients underwent isolated pericardiectomy for constrictive pericarditis. Fifteen patients were excluded because of concomitant surgery. There were 31 male (79.5%) patients and 8 female (20.5%) patients, 28 to 76 years old (mean, 56.6 ± 13.6 years). The underlying etiologies were idiopathic pericarditis (74.5%), infection (10%), rheumatic disorders (8%), status post cardiac surgery (2.5%), tuberculosis (2.5%), and status post mediastinal irradiation (2.5%). RESULTS: Pericardiectomy was performed through midline sternotomy in all cases. Sixteen patients (41%) underwent pericardiectomy electively employing cardiopulmonary bypass with the heart beating, and 23 patients (59%) had surgery without extracorporeal circulation (ECC). The overall 30-day mortality rate was 50% if cardiopulmonary bypass was used (13.8% since 2007). If surgery was performed without a heart-lung machine, mortality was 0%. On-pump patients had a significantly longer intensive care unit (ICU) stay (12 ± 9 vs. 4 ± 4 days, p = 0.013). Likewise, the duration of mechanical ventilation was much longer (171 ± 246 vs. 21 ± 40 hours, p = 0.04). The hospital stay was comparable with 28 ± 10 and 24 ± 18 days (p = 0.21). CONCLUSION: The present study demonstrates that pericardiectomy, without the use of cardiopulmonary bypass as treatment for constrictive pericarditis, is a safe procedure with an excellent outcome in critically ill patients.

Sensing Cardiac Electrical Activity With a Cardiac Myocyte--Targeted Optogenetic Voltage Indicator.

RATIONALE: Monitoring and controlling cardiac myocyte activity with optogenetic tools offer exciting possibilities for fundamental and translational cardiovascular research. Genetically encoded voltage indicators may be particularly attractive for minimal invasive and repeated assessments of cardiac excitation from the cellular to the whole heart level. OBJECTIVE: To test the hypothesis that cardiac myocyte-targeted voltage-sensitive fluorescence protein 2.3 (VSFP2.3) can be exploited as optogenetic tool for the monitoring of electric activity in isolated cardiac myocytes and the whole heart as well as function and maturity in induced pluripotent stem cell-derived cardiac myocytes. METHODS AND RESULTS: We first generated mice with cardiac myocyte-restricted expression of VSFP2.3 and demonstrated distinct localization of VSFP2.3 at the t-tubulus/junctional sarcoplasmic reticulum microdomain without any signs for associated pathologies (assessed by echocardiography, RNA-sequencing, and patch clamping). Optically recorded VSFP2.3 signals correlated well with membrane voltage measured simultaneously by patch clamping. The use of VSFP2.3 for human action potential recordings was confirmed by simulation of immature and mature action potentials in murine VSFP2.3 cardiac myocytes. Optical cardiograms could be monitored in whole hearts ex vivo and minimally invasively in vivo via fiber optics at physiological heart rate (10 Hz) and under pacing-induced arrhythmia. Finally, we reprogrammed tail-tip fibroblasts from transgenic mice and used the VSFP2.3 sensor for benchmarking functional and structural maturation in induced pluripotent stem cell-derived cardiac myocytes. CONCLUSIONS: We introduce a novel transgenic voltage-sensor model as a new method in cardiovascular research and provide proof of concept for its use in optogenetic sensing of physiological and pathological excitation in mature and immature cardiac myocytes in vitro and in vivo.

Erythropoietin responsive cardiomyogenic cells contribute to heart repair post myocardial infarction.

The role of erythropoietin (Epo) in myocardial repair after infarction remains inconclusive. We observed high Epo receptor (EPOR) expression in cardiac progenitor cells (CPCs). Therefore, we aimed to characterize these cells and elucidate their contribution to myocardial regeneration on Epo stimulation. High EPOR expression was detected during murine embryonic heart development followed by a marked decrease until adulthood. EPOR-positive cells in the adult heart were identified in a CPC-enriched cell population and showed coexpression of stem, mesenchymal, endothelial, and cardiomyogenic cell markers. We focused on the population coexpressing early (TBX5, NKX2.5) and definitive (myosin heavy chain [MHC], cardiac Troponin T [cTNT]) cardiomyocyte markers. Epo increased their proliferation and thus were designated as Epo-responsive MHC expressing cells (EMCs). In vitro, EMCs proliferated and partially differentiated toward cardiomyocyte-like cells. Repetitive Epo administration in mice with myocardial infarction (cumulative dose 4 IU/g) resulted in an increase in cardiac EMCs and cTNT-positive cells in the infarcted area. This was further accompanied by a significant preservation of cardiac function when compared with control mice. Our study characterized an EPO-responsive MHC-expressing cell population in the adult heart. Repetitive, moderate-dose Epo treatment enhanced the proliferation of EMCs resulting in preservation of post-ischemic cardiac function.

