C-type natriuretic peptide moderates titin-based cardiomyocyte stiffness

Heart failure is often accompanied by titin-dependent myocardial stiffness. Phosphorylation of titin by cGMP-dependent protein kinase I (PKGI) increases cardiomyocyte distensibility. The upstream pathways stimulating PKGI-mediated titin phosphorylation are unclear. We studied whether C-type natriuretic peptide (CNP), via its guanylyl cyclase-B (GC-B) receptor and cGMP/PKGI signaling, modulates titin-based ventricular compliance. To dissect GC-B–mediated effects of endogenous CNP in cardiomyocytes, we generated mice with cardiomyocyte-restricted GC-B deletion (CM GC-B–KO mice). The impact on heart morphology and function, myocyte passive tension, and titin isoform expression and phosphorylation was studied at baseline and after increased afterload induced by transverse aortic constriction (TAC). Pressure overload increased left ventricular endothelial CNP expression, with an early peak after 3 days. Concomitantly, titin phosphorylation at Ser₄₀₈₀, the site phosphorylated by PKGI, was augmented. Notably, in CM GC-B–KO mice this titin response was abolished. TAC-induced hypertrophy and fibrosis were not different between genotypes. However, the KO mice presented mild systolic and diastolic dysfunction together with myocyte stiffness, which were not observed in control littermates. In vitro, recombinant PKGI rescued reduced titin-Ser₄₀₈₀ phosphorylation and reverted passive stiffness of GC-B–deficient cardiomyocytes. CNP-induced activation of GC-B/cGMP/PKGI signaling in cardiomyocytes provides a protecting regulatory circuit preventing titin-based myocyte stiffening during early phases of pressure overload.

C-type natriuretic peptide via GC-B/cGMP/PKGI signalling in cardiomyocytes attenuates titin-based cardiomyocyte stiffening during early phases of pressure-overload.

Outcomes after transcatheter aortic valve replacement in older patients

Background

The prevalence of aortic valve stenosis is increasing due to the continuously growing geriatric population. Data on procedural success and mortality of very old patients are sparse, raising the question of when this population may be deemed as “too old even for transcatheter aortic valve replacement (TAVR).” We, therefore, sought to evaluate the influence of age on outcome after TAVR and the impact of direct implantation.

Methods

The data of 394 consecutive patients undergoing TF-TAVR were analyzed. Patients were divided into four age groups: ≤75 (group 1, n = 28), 76–80 (group 2, n = 107), 81–85 (group 3, n = 148), and >85 (group 4, n = 111) years. Direct implantation was performed when possible according to current recommendations. Survival was evaluated by Kaplan–Meier analysis.

Results

Mortality at 30 days and 1 year was not significantly different between the four age groups (3.6 vs. 6.7 vs. 5.4 vs. 2.7% and 7.6 vs. 17 vs. 14.5 vs. 13%m respectively, log-rank p = 0.59). Direct implantation without balloon aortic valvuloplasty was more frequently performed on patients aged >85 vs. ≤85 years (33.3 vs. 14.1%, p < 0.001). the incidence of procedural complications frequently associated with advanced age (stroke, vascular complications) was not significantly increased in group 4.

Conclusion

Outcome after TF-TAVR is comparable among different age cohorts, even in very old patients. Direct implantation simplifies the procedure and could therefore play a role in reducing the incidence of peri-interventional complications in patients of advanced age.

Oversized versus Non-oversized Prosthesis: Midterm Outcomes after Transcatheter Aortic Valve Replacement Using SAPIEN 3 Valve

BACKGROUND

 A certain degree of prosthesis oversizing is recommended for the SAPIEN 3 (S3; Edwards Lifesciences Corp., Irvine, California, United States) to ensure device success. We aimed to investigate midterm outcomes in patients who received oversized (OS) S3 valve after transapical-transcatheter aortic valve replacement (TA-TAVR).

METHODS

 Out of 122 patients with aortic stenosis who underwent TA-TAVR using S3 at our institution, 42 received OS prosthesis. We used computed tomography (CT) derived effective diameter to assess oversizing. We defined oversizing if the labeled diameter of the selected valve for implantation was ≥2 mm bigger than the effective annulus diameter calculated by the annulus area. We conducted a midterm follow-up and compared the OS cohort with the non-OS (nOS) cohort.

RESULTS

 The study groups showed similar risk score and age (STS [Society of Thoracic Surgery] score: 5.4 ± 3; mean age: 80.7 ± 5.7). The 30-day mortality was 7.1% in OS versus 2.4% in nOS. The 30-day all-stroke was 2.4% in OS versus 0% in nOS. The 1- and 3-year all-cause mortality were 28.5 and 42.8% in OS versus 21.9 and 26.8% in nOS, respectively. Midterm freedom from death and from cardiocerebral events was similar in both groups. Moderate/severe paravalvular leakage occurred in 0% in OS versus 5.4% in nOS. The postdilation rate was 7.1% in OS versus 15.3% in nOS. The rate of new permanent pacemaker implantation (PPI) was 15.7% in OS versus 9.3% in nOS. The STS score was detected as an independent predictor of mortality.

