Early and Late Results after Surgical Mitral Valve Repair: A High-Volume Center Experience.

BACKGROUND: Surgical mitral valve repair is the gold standard treatment of severe primary mitral regurgitation (MR). In the light of rapidly evolving percutaneous technologies, current surgical outcome data are essential to support heart-team-based decision-making. METHODS: This retrospective, high-volume, single-center study analyzed in 1779 patients with primary MR early morbidity and mortality, postoperative valve function, and long-term survival after mitral valve (MV) repair. Surgeries were performed between 2009 and 2022. Surgical approaches included full sternotomy (FS) and right-sided minithoracotomy (minimally invasive cardiac [MIC] surgery). RESULTS: Of the surgeries (mean age: 59.9 [standard deviation:11.4] years; 71.5% males), 85.6% (n = 1,527) were minithoracotomies. Concomitant procedures were performed in 849 patients (47.7%), including tricuspid valve and/or atrial septal defect repair, cryoablation, and atrial appendage closure. The majority of patients did not need erythrocyte concentrates. Mediastinitis and rethoracotomy for bleeding rates were 0.1 and 4.3%, respectively. Reoperation before discharge for failed repair was necessary in 12 patients (0.7%). Freedom from more than moderate MR was > 99%. Thirty-day mortality was 0.2% and did not differ significantly between groups (p = 0.37). Median follow-up was 48.2 months with a completeness of 95.9%. Long-term survival was similar between groups (p = 0.21). In the FS and MIC groups, 1-, 5-, and 10-year survival rates were 98.8 and 98.8%, 92.9 and 94.4%, and 87.4 and 83.1%, respectively. CONCLUSION: MV surgery, both minimally invasive and via sternotomy, is associated with high repair rates, excellent perioperative outcomes, and long-term survival. Data underscore the effectiveness of surgical repair in managing MR, even in the era of advancing interventional techniques.

High Efficacy and Low Early Mortality in High-Volume Center Tricuspid Valve Surgery.

BACKGROUND: Isolated tricuspid valve surgery has been associated with early mortality rates of up to 10%. With rapidly emerging interventional catheter-based options, the question arises whether current technical and perioperative protocols in cardiac surgery translate into lower than previously expected mortality rates, especially when looking at data from high-volume centers. METHODS: We performed a retrospective single-center analysis in 369 patients undergoing isolated tricuspid valve repair (n = 256) or replacement (n = 113) between 2009 and 2021. Surgical approaches included full sternotomy, as well as right-sided minithoracotomy. According to a recently introduced clinical risk score, patients were divided into scoring groups, and observed (O) versus expected (E) early mortality were compared. Pre- and postoperative tricuspid valve function was also analyzed. RESULTS: Overall, 30-day mortality was 4.1%, ranging from 0% (scoring group 0-1 points) to 8.7% (scoring group ≥ 10 points), which was substantially lower than the expected early mortality (2% in the lowest to 34% in the highest scoring group). Preoperative tricuspid regurgitation was severe in 71.3% (n = 263), moderate to severe in 14.9% (n = 55), and mild or less in 6.5% (n = 24). The corresponding postoperative values were 0% (n = 0), 1.4% (n = 5), and 81.6% (n = 301). CONCLUSION: Our high-volume center data indicate substantially lower than predicted 30-day mortality in different cardiac surgical risk scoring groups. The majority of patients had zero to minimal residual tricuspid valve insufficiency postoperatively. Randomized controlled trials are needed to compare tricuspid valve functional results and long-term outcomes of surgical versus interventional procedures in patients undergoing isolated tricuspid valve procedures.

High-sensitivity cardiac troponin I after coronary artery bypass grafting for post-operative decision-making.

AIMS: Current troponin cut-offs suggested for the post-operative workup of patients following coronary artery bypass graft (CABG) surgery are based on studies using non-high-sensitive troponin assays or are arbitrarily chosen. We aimed to identify an optimal cut-off and timing for a proprietary high-sensitivity cardiac troponin I (hs-cTnI) assay to facilitate post-operative clinical decision-making. METHODS AND RESULTS: We performed a retrospective analysis of all patients undergoing elective isolated CABG at our centre between January 2013 and May 2019. Of 4684 consecutive patients, 161 patients (3.48%) underwent invasive coronary angiography after surgery, of whom 86 patients (53.4%) underwent repeat revascularization. We found an optimal cut-off value for peak hs-cTnI of >13 000 ng/L [>500× the upper reference limit (URL)] to be significantly associated with repeat revascularization within 48 h after surgery, which was internally validated through random repeated sampling with 1000 iterations. The same cut-off also predicted 30-day major adverse cardiovascular events and all-cause mortality after a median follow-up of 3.1 years, which was validated in an external cohort. A decision tree analysis of serial hs-cTnI measurements showed no added benefit of hs-cTnI measurements in patients with electrocardiographic or echocardiographic abnormalities or haemodynamic instability. Likewise, early post-operative hs-cTnI elevations had a low yield for clinical decision-making and only later elevations (at 12-16 h post-operatively) using a threshold of 8000 ng/L (307× URL) were significantly associated with repeat revascularization with an area under the curve of 0.92 (95% confidence interval 0.88-0.95). CONCLUSION: Our data suggest that for hs-cTnI, higher cut-offs than currently recommended should be used in the post-operative management of patients following CABG.