Enhanced late INa induces proarrhythmogenic SR Ca leak in a CaMKII-dependent manner.

OBJECTIVE: Enhanced late Na current (late INa) induces Na-dependent Ca overload as well as proarrhythmogenic events on the cellular level that include spatio-temporally uncoordinated diastolic Ca release from the sarcoplasmic reticulum (SR) and delayed afterdepolarizations (DADs). The Ca/calmodulin-dependent protein kinase II (CaMKII) gets activated upon increases in [Ca]i and mediates diastolic SR Ca leak as well as DADs. RATIONALE: We hypothesized that increased late INa (in disease-comparable ranges) exerts proarrhythmogenic events in isolated ventricular mouse myocytes in a manner depending on CaMKII-dependent SR Ca leak. We further tested whether inhibition of disease-related late INa may reduce proarrhythmogenic SR Ca leak in myocytes from failing human hearts. METHODS: Ventricular myocytes were isolated from healthy wildtype (WT), failing CaMKIIδC transgenic (TG) mouse, and failing human hearts. ATX-II (0.25-10 nmol/L) was used to enhance late INa. Spontaneous Ca loss from the SR during diastole (Ca sparks), DADs, non-triggered diastolic Ca transients in myocytes and premature beats of isometrically twitching papillary muscles were used as readouts for proarrhythmogenic events. CaMKII autophosphorylation was assessed by immunoblots. Late INa was inhibited using ranolazine (Ran, 10 µmol/L) or TTX (2 µmol/L), and CaMKII by KN-93 (1 µmol/L) or AIP (1 µmol/L). RESULTS: In WT myocytes, sub-nanomolar ATX-II exposure (0.5 nmol/L) enhanced late INa by ~60%, which resulted in increased diastolic SR Ca loss despite unaltered SR Ca content. In parallel, DADs and non-triggered diastolic Ca transients arose. Inhibition of enhanced late INa by RAN or TTX significantly attenuated diastolic SR Ca loss and suppressed DADs as well as mechanical alternans in mouse and diastolic SR Ca loss in failing human myocytes. ATX-II caused Ca-dependent CaMKII-activation without changes in protein expression, which was reversible by Ran or AIP. Conversely, CaMKII-inhibition decreased diastolic SR Ca loss, DADs and non-triggered diastolic Ca transients despite ATX-II-exposure. Finally, failing mouse myocytes with increased CaMKII activity (TG CaMKIIδC) showed an even aggravated diastolic SR Ca loss that was associated with an increased frequency of non-triggered diastolic Ca transients upon enhanced late INa. CONCLUSIONS: Increased late INa (in disease-comparable ranges) induces proarrhythmogenic events during diastole in healthy and failing mouse myocytes, which are mediated via CaMKII-dependent SR Ca loss. Inhibition of late INa not only attenuated these cellular arrhythmias in mouse myocytes but also in failing human myocytes indicating some antiarrhythmic potential for an inhibition of the elevated late INa/CaMKII signaling pathway in this setting.

Telethonin deficiency is associated with maladaptation to biomechanical stress in the mammalian heart.

RATIONALE: Telethonin (also known as titin-cap or t-cap) is a 19-kDa Z-disk protein with a unique ß-sheet structure, hypothesized to assemble in a palindromic way with the N-terminal portion of titin and to constitute a signalosome participating in the process of cardiomechanosensing. In addition, a variety of telethonin mutations are associated with the development of several different diseases; however, little is known about the underlying molecular mechanisms and telethonin's in vivo function. OBJECTIVE: Here we aim to investigate the role of telethonin in vivo and to identify molecular mechanisms underlying disease as a result of its mutation. METHODS AND RESULTS: By using a variety of different genetically altered animal models and biophysical experiments we show that contrary to previous views, telethonin is not an indispensable component of the titin-anchoring system, nor is deletion of the gene or cardiac specific overexpression associated with a spontaneous cardiac phenotype. Rather, additional titin-anchorage sites, such as actin-titin cross-links via α-actinin, are sufficient to maintain Z-disk stability despite the loss of telethonin. We demonstrate that a main novel function of telethonin is to modulate the turnover of the proapoptotic tumor suppressor p53 after biomechanical stress in the nuclear compartment, thus linking telethonin, a protein well known to be present at the Z-disk, directly to apoptosis ("mechanoptosis"). In addition, loss of telethonin mRNA and nuclear accumulation of this protein is associated with human heart failure, an effect that may contribute to enhanced rates of apoptosis found in these hearts. CONCLUSIONS: Telethonin knockout mice do not reveal defective heart development or heart function under basal conditions, but develop heart failure following biomechanical stress, owing at least in part to apoptosis of cardiomyocytes, an effect that may also play a role in human heart failure.