CONCLUSION

 Oversizing reduces the risk of device failure and intraprocedural postdilation but increases the risk of PPI. Early and midterm morbidity and mortality after OS and nOS with S3 are comparable.

CaMKII activity contributes to homeometric autoregulation of the heart: A novel mechanism for the Anrep effect

KEY POINTS

The Anrep effect represents the alteration of left ventricular (LV) contractility to acutely enhanced afterload in a few seconds, thereby preserving stroke volume (SV) at constant preload. As a result of the missing preload stretch in our model, the Anrep effect differs from the slow force response and has a different mechanism. The Anrep effect demonstrated two different phases. First, the sudden increased afterload was momentary equilibrated by the enhanced LV contractility as a result of higher power strokes of strongly-bound myosin cross-bridges. Second, the slightly delayed recovery of SV is perhaps dependent on Ca²⁺ /calmodulin-dependent protein kinase II activation caused by oxidation and myofilament phosphorylation (cardiac myosin-binding protein-C, myosin light chain 2), maximizing the recruitment of available strongly-bound myosin cross-bridges. Short-lived oxidative stress might present a new facet of subcellular signalling with respect to cardiovascular regulation. Relevance for human physiology was demonstrated by echocardiography disclosing the Anrep effect in humans during handgrip exercise.

ABSTRACT

The present study investigated whether oxidative stress and Ca²⁺ /calmodulin-dependent protein kinase II (CaMKII) activity are involved in triggering the Anrep effect. LV pressure-volume (PV) analyses of isolated, preload controlled working hearts were performed at two afterload levels (60 and 100 mmHg) in C57BL/6N wild-type (WT) and CaMKII-double knockout mice (DKO^CaMKII ). In snap-frozen WT hearts, force-pCa relationship, H₂ O₂ generation, CaMKII oxidation and phosphorylation of myofilament and Ca²⁺ handling proteins were assessed. Acutely raised afterload showed significantly increased wall stress, H₂ O₂ generation and LV contractility in the PV diagram with an initial decrease and recovery of stroke volume, whereas end-diastolic pressure and volume, as well as heart rate, remained constant. Afterload induced increase in LV contractility was blunted in DKO^CaMKII -hearts. Force development of single WT cardiomyocytes was greater with elevated afterload at submaximal Ca²⁺ concentration and associated with increases in CaMKII oxidation and phosphorylation of cardiac-myosin binding protein-C, myosin light chain and Ca²⁺ handling proteins. CaMKII activity is involved in the regulation of the Anrep effect and associates with stimulation of oxidative stress, presumably starting a cascade of CaMKII oxidation with downstream phosphorylation of myofilament and Ca²⁺ handling proteins. These mechanisms improve LV inotropy and preserve stroke volume within few seconds.

NT-proBNP for risk prediction of cardiovascular events and all-cause mortality: The getABI-study

Background

Beside their role in the diagnosis of heart failure in symptomatic patients with dyspnea, natriuretic peptides have been suggested to improve risk prediction of cardiac events and mortality in asymptomatic cohorts. We aimed to evaluate the prognostic value of NT-proBNP for cardiovascular and all-cause mortality above traditional risk factors in a prospective cohort study of unselected elderly patients in a representative primary care setting.

Methods

We followed 6382 patients of the getABI-study for 7 years. Associations of NT-proBNP levels (≤125; 125-300; >300pg/ml for all) with all-cause and cardiovascular mortality were assessed using cox regression analysis.

Results

The incidence of all-cause and cardiovascular mortality was higher in subjects with higher levels of NT-proBNP (all-cause mortality/cardiovascular mortality: 35.4%/6% for NT-proBNP > 300 pg/ml; 16.2%/40% for NT-proBNP 125-300 pg/ml vs. 11.4%/4% for NT-proBNP ≤ 125 pg/ml. Participants with a NT-proBNP levels > 300pg/ml had increased incidence of hard endpoint (hazard ratio (HR) (95% confidence interval (CI)): 3.62 (3.15-4.17) for all-cause mortality, and 6.38 (4.84-8.41) for cardiovascular mortality). These associations remained after adjustment for traditional risk factors and cardiac medications and diseases (HR = 2.64 (2.26-3.08) for all-cause mortality, and HR = 3.93 (2.90-5.32) for cardiovascular mortality).

Conclusion

Our results show strong associations of higher NT-proBNP levels with cardiovascular and all-cause mortality in an unselected, large population of elderly patients in the primary care setting independent of traditional risk factors indicating that NT-proBNP can help identifying subjects at high risk for cardiac events.