Long-Term Clinical Outcome in Elderly Patients Undergoing Mitral Valve Repair.

BACKGROUND: Long-term data on patients over 75 years undergoing mitral valve (MV) repair are scarce. At our high-volume institution, we, therefore, aimed to evaluate mortality, stroke risk, and reoperation rates in these patients. METHODS: We investigated clinical outcomes in 372 patients undergoing MV repair with (n = 115) or without (n = 257) tricuspid valve repair. The primary endpoint was the probability of survival up to a maximum follow-up of 9 years. Secondary clinical endpoints were stroke and reoperation of the MV during follow-up. Univariate and multivariable Cox regression analysis was performed to assess independent predictors of mortality. Mortality was also compared with the age- and sex-adjusted general population. RESULTS: During a median follow-up period of 37 months (range: 0.1-108 months), 90 patients died. The following parameters were independently associated with mortality: double valve repair (hazard ratio, confidence interval [HR, 95% CI]: 2.15, 1.37-3.36), advanced age (HR: 1.07, CI: 1.01-1.14 per year), diabetes (HR: 1.97, CI: 1.13-3.43), preoperative New York Heart Association (NYHA) functional class (HR: 1.41, CI: 1.01-1.97 per class), and operative creatininemax levels (HR: 1.32, CI: 1.13-1.55 per mg/dL). The risk of stroke in the isolated MV and double valve repair groups at postoperative year 5 was 5.0 and 4.1%, respectively (p = 0.65). The corresponding values for the risk of reoperation were 4.0 and 7.0%, respectively (p = 0.36). Nine-year survival was comparable with the general population (53.2 vs. 53.1%). CONCLUSION: Various independent risk factors for mortality in elderly MV repair patients could be identified, but overall survival rates were similar to those of the general population. Consequently, our data indicates that repairing the MV in elderly patients represents a suitable and safe surgical approach.

Prognostic Factors for Long-Term Survival after Surgical Resection of Primary Cardiac Sarcoma.

BACKGROUND: Primary cardiac sarcoma (CS) is an extremely rare disease. This study aims to identify possible prognostic factors for long-term survival. METHODS: A total of 17 consecutive patients who were treated for primary CS between 2003 und 2018 at two cardiac centers were investigated. Clinical data and histological characteristics of the tumors were analyzed. Long-term follow-up of all patients were performed. RESULTS: The median age was 54 years (range: 23-74). The tumors originated from the left side of the heart in nine patients. Histologically, there were four angiosarcomas, three intimal sarcomas, and three synovial sarcomas. One- and 7-year survivals were 81.9 and 18.2%, respectively. Low expression levels of Ki-67 tended to be associated with increased survival (log-rank p = 0.06). Adjuvant chemotherapy but not radiotherapy regardless of existing metastases was associated with significantly increased survival (log-rank p = 0.001). CONCLUSION: Angiosarcoma was the most common type of CS. The survival of CS patients is poor but prognostic factors, such as Ki-67, may help estimate the course of the disease. Survival could be improved significantly with chemotherapy.

Iron-regulatory proteins secure iron availability in cardiomyocytes to prevent heart failure.

Aims: Iron deficiency (ID) is associated with adverse outcomes in heart failure (HF) but the underlying mechanisms are incompletely understood. Intracellular iron availability is secured by two mRNA-binding iron-regulatory proteins (IRPs), IRP1 and IRP2. We generated mice with a cardiomyocyte-targeted deletion of Irp1 and Irp2 to explore the functional implications of ID in the heart independent of systemic ID and anaemia. Methods and results: Iron content in cardiomyocytes was reduced in Irp-targeted mice. The animals were not anaemic and did not show a phenotype under baseline conditions. Irp-targeted mice, however, were unable to increase left ventricular (LV) systolic function in response to an acute dobutamine challenge. After myocardial infarction, Irp-targeted mice developed more severe LV dysfunction with increased HF mortality. Mechanistically, the activity of the iron-sulphur cluster-containing complex I of the mitochondrial electron transport chain was reduced in left ventricles from Irp-targeted mice. As demonstrated by extracellular flux analysis in vitro, mitochondrial respiration was preserved at baseline but failed to increase in response to dobutamine in Irp-targeted cardiomyocytes. As shown by 31P-magnetic resonance spectroscopy in vivo, LV phosphocreatine/ATP ratio declined during dobutamine stress in Irp-targeted mice but remained stable in control mice. Intravenous injection of ferric carboxymaltose replenished cardiac iron stores, restored mitochondrial respiratory capacity and inotropic reserve, and attenuated adverse remodelling after myocardial infarction in Irp-targeted mice but not in control mice. As shown by electrophoretic mobility shift assays, IRP activity was significantly reduced in LV tissue samples from patients with advanced HF and reduced LV tissue iron content. Conclusions: ID in cardiomyocytes impairs mitochondrial respiration and adaptation to acute and chronic increases in workload. Iron supplementation restores cardiac energy reserve and function in iron-deficient hearts.

