Efficacy and safety of novel left ventricular pacing leads: 1-year analysis of the NAVIGATOR trial

OBJECTIVES

Assess safety and performance of novel quadripolar preshaped left ventricular (LV) leads: NAVIGO 4LV 2D ('S shaped') and NAVIGO 4LV ARC ('U shaped').

METHODS

Patients indicated for cardiac resynchronisation therapy were enrolled in a multicentre, prospective, controlled study (NAVIGATOR, NCT03279484). Patients were implanted with either a NAVIGO 4LV 2D or ARC lead, and assessed at 10 weeks, 6, 12 and 24 months post-implant. Co-primary safety and performance endpoints were assessed at 10 weeks. Safety endpoint was the patients' rate free from lead-related complications. Performance endpoint was the rate of patients with successful lead performance, defined as LV pacing threshold ≤2.5 V at 0.5 ms on at least one pacing vector, and the absence of phrenic nerve stimulation at the final programmed configuration. Lead-related complications and electrical parameters were monitored throughout study.

RESULTS

A NAVIGO 4LV lead was successfully implanted in 211 out of 217 patients (97.2%). The safety endpoint was met, with 100% and 96.1% of patients free from complications for NAVIGO 4LV 2D and ARC, respectively. The performance endpoint was met with 98.1% and 98.9% of patients with a successful lead performance for NAVIGO 4LV 2D and ARC, respectively. Over 12 months, the global complication-free rate for both leads was 97.1% (95% CI: 93.71% to 98.70%), with a mean pacing capture threshold of 1.23 V±0.73 V and a mean impedance of 951 Ω±300.1 Ω.

CONCLUSION

A high implantation success rate and low complication rate was reported for the novel NAVIGO 4LV 2D and ARC leads, along with successful performance up to 12 months.

Why does CRT work better in women?

Introduction

It has been recently postulated that cardiac resynchronization therapy (CRT) might have a higher efficacy in women, with a greater reverse cardiac remodeling in this population. The reasons for these differences are not yet completely understood. We aimed to detect sex differences in the degree of ventricular asynchrony (VA) and mitral regurgitation (MR) in patients undergoing CRT implantation.

Methods

We analyzed baseline characteristics of a prospective international clinical trial that compared CRT response rate in a HF population with a comparable distribution of men and women (BIOWOMEN). A total of 408 patients were analyzed. The degree of mitral regurgitation and intra and inter-ventricular asynchrony was assessed by independent echocardiographers in a core lab. Inter-ventricular asynchrony was defined as an interventricular mechanical delay greater than 40ms and intra-ventricular asynchrony as differences greater than 50ms among regional pre-ejection periods. Multivariable logistic regression was performed using commercial data analysis software.

Results

As expected, ventricular asynchrony was dependent on QRS duration and the presence of LBBB (p<0.01). Baseline QRS duration was significantly shorter in women than men (155.85±19.0 in women vs 160.4±21.6, p=0.02). However, for a similar QRS duration, there were no differences in asynchrony parameters between the two groups (p=0.43; Figure 1). Female sex was associated with a significantly higher proportion of mitral regurgitation for a given QRS duration, which was independent of the etiology (p=0.05).

Conclusions

In our analysis, for a given QRS duration there was not a higher degree of asynchrony in women with HF. However, female sex was associated with a significantly higher proportion of mitral regurgitation for a given QRS duration irrespective of baseline HF etiology. Further investigations are needed to establish a possible link between these findings and better CRT outcomes in women.

Funding Acknowledgement

Type of funding sources: Private company. Main funding source(s): BIOTRONIK SE & Co. KG

P1475Impact of automatic screening and parasternal rights positions in the eligibility of patients with hypertrophic cardiomyopathy for subcutaneous automatic cardioverter defibrillator implant

Background

A high percentage of failures in the detection of QRS and T wave in patients (pts) with hypertrophic cardiomyopathy (HCM) have been reported. This finding would prevent them from being eligible for an implantable subcutaneous automatic defibrillator (S-ICD). However, recently 2 changes in the detection have been proposed, automatic screening and the use of right parasternal position of the lead. 

The aim of our work was to study if the elegibility proportion of patients  was increased with both 2 advacements.

Methods

We included 31 patients (18 male)with a diagnosis of HCM and at least 1 risk factor for sudden death, in follow-up at the outdoor clinic of of 2 cardiology centers. We performed elegibility screening test in supine position and standing using both the automatic screening (AS) obtained by Boston Scientific Zoom Latitude programmer) and the manual (MS), to simulate the detection of the 3 vectors utilized in S-ICD detection. And both screens were registered with the surface electrodes in parasternal left and right position. A pte was considered eligible if at least one vector was correct in supine position and in standing position, well in parasternal left or right position.