Impact of transcatheter edge-to-edge mitral valve repair on central sleep apnoea.

AIMS: Sleep-disordered breathing (SDB) and its subtype central sleep apnoea (CSA) are highly prevalent in patients with heart failure and associated with worse prognosis. Whereas pharmacological therapy of heart failure has been shown to ameliorate CSA, results from previous studies on the effect of mitral regurgitation therapy on SDB are contradicting. The aim of this study was to assess the impact of transcatheter edge-to-edge mitral valve repair (TEER) on prevalence and severity of CSA. METHODS AND RESULTS: We enrolled 47 patients undergoing TEER for symptomatic mitral regurgitation in a prospective study. Secondary mitral regurgitation and left ventricular ejection fraction < 50% were present in 79% and 68% of patients, respectively. Respiratory polygraphy was performed before TEER in a compensated condition and four weeks after the procedure. 34 patients completed the follow-up. At baseline, 19 (56%) patients showed moderate-to-severe SDB, of whom 13 (68%) were classified as CSA. Both apnoea-hypopnoea index and percentage of recorded time spent in Cheyne-Stokes respiration strongly decreased from baseline to follow-up (median [IQR] 16 [7-30] vs. 7 [4-15] /h, p = 0.007; 6 [0-34] vs. 0 [0-8] %, p = 0.008). Median relative reduction of central apnoea index was 75% (p = 0.023), while obstructive apnoea index did not change significantly. Increase in stroke volume after TEER and high systolic pulmonary artery pressure at baseline predicted a > 50% reduction of both Apnoea-hypopnoea index and Cheyne-Stokes respiration. CONCLUSION: TEER is associated with a significant short-term reduction of CSA and Cheyne-Stokes respiration in high-risk patients, strengthening its value as an effective treatment option for advanced heart failure.

Transapical mitral valve implantation for treatment of symptomatic mitral valve disease: a real-world multicentre experience.

AIMS: Transcatheter mitral valve implantation (TMVI) is a new treatment option for patients with symptomatic mitral valve (MV) disease. Real-world data have not yet been reported. This study aimed to assess procedural and 30-day outcomes of TMVI in a real-world patient cohort. METHOD AND RESULTS: All consecutive patients undergoing implantation of a transapically delivered self-expanding valve at 26 European centres from January 2020 to April 2021 were included in this retrospective observational registry. Among 108 surgical high-risk patients included (43% female, mean age 75 ± 7 years, mean STS-PROM 7.2 ± 5.3%), 25% was treated for an off-label indication (e.g. previous MV intervention or surgery, mitral stenosis, mitral annular calcification). Patients were highly symptomatic (New York Heart Association [NYHA] functional class III/IV in 86%) and mitral regurgitation (MR) was graded 3+/4+ in 95% (38% primary, 37% secondary, and 25% mixed aetiology). Technical success rate was 96%, and MR reduction to ≤1+ was achieved in all patients with successful implantation. There were two procedural deaths and 30-day all-cause mortality was 12%. At early clinical follow-up, MR reduction was sustained and there were significant reductions of pulmonary pressure (systolic pulmonary artery pressure 52 vs. 42 mmHg, p < 0.001), and tricuspid regurgitation severity (p = 0.013). Heart failure symptoms improved significantly (73% in NYHA class I/II, p < 0.001). Procedural success rate according to MVARC criteria was 80% and was not different in patients treated for an off-label indication (74% vs. 81% for off- vs. on-label, p = 0.41). CONCLUSION: In a real-world patient population, TMVI has a high technical and procedural success rate with efficient and durable MR reduction and symptomatic improvement.