The combined effects of ranolazine and dronedarone on human atrial and ventricular electrophysiology.

INTRODUCTION: Pharmacological rhythm control of atrial fibrillation (AF) in patients with structural heart disease is limited. Ranolazine in combination with low dose dronedarone remarkably reduced AF-burden in the phase II HARMONY trial. We thus aimed to investigate the possible mechanisms underlying these results. METHODS AND RESULTS: Patch clamp experiments revealed that ranolazine (5µM), low-dose dronedarone (0.3µM), and the combination significantly prolonged action potential duration (APD90) in atrial myocytes from patients in sinus rhythm (prolongation by 23.5±0.1%, 31.7±0.1% and 25.6±0.1% respectively). Most importantly, in atrial myocytes from patients with AF ranolazine alone, but more the combination with dronedarone, also prolonged the typically abbreviated APD90 (prolongation by 21.6±0.1% and 31.9±0.1% respectively). It was clearly observed that neither ranolazine, dronedarone nor the combination significantly changed the APD or contractility and twitch force in ventricular myocytes or trabeculae from patients with heart failure (HF). Interestingly ranolazine, and more so the combination, but not dronedarone alone, caused hyperpolarization of the resting membrane potential in cardiomyocytes from AF. As measured by confocal microscopy (Fluo-3), ranolazine, dronedarone and the combination significantly suppressed diastolic sarcoplasmic reticulum (SR) Ca(2+) leak in myocytes from sinus rhythm (reduction by ranolazine: 89.0±30.7%, dronedarone: 75.6±27.4% and combination: 78.0±27.2%), in myocytes from AF (reduction by ranolazine: 67.6±33.7%, dronedarone: 86.5±31.7% and combination: 81.0±33.3%), as well as in myocytes from HF (reduction by ranolazine: 64.8±26.5% and dronedarone: 65.9±29.3%). CONCLUSIONS: Electrophysiological measurements during exposure to ranolazine alone or in combination with low-dose dronedarone showed APD prolongation, cellular hyperpolarization and reduced SR Ca(2+) leak in human atrial myocytes. The combined inhibitory effects on various currents, in particular Na(+) and K(+) currents, may explain the anti-AF effects observed in the HARMONY trial. Therefore, the combination of ranolazine and dronedarone, but also ranolazine alone, may be promising new treatment options for AF, especially in patients with HF, and merit further clinical investigation.

Sex-dependent alterations of Ca2+ cycling in human cardiac hypertrophy and heart failure.

AIMS: Clinical studies have shown differences in the propensity for malignant ventricular arrhythmias between women and men suffering from cardiomyopathies and heart failure (HF). This is clinically relevant as it impacts therapies like prophylactic implantable cardioverter-defibrillator implantation but the pathomechanisms are unknown. As an increased sarcoplasmic reticulum (SR) Ca(2+) leak is arrhythmogenic, it could represent a cellular basis for this paradox. METHODS/RESULTS: We evaluated the SR Ca(2+) leak with respect to sex differences in (i) afterload-induced cardiac hypertrophy (Hy) with preserved left ventricular (LV) function and (ii) end-stage HF. Cardiac function did not differ between sexes in both cardiac pathologies. Human cardiomyocytes isolated from female patients with Hy showed a significantly lower Ca(2+) spark frequency (CaSpF, confocal microscopy, Fluo3-AM) compared with men (P < 0.05). As Ca(2+) spark width and duration were similar in women and men, this difference in CaSpF did not yet translate into a significant difference of the calculated SR Ca(2+) leak between both sexes at this stage of disease (P = 0.14). Epifluorescence measurements (Fura2-AM) revealed comparable Ca(2+) cycling properties (diastolic Ca(2+) levels, amplitude of systolic Ca(2+) transients, SR Ca(2+) load) in patients of both sexes suffering from Hy. Additionally, the increased diastolic CaSpF in male patients with Hy did not yet translate into an elevated ratio of cells showing arrhythmic events (Ca(2+) waves, spontaneous Ca(2+) transients) (P = 0.77). In the transition to HF, both sexes showed an increase of the CaSpF (P < 0.05) and the sex dependence was even more pronounced. Female patients had a 69 ± 10% lower SR Ca(2+) leak (P < 0.05), which now even translated into a lower ratio of arrhythmic cells in female HF patients compared with men (P < 0.001). CONCLUSION: These data show that the SR Ca(2+) leak is lower in women than in men with comparable cardiac impairment. Since the SR Ca(2+) leak triggers delayed afterdepolarizations, our findings may explain why women are less prone to ventricular arrhythmias and confirm the rationale of therapeutic measures reducing the SR Ca(2+) leak.