Results

Using MS with left parasternal position, 22 patients (71%) were eligible.  Adding the right parasternal lead, the eligibility increased by 10%,  reaching 81%. In addition, in automatic screening, eligibility in right shifts (81%) it is 7% more than in the left and, with the addition of the rights to the left, the eligibility reaches up to 84%. Figure shows the three-lead ECG factors influencing screening pass vs failure.

Conclusion

AS, right parasternal lead position and the combination of right and left parasternal lead position, increase the eligibility of sICD candidates with HCM.

Abstract Figure. ECG factors influencing screening pass

GENETIC AND GEOGRAPHIC VARIATION IN REJECTION BEHAVIOR OF CUCKOO EGGS BY EUROPEAN MAGPIE POPULATIONS: AN EXPERIMENTAL TEST OF REJECTER-GENE FLOW

Host responses toward brood parasitism have been shown to differ among populations depending on the duration of sympatry between host and parasite, although populations not currently parasitized show rejection behavior against parasitic eggs. The persistence of rejection behavior in unparasitized host populations and rapid increases of rejection rate in parasitized ones have sometimes been explained as the result of gene flow of rejecter genes from sympatry to allopatry (rejecter-gene flow hypothesis). We present data on the rejection behavior of magpies (Pica pica) the main European host of the great spotted cuckoo (Clamator glandarius), in 15 populations (nine sympatric six allopatric) across their distribution range in Europe. Rejection rates of mimetic and nonmimetic model eggs were significantly higher in sympatric than in allopatric magpie populations, although differences in rejection rate of both mimetic and nonmimetic model eggs between magpie populations were significantly correlated even after controlling tor phylogenetic effects, with differences between sympatric and allopatric magpie populations being larger for mimetic than for nonmimetic model eggs. Differences in rejection of mimetic model eggs were related to both genetic and geographic distances between populations, but differences in rejection rate of nonmimetic model eggs were unrelated to these distances. However, when comparing only sympatric populations, differences in rejection rate of both mimetic and nonmimetic model eggs were related to geographic distances. A multiple autocorrelation analysis revealed that differences among populations in rejection rates of mimetic model eggs had a strong geographic component whereas the main component of rejection rate of nonmimetic model eggs was genetic rather than geographic. These results support the rejecter-gene flow hypothesis. We discuss differences in rejection rates of mimetic and nonmimetic model eggs that suggest the egg-recognition ability of the host is genetically based, but is affected by a learning process for fine tuning of recognition.

COMPARATIVE POPULATION STRUCTURE AND GENE FLOW OF A BROOD PARASITE, THE GREAT SPOTTED CUCKOO (CLAMATOR GLANDARIUS), AND ITS PRIMARY HOST, THE MAGPIE (PICA PICA)

The amount of gene flow is an important determinant of population structure and therefore of central importance for understanding coevolutionary processes. We used microsatellite markers to estimate population structure and gene flow rates of the great spotted cuckoo (Clamator glandarius) and its main host in Europe, the magpie (Pica pica), in a number of populations (seven and 15, respectively) across their distribution range in Europe. The genetic analysis shows that there exists a pattern of isolation by distance in both species, although the cuckoo data are only indicative due to a small sample size. Gene flow seems to be extensive between nearby populations, higher for magpies than cuckoos, and especially high for magpie populations within the area of distribution of the great spotted cuckoo. There is no correlation between genetic distances between magpie populations and genetic distances between cuckoo populations. We discuss the implications of extensive gene flow between magpie populations in sympatry with cuckoos for the population dynamics of hosts, in particular for the occurrence of egg rejection behavior in host populations and how the different rates of migration for both species can affect the dynamics of coevolutionary processes.

MAGPIE HOST MANIPULATION BY GREAT SPOTTED CUCKOOS: EVIDENCE FOR AN AVIAN MAFIA?

Why should the hosts of brood parasites accept and raise parasitic offspring that differ dramatically in appearance from their own? There are two solutions to this evolutionary enigma. (1) Hosts may not yet have evolved the capability to discriminate against the parasite, or (2) parasite-host systems have reached an evolutionary equilibrium. Avian brood parasites may either gain renesting opportunities or force their hosts to raise parasitic offspring by destroying or preying upon host eggs or nestlings following host ejection of parasite offspring. These hypotheses may explain why hosts do not remove parasite offspring because only then will hosts avoid clutch destruction by the cuckoo. Here we show experimentally that if the egg of the parasitic great spotted cuckoo Clamator glandarius is removed from nests of its magpie Pica pica host, nests suffer significantly higher predation rates than control nests in which parasite eggs have not been removed. Using plasticine model eggs resembling those of magpies and observations of parasites, we also confirm that great spotted cuckoos that have laid an ejected egg are indeed responsible for destruction of magpie nests with experimentally ejected parasite eggs. Cuckoos benefit from destroying host offspring because they thereby induce some magpies to renest and subsequently accept a cuckoo egg.