Limitations of FKBP12.6-directed treatment strategies for maladaptive cardiac remodeling and heart failure.

Sarcoplasmic reticulum (SR) calcium (Ca) leak can be reduced by enhancing FKBP12.6 binding to SR Ca release channels (RyR2) and expression of a "sticky" FKBP12.6(D37S) mutant may correct reduced binding stoichiometry in RyR2 from failing hearts. Both calcium/calmodulin-dependent protein kinase IIδc (CaMKIIδc) and protein kinase A (PKA) are activated in heart failure and promote SR Ca leak at RyR2. It is possible that FKBP12.6 dissociation from RyR2 may promote remodeling and that interventions to reassociate FKBP12.6 with RyR2 reflect a future therapeutic strategy. We created transgenic (TG) mice expressing FKBP12.6(D37S) and tested their capacity to improve intracellular Ca handling and pathological remodeling in vivo. FKBP12.6(D37S) TG mice were cross-bred with CaMKIIδc TG mice, which are known to exhibit pronounced RyR2 dysfunction and heart failure. We observed a significant improvement of post-rest Ca transients and a higher SR Ca content in FKBP12.6(D37S) TG mice. In double-TG mice, a marked reduction of SR Ca spark frequency indicated reduced SR Ca leak but neither SR Ca transient amplitude, SR Ca content nor morphological or functional parameters improved in vivo. Likewise, FKBP12.6(D37S) TG mice subjected to increased afterload after aortic banding exhibited higher SR Ca load but did not exhibit any improvement in hypertrophic growth or functional decline. Enhancement of FKBP12.6-RyR2 binding markedly reduced RyR2 Ca leak in CaMKIIδc-induced heart failure and in pressure overload. Our data suggest that activation of CaMKIIδc and pressure overload confer significant resistance towards approaches aiming at FKBP12.6-RyR2 reconstitution in heart failure and maladaptive remodeling, although RyR2 Ca leak can be reduced.

Differential cardiac remodeling in preload versus afterload.

BACKGROUND: Hemodynamic load regulates myocardial function and gene expression. We tested the hypothesis that afterload and preload, despite similar average load, result in different phenotypes. METHODS AND RESULTS: Afterload and preload were compared in mice with transverse aortic constriction (TAC) and aortocaval shunt (shunt). Compared with sham mice, 6 hours after surgery, systolic wall stress (afterload) was increased in TAC mice (+40%; P<0.05), diastolic wall stress (preload) was increased in shunt (+277%; P<0.05) and TAC mice (+74%; P<0.05), and mean total wall stress was similarly increased in TAC (69%) and shunt mice (67%) (P=NS, TAC versus shunt; each P<0.05 versus sham). At 1 week, left ventricular weight/tibia length was significantly increased by 22% in TAC and 29% in shunt mice (P=NS, TAC versus shunt). After 24 hours and 1 week, calcium/calmodulin-dependent protein kinase II signaling was increased in TAC. This resulted in altered calcium cycling, including increased L-type calcium current, calcium transients, fractional sarcoplasmic reticulum calcium release, and calcium spark frequency. In shunt mice, Akt phosphorylation was increased. TAC was associated with inflammation, fibrosis, and cardiomyocyte apoptosis. The latter was significantly reduced in calcium/calmodulin-dependent protein kinase IIdelta-knockout TAC mice. A total of 157 mRNAs and 13 microRNAs were differentially regulated in TAC versus shunt mice. After 8 weeks, fractional shortening was lower and mortality was higher in TAC versus shunt mice. CONCLUSIONS: Afterload results in maladaptive fibrotic hypertrophy with calcium/calmodulin-dependent protein kinase II-dependent altered calcium cycling and apoptosis. Preload is associated with Akt activation without fibrosis, little apoptosis, better function, and lower mortality. This indicates that different loads result in distinct phenotype differences that may require specific pharmacological interventions.

Acquired von Willebrand syndrome and factor VIII in patients with moderate to severe mitral regurgitation undergoing transcatheter mitral valve repair.