Enhanced Cardiomyocyte Function in Hypertensive Rats With Diastolic Dysfunction and Human Heart Failure Patients After Acute Treatment With Soluble Guanylyl Cyclase (sGC) Activator

Aims

Our aim was to investigate the effect of nitric oxide (NO)-independent activation of soluble guanylyl cyclase (sGC) on cardiomyocyte function in a hypertensive animal model with diastolic dysfunction and in biopsies from human heart failure with preserved ejection fraction (HFpEF).

Methods

Dahl salt-sensitive (DSS) rats and control rats were fed a high-salt diet for 10 weeks and then acutely treated in vivo with the sGC activator BAY 58-2667 (cinaciguat) for 30 min. Single skinned cardiomyocyte passive stiffness (F_passive) was determined in rats and human myocardium biopsies before and after acute treatment. Titin phosphorylation, activation of the NO/sGC/cyclic guanosine monophosphate (cGMP)/protein kinase G (PKG) cascade, as well as hypertrophic pathways including NO/sGC/cGMP/PKG, PKA, calcium–calmodulin kinase II (CaMKII), extracellular signal-regulated kinase 2 (ERK2), and PKC were assessed. In addition, we explored the contribution of pro-inflammatory cytokines and oxidative stress levels to the modulation of cardiomyocyte function. Immunohistochemistry and electron microscopy were used to assess the translocation of sGC and connexin 43 proteins in the rat model before and after treatment.

Results

High cardiomyocyte F_passive was found in rats and human myocardial biopsies compared to control groups, which was attributed to hypophosphorylation of total titin and to deranged site-specific phosphorylation of elastic titin regions. This was accompanied by lower levels of PKG and PKA activity, along with dysregulation of hypertrophic pathway markers such as CaMKII, PKC, and ERK2. Furthermore, DSS rats and human myocardium biopsies showed higher pro-inflammatory cytokines and oxidative stress compared to controls. DSS animals benefited from treatment with the sGC activator, as F_passive, titin phosphorylation, PKG and the hypertrophic pathway kinases, pro-inflammatory cytokines, and oxidative stress markers all significantly improved to the level observed in controls. Immunohistochemistry and electron microscopy revealed a translocation of sGC protein toward the intercalated disc and t-tubuli following treatment in both control and DSS samples. This translocation was confirmed by staining for the gap junction protein connexin 43 at the intercalated disk. DSS rats showed a disrupted connexin 43 pattern, and sGC activator was able to partially reduce disruption and increase expression of connexin 43. In human HFpEF biopsies, the high F_passive, reduced titin phosphorylation, dysregulation of the NO–sGC–cGMP–PKG pathway and PKA activity level, and activity of kinases involved in hypertrophic pathways CaMKII, PKC, and ERK2 were all significantly improved by sGC treatment and accompanied by a reduction in pro-inflammatory cytokines and oxidative stress markers.

Conclusion

Our data show that sGC activator improves cardiomyocyte function, reduces inflammation and oxidative stress, improves sGC–PKG signaling, and normalizes hypertrophic kinases, indicating that it is a potential treatment option for HFpEF patients and perhaps also for cases with increased hypertrophic signaling.

Modulation of Titin-Based Stiffness in Hypertrophic Cardiomyopathy via Protein Kinase D

The giant protein titin performs structure-preserving functions in the sarcomere and is important for the passive stiffness (F_passive) of cardiomyocytes. Protein kinase D (PKD) enzymes play crucial roles in regulating myocardial contraction, hypertrophy, and remodeling. PKD phosphorylates myofilament proteins, but it is not known whether the giant protein titin is also a PKD substrate. Here, we aimed to determine whether PKD phosphorylates titin and thereby modulates cardiomyocyte F_passive in normal and failing myocardium. The phosphorylation of titin was assessed in cardiomyocyte-specific PKD knock-out mice (cKO) and human hearts using immunoblotting with a phosphoserine/threonine and a phosphosite-specific titin antibody. PKD-dependent site-specific titin phosphorylation in vivo was quantified by mass spectrometry using stable isotope labeling by amino acids in cell culture (SILAC) of SILAC-labeled mouse heart protein lysates that were mixed with lysates isolated from hearts of either wild-type control (WT) or cKO mice. F_passive of single permeabilized cardiomyocytes was recorded before and after PKD and HSP27 administration. All-titin phosphorylation was reduced in cKO compared to WT hearts. Multiple conserved PKD-dependent phosphosites were identified within the Z-disk, A-band and M-band regions of titin by quantitative mass spectrometry, and many PKD-dependent phosphosites detected in the elastic titin I-band region were significantly decreased in cKO. Analysis of titin site-specific phosphorylation showed unaltered or upregulated phosphorylation in cKO compared to matched WT hearts. F_passive was elevated in cKO compared to WT cardiomyocytes and PKD administration lowered F_passive of WT and cKO cardiomyocytes. Cardiomyocytes from hypertrophic cardiomyopathy (HCM) patients showed higher F_passive compared to control hearts and significantly lower F_passive after PKD treatment. In addition, we found higher phosphorylation at CaMKII-dependent titin sites in HCM compared to control hearts. Expression and phosphorylation of HSP27, a substrate of PKD, were elevated in HCM hearts, which was associated with increased PKD expression and phosphorylation. The relocalization of HSP27 in HCM away from the sarcomeric Z-disk and I-band suggested that HSP27 failed to exert its protective action on titin extensibility. This protection could, however, be restored by administration of HSP27, which significantly reduced F_passive in HCM cardiomyocytes. These findings establish a previously unknown role for PKDin regulating diastolic passive properties of healthy and diseased hearts.