Polymorphisms in the GNAS Gene as Predictors of Ventricular Tachyarrhythmias and Sudden Cardiac Death: Results From the DISCOVERY Trial and Oregon Sudden Unexpected Death Study

Background

Population‐based studies suggest that genetic factors contribute to sudden cardiac death (SCD).

Methods and Results

In the first part of the present study (Diagnostic Data Influence on Disease Management and Relation of Genetic Polymorphisms to Ventricular Tachy‐arrhythmia in ICD Patients [DISCOVERY] trial) Cox regression was done to determine if 7 single‐nucleotide polymorphisms (SNPs) in 3 genes coding G‐protein subunits (GNB3, GNAQ, GNAS) were associated with ventricular tachyarrhythmia (VT) in 1145 patients receiving an implantable cardioverter‐defibrillator (ICD). In the second part of the study, SNPs significantly associated with VT were further investigated in 1335 subjects from the Oregon SUDS, a community‐based study analyzing causes of SCD. In the DISCOVERY trial, genotypes of 2 SNPs in the GNAS gene were nominally significant in the prospective screening and significantly associated with VT when viewed as recessive traits in post hoc analyses (TT vs CC/CT in c.393C>T: HR 1.42 [CI 1.11‐1.80], P=0.005; TT vs CC/CT in c.2273C>T: HR 1.57 [CI 1.18‐2.09], P=0.002). TT genotype in either SNP was associated with a HR of 1.58 (CI 1.26‐1.99) (P=0.0001). In the Oregon SUDS cohort significant evidence for association with SCD was observed for GNAS c.393C>T under the additive (P=0.039, OR=1.21 [CI 1.05‐1.45]) and recessive (P=0.01, OR=1.52 [CI 1.10‐2.13]) genetic models.

Conclusions

GNAS harbors 2 SNPs that were associated with an increased risk for VT in ICD patients, of which 1 was successfully replicated in a community‐based population of SCD cases. To the best of our knowledge, this is the first example of a gene variant identified by ICD VT monitoring as a surrogate parameter for SCD and also confirmed in the general population.

Clinical Trial Registration

URL: http://www.clinicaltrials.gov. Unique identifier: NCT00478933.

Electro-chemo-biomimetics from conducting polymers: fundamentals, materials, properties and devices

Conjugated conducting polymers, intrinsic conducting polymers or conducting polymers are complex and mixed materials; their electroactive fractions follow reversible oxidation/reduction reactions giving reversible volume variations to lodge or expel charge-balance counterions and osmotic-balance solvent molecules. The material content (reactive macromolecules, ions and water) mimics the dense intracellular matrix gel of living cells. Here the electropolymerization mechanism is reviewed highlighting the presence of parallel reactions resulting in electroactive and non-electroactive fractions of the final material. Conducting polymers are classified into nine different material families. Each of those families follows a prevalent reaction-driven exchange of anions or cations during oxidation/reduction (p-doping/p-dedoping or n-doping/n-dedoping). Polyaniline families also follow reaction-driven exchange of protons. The polymer/counterion composition changes for several orders of magnitude in a reversible way with the reversible reaction. The value of each of the different composition-dependent properties of the material also shifts in a reversible way driven by the reaction. Each property mimics another change in functional biological organs. A family of biomimetic devices is being developed based on each biomimetic property. Those electrochemical devices work driven by reactions of the constitutive material, as biological organs do. The simultaneous variation of several composition-dependent properties during the reaction announces an unparalleled technological world of multifunctional devices: several tools working simultaneously in one device. Such properties and devices are driven by electrochemical reactions: they are Faradaic devices and must be characterized by using electrochemical cells and electro-chemical methodologies.

Polymorphisms associated with ventricular tachyarrhythmias: rationale, design, and endpoints of the 'diagnostic data influence on disease management and relation of genomics to ventricular tachyarrhythmias in implantable cardioverter/defibrillator patients (DISCOVERY)' study

Implantable cardioverter-defibrillator (ICD) therapy is effective in primary and secondary prevention for patients who are at high risk of sudden cardiac death. However, the current risk stratification of patients who may benefit from this therapy is unsatisfactory. Single nucleotide polymorphisms (SNPs) are DNA sequence variations occurring when a single nucleotide in the genome differs among members of a species. A novel concept has emerged being that these common genetic variations might modify the susceptibility of a certain population to specific diseases. Thus, genetic factors may also modulate the risk for arrhythmias and sudden cardiac death, and identification of common variants could help to better identify patients at risk. The DISCOVERY study is an interventional, longitudinal, prospective, multi-centre diagnostic study that will enrol 1287 patients in approximately 80 European centres. In the genetic part of the DISCOVERY study, candidate gene polymorphisms involved in coding of the G-protein subunits will be correlated with the occurrence of ventricular arrhythmias in patients receiving an ICD for primary prevention. Furthermore, in order to search for additional sequence variants contributing to ventricular arrhythmias, a genome-wide association study will be conducted if sufficient a priori evidence can be gathered. In the second part of the study, associations of SNPs with ventricular arrhythmias will be sought and a search for potential new biological arrhythmic pathways will be investigated. As it is a diagnostic study, DISCOVERY will also investigate the impact of long-term device diagnostic data on the management of patients suffering from chronic cardiac disease as well as medical decisions made regarding their treatment.