Inhibition of CaMKII Attenuates Progressing Disruption of Ca(2+) Homeostasis Upon Left Ventricular Assist Device Implantation in Human Heart Failure.

In heart failure, left ventricular assist device (LVAD) implantation is performed to ensure sufficient cardiac output. Whereas some patients are subsequently weaned from LVAD support, other patients still need heart transplantation. To elucidate underlying mechanisms, we assessed the arrhythmogenic SR-Ca(2+) leak at the time of LVAD implantation (HF-Im) and heart transplantation (HF-Tx) and evaluated the effects of CaMKII-inhibition. Human left-ventricular cardiomyocytes were isolated, paced at 1 Hz for 10 beats to ensure SR-Ca(2+) loading and scanned for diastolic Ca(2+) sparks (confocal microscopy). In HF-Im, the high diastolic spark frequency (CaSpF) of 0.76 ± 0.12 × 100 µm(-1) × s(-1) could be reduced to 0.48 ± 0.10 × 100 µm(-1) × s(-1) by CaMKII inhibition (AIP, 1 µM). The amplitude of Ca(2+) sparks, width, and length was not significantly altered. In sum, CaMKII inhibition yielded a clear tendency toward a reduction of the SR-Ca(2+) leak (n cells/patients = 76/6 vs. 108/6, P = 0.08). In HF-Tx, we detected an even higher CaSpF of 1.00 ± 0.10 100 µm(-1) × s(-1) and a higher SR-Ca(2+) leak compared with HF-Im (increase by 81 ± 33%, n cells/patients = 156/7 vs. 130/7, P < 0.05), which fits to the further decreased LV function. Here, CaMKII inhibition likewise reduced CaSpF (0.35 ± 0.09 100 µm(-1) × s(-1,) P = 0.06) and significantly reduced spark duration (n sparks/patients = 58/3 vs. 159/3, P < 0.05). Conclusively, the SR-Ca(2+) leak was reduced by 69 ± 12% in HF-Tx upon CaMKII inhibition (n cells/patients = 53/3 vs. 91/3, P < 0.05). These data show that the SR-Ca(2+) leak correlates with the development of LV function after LVAD implantation and may represent an important pathomechanism. The fact that CaMKII inhibition reduces the SR-Ca(2+) leak in HF-Tx suggests that CaMKII inhibition may be a promising option to beneficially influence clinical course after LVAD implantation.

Counteracting negative venous line pressures to avoid arterial air bubbles: an experimental study comparing two different types of miniaturized extracorporeal perfusion systems.

BACKGROUND: Because of its low rate of clinical complications, miniaturized extracorporeal perfusion systems (MEPS) are frequently used in heart centers worldwide. However, many recent studies refer to the higher probability of gaseous microemboli formation by MEPS, caused by subzero pressure values. This is the main reason why various de-airing devices were developed for today's perfusion systems. In the present study, we investigated the potential benefits of a simple one-way-valve connected to a volume replacement reservoir (OVR) for volume and pressure compensation. METHODS: In an experimental study on 26 pigs, we compared MEPS (n = 13) with MEPS plus OVR (n = 13). Except OVR, perfusion equipment was identical in both groups. Primary endpoints were pressure values in the venous line and the right atrium as well as the number and volume of air bubbles. Secondary endpoints were biochemical parameters of systemic inflammatory response, ischemia, hemodilution and hemolysis. RESULTS: One animal was lost in the MEPS + OVR group. In the MEPS + OVR group no pressure values below -150 mmHg in the venous line and no values under -100 mmHg in right atrium were noticed. On the contrary, nearly 20% of venous pressure values in the MEPS group were below -150 and approximately 10% of right atrial pressure values were below -100 mmHg. Compared with the MEPS group, the bubble counter device showed lower numbers of arterial air bubbles in the MEPS + OVR group (mean ± SD: 13444 ± 5709 vs. 1 ± 2, respectively; p < 0.001). In addition, bubble volume was significantly lower in the MEPS + OVR group than in the MEPS group (mean ± SD: 1522 ± 654 µl vs. 4 ± 6 µl, respectively; p < 0.001). The proinflammatory cytokine interleukin-6 and biochemical indices of cardiac ischemia (creatine kinase, and troponin I) were comparable between both groups. CONCLUSIONS: The use of a miniaturized perfusion system with a volume replacement reservoir is able to counteract excessive negative venous line pressures and to reduce the number and volume of arterial air bubbles. This approach may lead to a lower rate of neurological complications.

Ca2+/calmodulin-dependent protein kinase II and protein kinase A differentially regulate sarcoplasmic reticulum Ca2+ leak in human cardiac pathology.