Infantile restrictive cardiomyopathy: cTnI-R170G/W impair the interplay of sarcomeric proteins and the integrity of thin filaments

TNNI3 encoding cTnI, the inhibitory subunit of the troponin complex, is the main target for mutations leading to restrictive cardiomyopathy (RCM). Here we investigate two cTnI-R170G/W amino acid replacements, identified in infantile RCM patients, which are located in the regulatory C-terminus of cTnI. The C-terminus is thought to modulate the function of the inhibitory region of cTnI. Both cTnI-R170G/W strongly enhanced the Ca²⁺-sensitivity of skinned fibres, as is typical for RCM-mutations. Both mutants strongly enhanced the affinity of troponin (cTn) to tropomyosin compared to wildtype cTn, whereas binding to actin was either strengthened (R170G) or weakened (R170W). Furthermore, the stability of reconstituted thin filaments was reduced as revealed by electron microscopy. Filaments containing R170G/W appeared wavy and showed breaks. Decoration of filaments with myosin subfragment S1 was normal in the presence of R170W, but was irregular with R170G. Surprisingly, both mutants did not affect the Ca²⁺-dependent activation of reconstituted cardiac thin filaments. In the presence of the N-terminal fragment of cardiac myosin binding protein C (cMyBPC-C0C2) cooperativity of thin filament activation was increased only when the filaments contained wildtype cTn. No effect was observed in the presence of cTn containing R170G/W. cMyBPC-C0C2 significantly reduced binding of wildtype troponin to actin/tropomyosin, but not of both mutant cTn. Moreover, we found a direct troponin/cMyBPC-C0C2 interaction using microscale thermophoresis and identified cTnI and cTnT, but not cTnC as binding partners for cMyBPC-C0C2. Only cTn containing cTnI-R170G showed a reduced affinity towards cMyBPC-C0C2. Our results suggest that the RCM cTnI variants R170G/W impair the communication between thin and thick filament proteins and destabilize thin filaments.

[Appropriate procedure for pacemaker and ICD malfunction]

Malfunctions in implanted pacemaker and defibrillator systems can affect all components of the device (battery, capacitor, central processing unit (CPU), connector, soldering points, electrodes). The resulting problems can manifest themselves as inadequate therapy, a lack of therapy despite the need for stimulation or shock release in case of ventricular tachyarrhythmia, or as an ineffective delivery of therapy. The high number of implanted pacemaker and defibrillator systems, the increased life expectancy and the technical progress of cardiac "device" therapy mean that the treating physician is confronted with increasingly complex problems in the follow-up. In addition to the knowledge of the basic function of these devices, a structured procedure to detect and treat malfunctions in a timely manner is required. In this review, frequent malfunctions of pacemaker and defibrillators are presented, individual problems are pointed out, and solutions and treatment options are shown.

Heart rate variability and cardiac repolarization after exposure to zinc oxide nanoparticles in healthy adults

Background

Exposure to airborne zinc oxide (ZnO) particles occurs in many industrial processes, especially in galvanizing and welding. Systemic inflammation after experimental inhalation of ZnO particles has been demonstrated previously, but little is known about the impact on the cardiovascular system, particularly on the autonomic cardiac system and the risk of arrhythmias. In this study we investigated the short-term effects of ZnO nanoparticles on heart rate variability (HRV) and repolarization in healthy adults in a concentration-dependent manner at rest and during exercise in a controlled experimental set-up.

Methods

Sixteen healthy subjects were exposed to filtered air and ZnO particles (0.5, 1.0 and 2.0 mg/m³) for 4 h, including 2 h of cycling at low workloads. Parameters were assessed before, during, immediately after, and about 24 h after each exposure. For each subject, a total number of 46 10-min-sections from electrocardiographic records were analyzed. Various parameters of HRV and QT interval were measured.

Results

Overall, no statistically significant effects of controlled ZnO inhalation on HRV parameters and QT interval were observed. Additionally, a concentration-response was absent.

Conclusion

Inhalation of ZnO nanoparticles up to 2.0 mg/m³ for 4 h does not affect HRV and cardiac repolarization in healthy adults at the chosen time points. This study supports the view that cardiac endpoints are insensitive for the assessment of adverse effects after short-term inhalation of ZnO nanoparticles.