BACKGROUND AND HYPOTHESIS: The acquired von Willebrand syndrome (AvWS), which predisposes to bleeding events, is often related to valvular heart diseases. We investigated possible implications of AvWS and factor VIII levels in patients with moderate to severe mitral regurgitation (MR) undergoing transcatheter mitral valve repair (TMVR). METHODS AND RESULTS: 123 patients with moderate to severe MR were prospectively enrolled. Complete measurements of von Willebrand Factor activity (vWFAct), von Willebrand Factor antigen (vWFAg), and factor VIII expression before and 4 weeks after TMVR were available in 85 patients. At baseline, seven patients had a history of gastrointestinal bleeding, two patients suffered bleeding events during their hospital stay, and one patient had a bleeding 4 weeks after TMVR. Even though vWFAct, vWFAct/vWFAg ratio and vWFAg values did not change after TMVR, we observed a significantly lower vWFAct/vWFAg ratio in patients with primary MR as compared to patients with secondary MR both at baseline (p = 0.022) and 4 weeks following the TMVR procedure (p = 0.003). Additionally, patients with a mean mitral valve gradient ≥4 mmHg after TMVR had significantly lower vWFAct/vWFAg ratios as compared to patients with a mean mitral valve gradient <4 mmHg (p = 0.001). CONCLUSIONS: MR of primary etiology was associated with lower vWFAct/vWFAg ratio, hinting toward HMWM loss due to shear stress caused by eccentric regurgitation jets. In addition, morphological changes leading to postprocedural transmitral gradients ≥4 mmHg were related to lower vWFAct/vWFAg ratio 4 weeks after the procedure. Alterations of the vWFAct/vWFAg ratio in turn did not translate into a greater risk for bleeding events.

BNP controls early load-dependent regulation of SERCA through calcineurin.

Heart failure is characterised by reduced expression of sarcoplasmic reticulum calcium-ATPase (SERCA) and increased expression of B-type natriuretic peptide (BNP). The present study was performed to investigate causality of this inverse relationship under in vivo conditions in the transversal aortic constriction mouse model (TAC). Left ventricular SERCA-mRNA expression was significantly upregulated in TAC by 32% after 6 h, but not different from sham after 24 h. Serum proANP and BNP levels were increased in TAC after 24 h (BNP +274%, p < 0.01; proANP +60%, p < 0.05), but only proANP levels were increased after 6 h (+182%, p < 0.01). cGMP levels were only increased 24 h after TAC (+307%, p < 0.01), but not 6 h after TAC. BNP infusion inhibited the increase in SERCA expression 6 h after TAC. In BNP-receptor-knockout animals (GC-A), the expression of SERCA was still significantly increased 24 h after TAC at the mRNA level by 35% (p < 0.05), as well as at the protein level by 25% (p < 0.05). MCIP expression as an indicator of calcineurin activity was regulated in parallel to SERCA after 6 and 24 h. MCIP-mRNA was increased by 333% 6 h after TAC, but not significantly different from sham after 24 h. In the GC-A-KO mice, MCIP-mRNA was significantly increased in TAC compared to WT after 24 h. In mice with BNP infusion, MCIP was significantly lower 6 h after TAC compared to control animals. In conclusion, mechanical load leads to an upregulation of SERCA expression. This is followed by upregulation of natriuretic peptides with subsequent suppression of SERCA upregulation. Elevated natriuretic peptides may suppress SERCA expression by inhibition of calcineurin activity via activation of GC-A.

Control of p21Cip by BRCA1-associated protein is critical for cardiomyocyte cell cycle progression and survival.

AIMS: Identifying the key components in cardiomyocyte cell cycle regulation is of relevance for the understanding of cardiac development and adaptive and maladaptive processes in the adult myocardium. BRCA1-associated protein (BRAP) has been suggested as a cytoplasmic retention factor for several proteins including Cyclin-dependent-kinase inhibitor p21Cip. We observed profound expressional changes of BRAP in early postnatal myocardium and investigated the impact of BRAP on cardiomyocyte cell cycle regulation. METHODS AND RESULTS: General knockout of Brap in mice evoked embryonic lethality associated with reduced myocardial wall thickness and lethal cardiac congestion suggesting a prominent role for BRAP in cardiomyocyte proliferation. αMHC-Cre driven cardiomyocyte-specific knockout of Brap also evoked lethal cardiac failure shortly after birth. Likewise, conditional cardiomyocyte-specific Brap deletion using tamoxifen-induced knockout in adult mice resulted in marked ventricular dilatation and heart failure 3 weeks after induction. Several lines of evidence suggest that Brap deletion evoked marked inhibition of DNA synthesis and cell cycle progression. In cardiomyocytes with proliferative capacity, this causes developmental arrest, whereas in adult hearts loss of BRAP-induced apoptosis. This is explained by altered signalling through p21Cip which we identify as the link between BRAP and cell cycle/apoptosis. BRAP deletion enhanced p21Cip expression, while BRAP overexpression in cardiomyocyte-specific transgenic mice impeded p21Cip expression. That was paralleled by enhanced nuclear Ki-67 expression and DNA synthesis. CONCLUSION: By controlling p21Cip activity BRAP expression controls cell cycle activity and prevents developmental arrest in developing cardiomyocytes and apoptosis in adult cardiomyocytes.