BACKGROUND: Sarcoplasmic reticulum (SR) Ca(2+) leak through ryanodine receptor type 2 (RyR2) dysfunction is of major pathophysiological relevance in human heart failure (HF); however, mechanisms underlying progressive RyR2 dysregulation from cardiac hypertrophy to HF are still controversial. METHODS AND RESULTS: We investigated healthy control myocardium (n=5) and myocardium from patients with compensated hypertrophy (n=25) and HF (n=32). In hypertrophy, Ca(2+)/calmodulin-dependent protein kinase II (CaMKII) and protein kinase A (PKA) both phosphorylated RyR2 at levels that were not different from healthy myocardium. Accordingly, inhibitors of these kinases reduced the SR Ca(2+) leak. In HF, however, the SR Ca(2+) leak was nearly doubled compared with hypertrophy, which led to reduced systolic Ca(2+) transients, a depletion of SR Ca(2+) storage and elevated diastolic Ca(2+) levels. This was accompanied by a significantly increased CaMKII-dependent phosphorylation of RyR2. In contrast, PKA-dependent RyR2 phosphorylation was not increased in HF and was independent of previous ß-blocker treatment. In HF, CaMKII inhibition but not inhibition of PKA yielded a reduction of the SR Ca(2+) leak. Moreover, PKA inhibition further reduced SR Ca(2+) load and systolic Ca(2+) transients. CONCLUSIONS: In human hypertrophy, both CaMKII and PKA functionally regulate RyR2 and may induce SR Ca(2+) leak. In the transition from hypertrophy to HF, the diastolic Ca(2+) leak increases and disturbed Ca(2+) cycling occurs. This is associated with an increase in CaMKII- but not PKA-dependent RyR2 phosphorylation. CaMKII inhibition may thus reflect a promising therapeutic target for the treatment of arrhythmias and contractile dysfunction.

Early and late outcomes after minimally invasive direct coronary artery bypass vs. full sternotomy off-pump coronary artery bypass grafting.

Objectives: Minimally-invasive direct coronary artery bypass (MIDCAB) is a less-invasive alternative to full sternotomy off-pump coronary artery bypass (FS-OPCAB) revascularization of the left anterior descending artery (LAD). Some studies suggested that MIDCAB is associated with a greater risk of graft occlusion and repeat revascularization than FS-OPCAB LIMA-to-LAD grafting. Data comparing MIDCAB to FS-OPCAB with regard to long-term follow-up is scarce. We compared short- and long-term results of MIDCAB vs. FS-OPCAB revascularization over a maximum follow-up period of 10 years. Patients and methods: From December 2009 to June 2020, 388 elective patients were included in our retrospective study. 229 underwent MIDCAB, and 159 underwent FS-OPCAB LIMA-to-LAD grafting. Inverse probability of treatment weighting (IPTW) was used to adjust for selection bias and to estimate treatment effects on short- and long-term outcomes. IPTW-adjusted Kaplan-Meier estimates by study group were calculated for all-cause mortality, stroke, the risk of repeat revascularization and myocardial infarction up to a maximum follow-up of 10 years. Results: MIDCAB patients had less rethoracotomies (n = 13/3.6% vs. n = 30/8.0%, p = 0.012), fewer transfusions (0.93 units ± 1.83 vs. 1.61 units ± 2.52, p < 0.001), shorter mechanical ventilation time (7.6 ± 4.7 h vs. 12.1 ± 26.4 h, p = 0.005), and needed less hemofiltration (n = 0/0% vs. n = 8/2.4%, p = 0.004). Thirty-day mortality did not differ significantly between the two groups (n = 0/0% vs. n = 3/0.8%, p = 0.25). Long-term outcomes did not differ significantly between study groups. In the FS-OPCAB group, the probability of survival at 1, 5, and 10 years was 98.4%, 87.8%, and 71.7%, respectively. In the MIDCAB group, the corresponding values were 98.4%, 87.7%, and 68.7%, respectively (RR1.24, CI0.87-1.86, p = 0.7). In the FS group, the freedom from stroke at 1, 5, and 10 years was 97.0%, 93.0%, and 93.0%, respectively. In the MIDCAB group, the corresponding values were 98.5%, 96.9%, and 94.3%, respectively (RR0.52, CI0.25-1.09, p = 0.06). Freedom from repeat revascularization at 1, 5, and 10 years in the FS-OPCAB group was 92.2%, 84.7%, and 79.5%, respectively. In the MIDCAB group, the corresponding values were 94.8%, 90.2%, and 81.7%, respectively (RR0.73, CI0.47-1.16, p = 0.22). Conclusion: MIDCAB is a safe and efficacious technique and offers comparable long-term results regarding mortality, stroke, repeat revascularization, and freedom from myocardial infarction when compared to FS-OPCAB.

Distribution and function of sodium channel subtypes in human atrial myocardium.