Risk stratification in patients undergoing interventional left atrial appendage occlusion-Prognostic impact of EuroSCORE II

Background

Interventional closure of the left atrial appendage (LAA) is an alternative option to stroke prophylaxis, particularly in multimorbid patients with a high risk of bleeding under oral anticoagulation. Due to the multiple comorbidities, the prognosis of patients is reduced, and the clinical benefit of the procedure is therefore questionable in the individual patient.

Hypothesis

The present study aims to identify independent preprocedural risk factors to improve risk stratification in these highly selected patients.

Methods

This study consecutively included 128 patients who received an interventional LAA occlusion with Amplatzer device (St Jude Medical, St Paul, Minnesota). The preinterventional risk assessment was performed with the logistic European System for Cardiac Operative Risk Evaluation (EuroSCORE) II. The primary endpoint was all‐cause mortality. Secondary endpoints were thromboembolic events and severe bleeding.

Results

During a follow‐up of 781 ± 498 days the primary endpoint (all‐cause mortality) was reached in 35 patients (27%). The only independent predictor of mid‐term mortality was a logistic EuroSCORE II > 2% (Hazard risk [HR] 4.55, confidence interval [CI] 1.599‐12.966, P = .005). In our study, 33 patients (26%) suffered from end‐stage renal disease which was not associated with increased mortality (P = .371), increased thromboembolic events (P = .475), or severe bleeding (P = .613).

Conclusions

In patients undergoing interventional LAA occlusion, preprocedural assessment of logistic EuroSCORE II provide independent prognostic information. This parameter might help to improve risk stratification in these highly selected patients. In contrast, terminal renal failure was not associated with a significantly worse outcome.

Feasibility of the Figure-of-8-Suture as Venous Closure in Interventional Electrophysiology: One Strategy for All?

Background: Venous vascular access with higher sheath size is common in interventional electrophysiology. In contrast to arterial vascular access, no dedicated closure devices exist for closure after venous access with higher sheath sizes. The Figure-of-8-Suture, an easy to apply suture, may be as a feasible approach for closure venous puncture. Our aim was to evaluate the feasibility of closure of femoral venous access. Methods: From November 2016 to February 2018, patients undergoing electrophysiological procedures, closure of left atrial appendage or patent foramen ovale were included. Until May 2017, manual compression was performed to achieve haemostasis at venous access site (control group). From May 2017, patients were treated with a Figure-of-8-Suture (treatment group, Figure 1). Turnaround time and incidence of vascular complications were compared between the two groups. Results: In total, 290 patients were included, 132 in the control group and 158 in the Figure-of-8-Suture group. Hemostasis after sheath removal was achieved in 100% of the cases in the control group by manual compression and in 98.7% of the cases with the Figure-of-8-Suture (p=0.2). Vascular complications were more common in the control group (6.8 vs. 1.3 %, p=0.01). Turnaround time was significantly lower in the Figure-of-8-Suture group (58.6 ± 14 vs. 77 ± 33.9 min, p=0.004). In a sub-analysis in obese patients with body mass index (BMI) ≥30 kg/m² (Figure-of-8 n=45, controls n=35), vascular complications were significantly more common in the control group (9.4 vs 0%, p=0.045). Conclusion: The Figure-of-8-Suture is an easy-to-apply, effective approach for venous closure after electrophysiological procedures.

Feasibility of Transfemoral Aortic Valve Implantation in Patients With Aortic Disease and Simultaneous or Sequential Endovascular Aortic Repair

OBJECTIVES

The transfemoral approach for transcatheter aortic valve implantation (TF-TAVI) is associated with a significant survival benefit for intermediate and high-risk patients. Due to the increased procedural risk, many operators avoid TF-TAVI in patients with aortic disease. Moreover, significant peri-interventional device interaction may occur in patients with previous endovascular aortic repair (EVAR). We evaluated the feasibility of TF-TAVI in patients with aortic disease in combination with simultaneous or sequential EVAR.

METHODS

Data from 15 TF-TAVI patients with concomitant aortic disease treated between 2009 and 2019 in three German heart centers representing 4410 TAVI procedures were analyzed.

RESULTS

Two patients with progressive penetrating atherosclerotic ulcers (PAUs) in the descending thoracic aorta underwent sequential and simultaneous thoracic EVAR (TEVAR), respectively. One patient with stable PAU and 4 patients with not yet relevant abdominal aortic aneurysm (AAA) underwent isolated TF-TAVI. One patient with relevant AAA underwent TF-TAVI and sequential EVAR. Seven patients with previous EVAR due to an AAA underwent TF-TAVI (5 with a bifurcated graft and 2 with a straight graft). TF-TAVI and sequential or simultaneous TEVAR were technically successful in all patients. Vascular complications occurred in 1 patient. One patient died within 30 days and 2 patients died within 12 months.

CONCLUSION

TF-TAVI can be performed successfully in patients with aortic disease or previous endovascular aortoiliac intervention. Simultaneous and sequential (T)EVAR is feasible.