The role of diabetes in cardiomyopathies of different etiologies-Characteristics and 1-year follow-up results of the EVITA-HF registry.

BACKGROUND: Type 2 diabetes is a major risk factor for cardiovascular diseases, e.g. coronary artery disease (CAD). But it has also been shown that diabetes can cause heart failure independently of ischemic heart disease (IHD) by causing diabetic cardiomyopathy. In contrast to diabetes and IHD, limited data exist regarding patients with diabetes and dilated cardiomyopathy (DCM). METHODS: EVIdence based TreAtment in Heart Failure (EVITA-HF) comprises web-based case report data on demography, diagnostic measures, adverse events and 1-year follow-up of patients hospitalized for chronic heart failure and an ejection fraction ≤40%. In the present study we focused on the results of patients with diabetes and heart failure. RESULTS: Between February 2009 and November 2015, 4101 patients with chronic heart failure were included in 16 tertiary care centers in Germany. The mortality in patients with diabetes and DCM (n = 323) was more than double (15.2%) than that of DCM patients without diabetes (6.5%, p<0.001, n = 885). In contrast the mortality rate of patients with IHD was not influenced by the presence of diabetes (17.6% in patients with IHD and diabetes n = 945, vs. 14.7% in patients with IHD and no diabetes, n = 1236, p = 0.061). The results also remained stable after performing a multivariable analysis (unadjusted p-value for interaction = 0.002, adjusted p = 0.046). CONCLUSION: The influence of diabetes on the mortality rate is only significant in patients with DCM not in patients with CAD. Therefore, the underlying mechanisms of this effect should be studied in greater detail to improve patient care and outcome.

Predictors of functional improvement in the short term after MitraClip implantation in patients with secondary mitral regurgitation.

BACKGROUND AND OBJECTIVES: MitraClip implantation is an established therapy for secondary mitral regurgitation (MR) in high-risk patients and has shown to improve several important outcome parameters such as functional capacity. Patient selection is both challenging and crucial for achieving therapeutic success. This study investigated baseline predictors of functional improvement as it was quantified by the six-minute walk distance (6MWD) after transcatheter mitral valve repair. METHODS AND RESULTS: We retrospectively analyzed 79 patients with secondary MR treated with MitraClip implantation at an academic tertiary care center. Before and four weeks after the procedure, all patients underwent comprehensive clinical assessment, six-minute walk tests and echocardiography. 6MWD significantly improved after MitraClip therapy (295 m vs. 265 m, p < 0.001). A linear regression model including seven clinical baseline variables significantly predicted the change in 6MWD (p = 0.002, R2 = 0.387). Female gender, diabetes mellitus and arterial hypertension were found to be significant negative predictors of 6MWD improvement. At baseline, female patients had significant higher left ventricular ejection fraction (49% vs. 42%, p = 0.019) and lower 6MWD (240 m vs. 288 m, p = 0.034) than male patients. CONCLUSION: MitraClip implantation in secondary MR significantly improves functional capacity in high-risk patients even in the short term of four weeks after the procedure. Female gender, diabetes mellitus and arterial hypertension are baseline predictors of a less favourable functional outcome. While further validation in a larger cohort is recommended, these parameters may improve patient selection for MitraClip therapy.

Exercise intolerance and systemic manifestations of pulmonary emphysema in a mouse model.