Voltage-gated sodium channels composed of a pore-forming α subunit and auxiliary ß subunits are responsible for the upstroke of the action potential in cardiac muscle. However, their localization and expression patterns in human myocardium have not yet been clearly defined. We used immunohistochemical methods to define the level of expression and the subcellular localization of sodium channel α and ß subunits in human atrial myocytes. Nav1.2 channels are located in highest density at intercalated disks where ß1 and ß3 subunits are also expressed. Nav1.4 and the predominant Nav1.5 channels are located in a striated pattern on the cell surface at the z-lines together with ß2 subunits. Nav1.1, Nav1.3, and Nav1.6 channels are located in scattered puncta on the cell surface in a pattern similar to ß3 and ß4 subunits. Nav1.5 comprised approximately 88% of the total sodium channel staining, as assessed by quantitative immunohistochemistry. Functional studies using whole cell patch-clamp recording and measurements of contractility in human atrial cells and tissue showed that TTX-sensitive (non-Nav1.5) α subunit isoforms account for up to 27% of total sodium current in human atrium and are required for maximal contractility. Overall, our results show that multiple sodium channel α and ß subunits are differentially localized in subcellular compartments in human atrial myocytes, suggesting that they play distinct roles in initiation and conduction of the action potential and in excitation-contraction coupling. TTX-sensitive sodium channel isoforms, even though expressed at low levels relative to TTX-sensitive Nav1.5, contribute substantially to total cardiac sodium current and are required for normal contractility. This article is part of a Special Issue entitled "Na(+) Regulation in Cardiac Myocytes".

Clampless off-pump versus conventional coronary artery revascularization: a propensity score analysis of 788 patients.

BACKGROUND: This study aimed to assess if clampless off-pump coronary artery bypass grafting (CABG) decreases risk-adjusted mortality, stroke rate, and morbidity in unselected patients in comparison to conventional CABG. METHODS AND RESULTS: Between July 2009 and November 2010, data of 1282 consecutive patients undergoing isolated CABG were prospectively recorded. In 30.8% (n=395), clampless off-pump revascularization was used, either with the PAS-Port automated central venous anastomosis system (n=310) or as total arterial revascularization without central anastomoses (n=85). Propensity score (PS) matching was performed based on 15 preoperative risk variables to correct for selection bias. In-hospital mortality and stroke rate as primary end point, as well as major complications and follow-up outcome of clampless off-pump (lessOPCAB) and conventional CABG (cCABG) were compared in 394 matched patient pairs (total: 788 patients). The clampless off-pump technique decreased the in-hospital rate of death (odds ratio, 0.25; 95% confidence interval, 0.05-1.18, P=0.080) and stroke (odds ratio, 0.36; 95% confidence interval, 0.13-0.99, P=0.048) significantly. Complications such as low cardiac output syndrome, prolonged ventilation and rethoracotomy were also reduced by lessOPCAB. Over a 2-year follow-up period overall survival, cerebrovascular and major adverse event rate were significantly lower in the lessOPCAB group, while the repeat revascularization rate was comparable. CONCLUSIONS: In a retrospective PS-matched analysis, clampless off-pump CABG lowers mortality, stroke rate and other morbidity in an unselected group of patients with coronary artery disease.

Inhibition of elevated Ca2+/calmodulin-dependent protein kinase II improves contractility in human failing myocardium.

RATIONALE: Heart failure (HF) is known to be associated with increased Ca(2+)/calmodulin-dependent protein kinase (CaMK)II expression and activity. There is still controversial discussion about the functional role of CaMKII in HF. Moreover, CaMKII inhibition has never been investigated in human myocardium. OBJECTIVE: We sought to investigate detailed CaMKIIδ expression in end-stage failing human hearts (dilated and ischemic cardiomyopathy) and the functional effects of CaMKII inhibition on contractility. METHODS AND RESULTS: Expression analysis revealed that CaMKIIδ, both cytosolic δ(C) and nuclear δ(B) splice variants, were significantly increased in both right and left ventricles from patients with dilated or ischemic cardiomyopathy versus nonfailing. Experiments with isometrically twitching trabeculae revealed significantly improved force frequency relationships in the presence of CaMKII inhibitors (KN-93 and AIP). Increased postrest twitches after CaMKII inhibition indicated an improved sarcoplasmic reticulum (SR) Ca(2+) loading. This was confirmed in isolated myocytes by a reduced SR Ca(2+) spark frequency and hence SR Ca(2+) leak, resulting in increased SR Ca(2+) load when inhibiting CaMKII. Ryanodine receptor type 2 phosphorylation at Ser2815, which is known to be phosphorylated by CaMKII thereby contributing to SR Ca(2+) leak, was found to be markedly reduced in KN-93-treated trabeculae. Interestingly, CaMKII inhibition did not influence contractility in nonfailing sheep trabeculae. CONCLUSIONS: The present study shows for the first time that CaMKII inhibition acutely improves contractility in human HF where CaMKIIδ expression is increased. The mechanism proposed consists of a reduced SR Ca(2+) leak and consequently increased SR Ca(2+) load. Thus, CaMKII inhibition appears to be a possible therapeutic option for patients with HF and merits further investigation.