Social Gradients in Myocardial Infarction and Stroke Diagnoses in Emergency Medicine

BACKGROUND

Persons of lower socio-economic status are at higher risk of disease, especially with respect to severe and chronic illnesses. To date, there have not been any studies with large case numbers regarding acute medical emergencies in this population.

METHODS

In a retrospective study, data were obtained on all cases treated by emergency physicians in Bochum, Germany, in 2014/2015, including the diagnoses that were made by the emergency physicians. There were a total of 16 767 cases. The local unemployment rate was taken as an indicator of the socioeconomic situation of a neighborhood; it was defined as the percentage of registered unemployed persons among persons aged 15 to 64 with their domicile in the neighborhood. 12 168 cases were grouped by emergency medical diagnosis and analyzed with respect to the three most heavily represented diagnostic categories (cardiovascular, neurological, and pulmonary emergencies), which accounted for nearly two-thirds of all diagnoses.

RESULTS

The overall rates of deployment involving emergency physicians were found to be positively correlated with the unemployment rate. After adjustment for age, sex, and possible confounders, this correlation was statistically significant (p<0.01). The indirectly standardized rate ratio (IRR) for the overall case-activity rate ranged from 0.841 (95% confidence interval: [0.808; 0.875]) with less than 5% unemployment to 1.212 [1.168; 1.256] with 9.5% unemployment or higher. The same finding was obtained with respect to diagnosis-specific case activity in each of the three main diagnostic categories (cardiovascular, neurological, and pulmonary emergencies), as well as for the respective commonest individual diagnoses (acute coronary syndrome/circulatory arrest [1498 cases], transient ischemic attack/ischemic stroke/intracerebral hemorrhage [1274 cases], and asthma/chronic obstructive pulmonary disease [663 cases]).

CONCLUSION

This study shows that the case-activity rate of the emergency medical services is significantly higher in socially disadvantaged neighborhoods, both with respect to total numbers and with respect to individual diseases. It demonstrates a problem affecting society as a whole, which should be taken into account in the organization of medical rescue services.

Platelet reactivity and clinical outcomes in acute coronary syndrome patients treated with prasugrel and clopidogrel: a pre-specified exploratory analysis from the TROPICAL-ACS trial

Aims

The value of platelet function testing (PFT) in predicting clinical outcomes and guiding P2Y12-inhibitor treatment is uncertain. In a pre-specified sub-study of the TROPICAL-ACS trial, we assessed ischaemic and bleeding risks according to high platelet reactivity (HPR) and low platelet reactivity (LPR) to ADP in patients receiving uniform prasugrel vs. PFT-guided clopidogrel or prasugrel.

Methods and results

Acute coronary syndrome patients with PFT done 14 days after hospital discharge were included with prior randomization to uniform prasugrel for 12 months (control group, no treatment modification) vs. early de-escalation from prasugrel to clopidogrel and PFT-guided maintenance treatment (HPR: switch-back to prasugrel, non-HPR: clopidogrel). The composite ischaemic endpoint included cardiovascular death, myocardial infarction, or stroke, while key safety outcome was Bleeding Academic Research Consortium (BARC) 2–5 bleeding, from PFT until 12 months. We identified 2527 patients with PFT results available: 1266 were randomized to the guided and 1261 to the control group. Before treatment adjustment, HPR was more prevalent in the guided group (40% vs. 15%), while LPR was more common in control patients (27% vs. 11%). Compared to control patients without HPR on prasugrel (n = 1073), similar outcomes were observed in guided patients kept on clopidogrel [n = 755, hazard ratio (HR): 1.06 (0.57–1.95), P = 0.86] and also in patients with HPR on clopidogrel switched to prasugrel [n = 511, HR: 0.96 (0.47–1.96), P = 0.91]. In contrast, HPR on prasugrel was associated with a higher risk for ischaemic events in control patients [n = 188, HR: 2.16 (1.01–4.65), P = 0.049]. Low platelet reactivity was an independent predictor of bleeding [HR: 1.74 (1.18–2.56), P = 0.005], without interaction (Pint = 0.76) between study groups.

Conclusion

Based on this substudy of a randomized trial, selecting prasugrel or clopidogrel based on PFT resulted in similar ischaemic outcomes as uniform prasugrel therapy without HPR. Although infrequent, HPR on prasugrel was associated with increased risk of ischaemic events. Low platelet reactivity was a strong and independent predictor of bleeding both on prasugrel and clopidogrel.

Hemodynamics of paradoxical severe aortic stenosis: insight from a pressure-volume loop analysis

BACKGROUND

Controversy exists about the pathophysiology of different hemodynamic subgroups of AS. In particular, the mechanism of the paradoxical low-flow, low-gradient (PLFLG) AS with preserved ejection fraction (EF) is unclear.