BACKGROUND: Systemic effects of chronic obstructive pulmonary disease (COPD) significantly contribute to severity and mortality of the disease. We aimed to develop a COPD/emphysema model exhibiting systemic manifestations of the disease. METHODS: Female NMRI mice were treated 5 times intratracheally with porcine pancreatic elastase (emphysema) or phosphate-buffered saline (control). Emphysema severity was quantified histologically by mean linear intercept, exercise tolerance by treadmill running distance, diaphragm dysfunction using isolated muscle strips, pulmonary hypertension by measuring right ventricular pressure, and neurohumoral activation by determining urinary norepinephrine concentration. RESULTS: Mean linear intercept was higher in emphysema (260.7 +/- 26.8 microm) than in control lungs (24.7 +/- 1.7 microm). Emphysema mice lost body weight, controls gained weight. Running distance was shorter in emphysema than in controls. Diaphragm muscle length was shorter in controls compared to emphysema. Fatigue tests of muscle strips revealed impaired relaxation in emphysema diaphragms. Maximum right ventricular pressure and norepinephrine were elevated in emphysema compared to controls. Linear correlations were observed between running distance changes and intercept, right ventricular weight, norepinephrine, and diaphragm length. CONCLUSION: The elastase mouse model exhibited severe emphysema with consecutive exercise limitation, and neurohumoral activation. The model may deepen our understanding of systemic aspects of COPD.

Generation of functional cardiomyocytes from adult mouse spermatogonial stem cells.

Stem cell-based therapy is a promising approach for the treatment of heart failure. Adult stem cells with the pluripotency of embryonic stem cells (ESCs) would be an ideal cell source. Recently, we reported the successful establishment of multipotent adult germline stem cells (maGSCs) from mouse testis. These cultured maGSCs show phenotypic characteristics similar to ESCs and can spontaneously differentiate into cells from all 3 germ layers. In the present study, we used the hanging drop method to differentiate maGSCs into cardiomyocytes and analyzed their functional properties. Differentiation efficiency of beating cardiomyocytes from maGSCs was similar to that from ESCs. The maGSC-derived cardiomyocytes expressed cardiac-specific L-type Ca(2+) channels and responded to Ca(2+) channel-modulating drugs. Cx43 was expressed at cell-to-cell contacts in cardiac clusters, and fluorescence recovery after photobleaching assay showed the presence of functional gap junctions among cardiomyocytes. Action potential analyses demonstrated the presence of pacemaker-, ventricle-, atrial-, and Purkinje-like cardiomyocytes. Stimulation with isoproterenol resulted in a significant increase in beating frequency, whereas the addition of cadmium chloride abolished spontaneous electrical activity. Confocal microscopy analysis of intracellular Ca(2+) in maGSC-derived cardiomyocytes showed that calcium increased periodically throughout the cell in a homogenous fashion, pointing to a fine regulated Ca(2+) release from intracellular Ca(2+) stores. By using line-scan mode, we found rhythmic Ca(2+) transients. Furthermore, we transplanted maGSCs into normal hearts of mice and found that maGSCs were able to proliferate and differentiate. No tumor formation was found up to 1 month after cell transplantation. Taken together, we believe that maGSCs provide a new source of distinct types of cardiomyocytes for basic research and potential therapeutic application.

A machine learning approach for the prediction of pulmonary hypertension.

BACKGROUND: Machine learning (ML) is a powerful tool for identifying and structuring several informative variables for predictive tasks. Here, we investigated how ML algorithms may assist in echocardiographic pulmonary hypertension (PH) prediction, where current guidelines recommend integrating several echocardiographic parameters. METHODS: In our database of 90 patients with invasively determined pulmonary artery pressure (PAP) with corresponding echocardiographic estimations of PAP obtained within 24 hours, we trained and applied five ML algorithms (random forest of classification trees, random forest of regression trees, lasso penalized logistic regression, boosted classification trees, support vector machines) using a 10 times 3-fold cross-validation (CV) scheme. RESULTS: ML algorithms achieved high prediction accuracies: support vector machines (AUC 0.83; 95% CI 0.73-0.93), boosted classification trees (AUC 0.80; 95% CI 0.68-0.92), lasso penalized logistic regression (AUC 0.78; 95% CI 0.67-0.89), random forest of classification trees (AUC 0.85; 95% CI 0.75-0.95), random forest of regression trees (AUC 0.87; 95% CI 0.78-0.96). In contrast to the best of several conventional formulae (by Aduen et al.), this ML algorithm is based on several echocardiographic signs and feature selection, with estimated right atrial pressure (RAP) being of minor importance. CONCLUSIONS: Using ML, we were able to predict pulmonary hypertension based on a broader set of echocardiographic data with little reliance on estimated RAP compared to an existing formula with non-inferior performance. With the conceptual advantages of a broader and unbiased selection and weighting of data our ML approach is suited for high level assistance in PH prediction.