Mild metabolic acidosis impairs the ß-adrenergic response in isolated human failing myocardium.

INTRODUCTION: Pronounced extracellular acidosis reduces both cardiac contractility and the ß-adrenergic response. In the past, this was shown in some studies using animal models. However, few data exist regarding how the human end-stage failing myocardium, in which compensatory mechanisms are exhausted, reacts to acute mild metabolic acidosis. The aim of this study was to investigate the effect of mild metabolic acidosis on contractility and the ß-adrenergic response of isolated trabeculae from human end-stage failing hearts. METHODS: Intact isometrically twitching trabeculae isolated from patients with end-stage heart failure were exposed to mild metabolic acidosis (pH 7.20). Trabeculae were stimulated at increasing frequencies and finally exposed to increasing concentrations of isoproterenol (0 to 1 × 10(-6) M). RESULTS: A mild metabolic acidosis caused a depression in twitch-force amplitude of 26% (12.1 ± 1.9 to 9.0 ± 1.5 mN/mm(2); n = 12; P < 0.01) as compared with pH 7.40. Force-frequency relation measurements yielded no further significant differences of twitch force. At the maximal isoproterenol concentration, the force amplitude was comparable in each of the two groups (pH 7.40 versus pH 7.20). However, the half-maximal effective concentration (EC50) was significantly increased in the acidosis group, with an EC50 of 5.834 × 10(-8) M (confidence interval (CI), 3.48 × 10(-8) to 9.779 × 10(-8); n = 9), compared with the control group, which had an EC50 of 1.056 × 10(-8) M (CI, 2.626 × 10(-9) to 4.243 × 10(-8); n = 10; P < 0.05), indicating an impaired ß-adrenergic force response. CONCLUSIONS: Our data show that mild metabolic acidosis reduces cardiac contractility and significantly impairs the ß-adrenergic force response in human failing myocardium. Thus, our results could contribute to the still-controversial discussion about the therapy regimen of acidosis in patients with critical heart failure.

Different activation of MAPKs and Akt/GSK3ß after preload vs. afterload elevation.

AIMS: Pressure overload (PO) and volume overload (VO) lead to concentric or eccentric hypertrophy. Previously, we could show that activation of signalling cascades differ in in vivo mouse models. Activation of these signal cascades could either be induced by intrinsic load sensing or neuro-endocrine substances like catecholamines or the renin-angiotensin-aldosterone system. METHODS AND RESULTS: We therefore analysed the activation of classical cardiac signal pathways [mitogen-activated protein kinases (MAPKs) (ERK, p38, and JNK) and Akt-GSK3ß] in in vitro of mechanical overload (ejecting heart model, rabbit and human isolated muscle strips). Selective elevation of preload in vitro increased AKT and GSK3ß phosphorylation after 15 min in isolated rabbit muscles strips (AKT 49%, GSK3ß 26%, P < 0.05) and in mouse ejecting hearts (AKT 51%, GSK49%, P < 0.05), whereas phosphorylation of MAPKs was not influenced by increased preload. Selective elevation of afterload revealed an increase in ERK phosphorylation in the ejecting heart (43%, P < 0.05), but not in AKT, GSK3ß, and the other MAPKs. Elevation of preload and afterload in the ejecting heart induced a significant phosphorylation of ERK (95%, P < 0.001) and showed a moderate increased AKT (P = 0.14) and GSK3ß (P = 0.21) phosphorylation, which did not reach significance. Preload and afterload elevation in muscles strips from human failing hearts showed neither AKT nor ERK phosphorylation changes. CONCLUSIONS: Our data show that preload activates the AKT-GSK3ß and afterload the ERK pathway in vitro, indicating an intrinsic mechanism independent of endocrine signalling.

Misleading Germ Cell Phenotype in Pulmonary NUT Carcinoma Harboring the ZNF532-NUTM1 Fusion.

NUT carcinoma (aka NUT midline carcinoma) is a rare, still significantly underrecognized aggressive malignancy. Although historically considered a midline malignancy of children and young adults, NUT carcinoma can originate in almost any body site and in any age group. Beside the classic BRD4-NUTM1 fusion, less common fusion partners include BRD3, NSD3, ZNF532, and ZNF592. Other fusions, including CIC, MGA, MXD4, MXD1, and BCORL1 are associated with sarcomas or cancers of unknown histogenesis. Involvement of the Z4 zinc finger protein (ZNF) family members ZNF532 and ZNF592 is exceedingly rare with only 3 recently reported cases. We herein describe a ZNF532-NUTM1-rearranged NUT carcinoma presenting as a 7.5 cm mass in the left lower lung lobe of a 65-year-old woman. Histology revealed undifferentiated monotonous small round cells with focal epithelioid and rhabdoid elements within a variably myxoid stroma. Immunohistochemistry revealed paucity of keratins and variable p63 combined with extensive CD30 and PLAP expression, leading to initial diagnoses of combined small cell carcinoma, CD30-positive unclassified hematolymphoid malignancy and malignant germ cell neoplasm. Negativity for other more specific germ cell markers justified seeking a fourth opinion, which revealed diffuse expression of the NUT antibody. The diagnosis was then confirmed by fluorescence in situ hybridization. Targeted RNA sequencing revealed the ZNF532-NUTM1 fusion. Screening of 7 NUT carcinomas (5 with BRD4-NUTM1 and 2 with NSD3-NUTM1 fusions) for germ cell markers revealed focal SALL4 reactivity in 3 cases (combined with variable AFP expression in 2), but none expressed CD30 or PLAP. An aberrant germ cell immunophenotype should be considered in NUT carcinoma to avoid misinterpretation as genuine germ cell malignancy as both diseases predominantly affect the young population, frequently involve the mediastinum and can be associated with elevated serum AFP.