METHODS

A total of 41 patients with severe, symptomatic AS were divided into the following 4 subgroups based on the echocardiographically determined hemodynamics: (1) normal-flow, high-gradient (NFHG) AS; (2) low-flow, high-gradient AS; (3) paradoxical low-flow, low-gradient (PLFLG) AS with preserved EF and (4) low-flow, low-gradient (LFLG) AS with reduced EF. As part of the comprehensive invasive examinations, the analyses of the PV loops were performed with the IntraCardiac Analyzer (CD-Leycom, The Netherlands).

RESULTS

PLFLG was characterized by small left ventricular volumes as well as a decreased cardiac index, a decreased systolic contractility and a lower stroke work, than the conventional NFHG AS. Alterations in effective arterial elastance (2.36 ± 0.67 mmHg/ml in NFHG versus 3.01 ± 0.79 mmHg/ml in PLFLG, p = 0.036) and end-systolic elastance (3.72 ± 1.84 mmHg/ml in NFHG versus 5.53 ± 2.3 mmHg/ml in PLFLG, p = 0.040) indicated impaired vascular function and increased chamber stiffness.

CONCLUSIONS

The present study suggests that the hemodynamics of PLFLG AS can be explained by two mechanisms: (1) stiffness of the small left ventricle with reduced contractility, and (2) increased afterload due to the impairment of vascular function. Both mechanisms have similarities to those of heart failure with preserved EF. This type of remodeling may explain the poor prognosis of PLFLG AS.

Comparison of perioperative strategies in ICD patients: The perioperative ICD management study (PIM study)

BACKGROUND

The prevalence of patients with implanted cardioverter defibrillators (ICDs) and the frequency of surgery on these patients are steadily on the rise. Guidelines recommend preoperative ICD reprogramming, although this is sometimes difficult in clinical practice. Placing a magnet on the ICD is a practical alternative and even no inactivation is possible in selected cases.

METHODS

In this prospective observational study, we compared different perioperative ICD management strategies depending on the location of the surgery and the type of electrocautery used. Patients undergoing surgery above the umbilicus with monopolar electrocautery had their ICD therapy inactivated by reprogramming. When surgery below the navel or surgery above the navel with bipolar electrocautery was completed, ICD inactivation was performed using a magnet. No inactivation was performed on patients undergoing lower extremity surgery with bipolar electrocautery. Only ICD patients who were not pacemaker dependent were enrolled. After surgery, the ICDs were assessed regarding documented arrhythmias and parameters.

RESULTS

Out of 101 patients included in this study, the ICD was preoperatively reprogrammed in 42 patients (41.6%), a magnet was used on 45 patients (44.5%), and ICDs were not deactivated at all in 14 patients (13.9%). No intraoperative electromagnetic interference was detected. Postoperative ICD analysis demonstrated no changes of preset parameters.

CONCLUSIONS

All three tested ICD management strategies were proved safe in this study. Keeping the location of surgery and the type of electrocautery in mind, an intraoperative magnet or even no ICD deactivation at all could be feasible alternatives in surgery on patients with ICDs.

[Radiation reduction in interventional electrophysiology : Results from operators with different levels of experience]

BACKGROUND

Radiation exposure in the catherization laboratory is associated with significant health risks. It is unclear whether a reduction of radiation exposure with the use of "near-zero fluoroscopy" protocols is possible when applied by less experienced operators.

METHODS

Consecutive ablation procedures with the use of a 3D mapping system were analyzed. Three time periods were analyzed. During the first period (standard), no specific radiation-reduction protocol was used. During the second period (initial phase of radiation reduction) a near "near-zero fluoroscopy" protocol was implemented; however, the majority of procedures were performed by an expert. During the third period (routine use of radiation reduction), less experienced operators (fellow and beginner) performed a growing number of procedures with the "near-zero fluoroscopy" protocol.

RESULTS

In all, 290 procedures were analyzed. After implementation of a radiation-reduced protocol, a significant reduction of radiation exposure was observed (standard 850 ± 831.7 vs. initial phase 197.2 ± 481.8 μGy/m², p < 0.001, and vs. routine use 283 ± 493.8 μGy/m², p < 0.001). No significant difference was observed between the initial phase and routine phase (p = 1). Over the three periods, the proportion of procedures performed by less experienced operators grew significantly for complex (fellow: 0% vs. 10% vs. 30%; p < 0.001) and noncomplex procedures (fellow: 30% vs. 39% vs. 49%; beginner: 15% vs. 38% vs. 34%; p = 0.002). Complication rates were not significantly different.

CONCLUSIONS

Implementation of a radiation-reduced protocol leads to a significant reduction of radiation exposure even in less experienced operators during training.

Alterations in Titin Properties and Myocardial Fibrosis Correlate With Clinical Phenotypes in Hemodynamic Subgroups of Severe Aortic Stenosis

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The extent of myocardial fibrosis and the degree of isoform-expression and phosphorylation changes in cardiomyocyte titin were unknown in different hemodynamic subgroups of AS, including “paradoxical” low-flow, low-gradient AS with preserved ejection fraction.