Impact of left atrial appendage fibrosis on atrial fibrillation in patients following coronary bypass surgery.

OBJECTIVES: We aimed to assess the relationship of left atrial appendage (LAA) fibrosis with atrial fibrillation (AF) and postoperative events in patients receiving coronary artery bypass graft surgery (CABG). BACKGROUND: Increased atrial fibrosis has been associated with AF and worse outcome following catheter ablation. Only limited data exists focusing on the impact of LAA fibrosis on AF after CABG. METHODS: LAA tissue from 164 CABG-patients was stained with Masson-Goldner trichrome. The histological landscape was scanned and segmented into superpixels for software analysis (QuPath). A classification algorithm was extensively trained to detect fibrotic superpixels for quantification. In 43 propensity score matched pairs with AF or sinus rhythm (SR), LAA fibrosis was compared. Moreover, subgroups of mitral valve regurgitation (MR) were analyzed as follows: SR, SR + MR, AF and AF + MR. The predictive value of LAA fibrosis postoperative stroke, postoperative AF and mortality was assessed. RESULTS: Fibrotic remodeling (%) showed no significant difference for the total cohort between the SR and AF group (SR: 30.8 ± 11.4% and AF: 33.8 ± 16.0%, respectively, p = .32). However, significant fibrotic remodeling was observed for SR and AF subgroups (SR: 27.2 ± 12.2% vs. AF: 35.3 ± 13.7%; respectively, p = .049) and between SR and SR + MR subgroups (SR: 27.2 ± 12.2% vs. SR + MR: 34.9 ± 9.1%, respectively, p = .027). LAA fibrosis was not significantly associated with postoperative stroke, postoperative AF or overall mortality (all p > .05). CONCLUSION: LAA fibrosis may contribute to an individual arrhythmia substrate for AF in patients with AF but also in those with SR and coincidence of MR. LAA fibrosis was not found to be predictive for clinical events in patients after CABG.

Risk-adjusted analysis of long-term outcomes after on- versus off-pump coronary artery bypass grafting.

OBJECTIVES: Recent data suggested that off-pump coronary artery bypass (OPCAB) may carry a higher risk for mortality in the long term when compared to on-pump coronary artery bypass (ONCAB). We, therefore, compared long-term survival and morbidity in patients undergoing ONCAB versus OPCAB in a large single-centre cohort. METHODS: A total of 8981 patients undergoing isolated elective/urgent coronary artery bypass grafting between January 2009 and December 2019 were analysed. Patients were stratified into 2 groups (OPCAB n = 6649/ONCAB n = 2332). The primary end point was all-cause mortality. Secondary endpoints included repeat revascularization, stroke and myocardial infarction. To adjust for potential selection bias, 1:1 nearest neighbour propensity score (PS) matching was performed resulting in 1857 matched pairs. Moreover, sensitivity analysis was applied in the entire study cohort using multivariable- and PS-adjusted Cox regression analysis. RESULTS: In the PS-matched cohort, 10-year mortality was similar between study groups [OPCAB 36.4% vs ONCAB 35.8%: hazard ratio (HR) 0.99, 95% confidence interval (CI) 0.87-1.12; P = 0.84]. While 10-year outcomes of secondary endpoints did not differ significantly, risk of stroke (OPCAB 1.50% vs ONCAB 2.8%: HR 0.51, 95% CI 0.32-0.83; P = 0.006) and mortality (OPCAB 3.1% vs ONCAB 4.8%: HR 0.65, 95% CI 0.47-0.91; P = 0.011) at 1 year was lower in the OPCAB group. In the multivariable- and the PS-adjusted model, mortality at 10 years was not significantly different (OPCAB 34.1% vs ONCAB 35.7%: HR 0.97, 95% CI 0.87-1.08; P = 0.59 and HR 1.01, 95% CI 0.90-1.13; P = 0.91, respectively). CONCLUSIONS: Data do not provide evidence that elective/urgent OPCAB is associated with significantly higher risks of mortality, repeat revascularization, or myocardial infarction during late follow-up when compared to ONCAB. Patients undergoing OPCAB may benefit from reduced risks of stroke and mortality within the first year postoperatively.