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Hemodynamic subtypes of AS were found to exhibit increased cardiac fibrosis, titin-isoform transition toward more compliant N2BA variants, and both total and site-specific titin (N2Bus) hypophosphorylation compared with donor heart controls.

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A significant shift toward N2BA titin appeared in “paradoxical” AS, whereas alterations in total-titin phosphorylation and cardiac fibrosis were similar in all hemodynamic subtypes of AS, suggesting increased myocardial passive stiffness.

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The unfavorable prognosis of “paradoxical” AS could be explained by the pronounced myocardial remodeling, which is no less severe than in other AS subtypes.

Titin-isoform expression, titin phosphorylation, and myocardial fibrosis were studied in 30 patients with severe symptomatic aortic stenosis (AS). Patients were grouped into “classical” high-gradient, normal-flow AS with preserved ejection fraction (EF); “paradoxical” low-flow, low-gradient AS with preserved EF; and AS with reduced EF. Nonfailing donor hearts served as controls. AS was associated with increased fibrosis, titin-isoform switch toward compliant N2BA, and both total and site-specific titin hypophosphorylation compared with control hearts. All AS subtypes revealed titin and matrix alterations. The extent of myocardial remodeling in “paradoxical” AS was no less severe than in other AS subtypes, thus explaining the unfavorable prognosis.

Soluble adenylyl cyclase: A novel player in cardiac hypertrophy induced by isoprenaline or pressure overload

Aims

In contrast to the membrane bound adenylyl cyclases, the soluble adenylyl cyclase (sAC) is activated by bicarbonate and divalent ions including calcium. sAC is located in the cytosol, nuclei and mitochondria of several tissues including cardiac muscle. However, its role in cardiac pathology is poorly understood. Here we investigate whether sAC is involved in hypertrophic growth using two different model systems.

Methods and results

In isolated adult rat cardiomyocytes hypertrophy was induced by 24 h β₁-adrenoceptor stimulation using isoprenaline (ISO) and a β₂-adrenoceptor antagonist (ICI118,551). To monitor hypertrophy cell size along with RNA/DNA- and protein/DNA ratios as well as the expression level of α-skeletal actin were analyzed. sAC activity was suppressed either by treatment with its specific inhibitor KH7 or by knockdown. Both pharmacological inhibition and knockdown blunted hypertrophic growth and reduced expression levels of α-skeletal actin in ISO/ICI treated rat cardiomyocytes. To analyze the underlying cellular mechanism expression levels of phosphorylated CREB, B-Raf and Erk1/2 were examined by western blot. The results suggest the involvement of B-Raf, but not of Erk or CREB in the pro-hypertrophic action of sAC. In wild type and sAC knockout mice pressure overload was induced by transverse aortic constriction. Hemodynamics, heart weight and the expression level of the atrial natriuretic peptide were analyzed. In accordance, transverse aortic constriction failed to induce hypertrophy in sAC knockout mice. Mechanistic analysis revealed a potential role of Erk1/2 in TAC-induced hypertrophy.

Conclusion

Soluble adenylyl cyclase might be a new pivotal player in the cardiac hypertrophic response either to long-term β₁-adrenoceptor stimulation or to pressure overload.

Implementation of a near-zero fluoroscopy approach in interventional electrophysiology: impact of operator experience

PURPOSE

Catheter ablation is performed under fluoroscopic guidance. Reduction of radiation dose for patients and staff is emphasized by current recommendations. Previous studies have shown that lower operator experience leads to increased radiation dose. On the other hand, less experienced operators may depend even more on fluoroscopic guidance. Our study aimed to evaluate feasibility and efficacy of a non-fluoroscopic approach in different training levels.

METHODS

From January 2017, a near-zero fluoroscopy approach was established in two centers. Four operators (beginner, 1st year fellow, 2nd year fellow, expert) were instructed to perform the complete procedure with the use of a 3-D mapping system without fluoroscopy. A historical cohort that underwent procedures with fluoroscopy use served as control group. Dose area product (DPA), procedure duration, acute procedural success, and complications were compared between the groups and for each operator.

RESULTS

Procedures were performed in 157 patients. The first 100 patients underwent procedures with fluoroscopic guidance, the following 57 procedures were performed with the near-zero fluoroscopy approach. The results show a significant reduction in DPA for all operators immediately after implementation of the near-zero fluoroscopy protocol (control 637 ± 611 μGy/m²; beginner 44.1 ± 79.5 μGy/m², p = 0.002; 1st year fellow 24.3 ± 46.4.5 μGy/m², p = 0.001; 2nd year fellow 130.3 ± 233.3 μGy/m², p = 0.003; expert 9.3 ± 37.4 μGy/m², P < 0.001). Procedure duration, acute success, and complications were not significantly different between the groups.

CONCLUSION

Our results show a 90% reduction of DPA shortly after implementation of a near-zero fluoroscopy approach in interventional electrophysiology even in operators in training.