Effects of Pretreatment with Intravenous Flecainide on Efficacy of External Cardioversion of Persistent Atrial Fibrillation

Electrical cardioversion is the most effective and safe method to restore sinus rhythm in patients with persistent AF. However, at least 25% of electrical cardioversions are unsuccessful. The aim of the present study was to evaluate, in a prospective, randomized and double-blind study, the efficacy of a pretreatment with intravenous flecainide in patients who underwent electrical cardioversion. Fifty-four consecutive patients with persistent AF, mean arrhythmia duration 8 (mean 3-18) weeks, were randomized in two groups. In the first group (n = 26), patients received flecainide (2 mg/kg as a 30-minute IV infusion) before electrical cardioversion. In the second group (n = 28), 100 mL IV infusion of 5% glucose was administered 30 minutes before electrical cardioversion. The study evaluated the (1). acute efficacy of electrical cardioversion, (2). mean and maximal energy required, (3). mean number of shocks needed, and (4). incidence of complications. The two groups were similar in terms of age, sex, mean AF duration, left ventricular systolic function, atrial dimension, and cardiovascular risk factors. Seventy-seven percent of patients recovered sinus rhythm with electrical cardioversion. No statistical difference was noted between the two groups: flecainide 19/26 (73%) versus placebo 23/28 (82%). No significant differences were found concerning mean or maximal energy and number of shocks required. No major complications were observed. After a 30-day follow-up, 54% of patients maintained sinus rhythm with no difference between the two groups. Pretreatment with intravenous flecainide before electrical cardioversion is not useful in reducing technical failure of cardioversion, however, flecainide does not diminish the effectiveness of electrical cardioversion.

Single-lead VDD-pacing system incorporating high impedance stimulation: a multicentre study

AIM

The purpose of this study was to evaluate the performance of a new VDD pacing system incorporating a high impedance, single-pass VDD lead. The new lead is a bipolar, steroid-eluting, high impedance lead with a full-ring atrial dipole.

METHODS AND RESULTS

The system was implanted in 46 patients with high degree atrioventricular (AV) block. Patients were followed at pre-discharge, 6 weeks, and 3 months. The mean measured P-wave amplitude was stable, with values between 1.18 and 1.43 mV. Atrial sensing was reliable during short-term evaluation at rest and in the sitting position, with AV-synchronous stimulation between 98.79 +/- 6.90% and 99.73 +/- 1.47%. Holter recordings after 6 weeks demonstrated AV-synchronous stimulation in 99.57 1.03% of all P-waves. Lead impedance was stable during follow-up, with mean values between 1000 and 1167 Q. Mean ventricular pacing thresholds (at 0.5 ms) were 0.47 V at implant, 0.49 V at pre-discharge, 0.74 V at 6 weeks, and 0.72 V at 3 months. R-wave amplitude remained stable between 14.9 and 16.7 mV during follow-up.

CONCLUSION

This new single-pass VDD lead system provided reliable atrial sensing and stable high impedance stimulation during a 3-month follow-up period.

The fate of the oxidizing tyrosyl radical in the presence of glutathione and ascorbate. Implications for the radical sink hypothesis

Cellular systems contain as much as millimolar concentrations of both ascorbate and GSH, although the GSH concentration is often 10-fold that of ascorbate. It has been proposed that GSH and superoxide dismutase (SOD) act in a concerted effort to eliminate biologically generated radicals. The tyrosyl radical (Tyr.) generated by horseradish peroxidase in the presence of hydrogen peroxide can react with GSH to form the glutathione thiyl radical (GS.). GS. can react with the glutathione anion (GS-) to form the disulfide radical anion (GSSG-). This highly reactive disulfide radical anion will reduce molecular oxygen, forming superoxide and glutathione disulfide (GSSG). In a concerted effort, SOD will catalyze the dismutation of superoxide, resulting in the elimination of the radical. The physiological relevance of this GSH/SOD concerted effort is questionable. In a tyrosyl radical-generating system containing ascorbate (100 microM) and GSH (8 mM), the ascorbate nearly eliminated oxygen consumption and diminished GS. formation. In the presence of ascorbate, the tyrosyl radical will oxidize ascorbate to form the ascorbate radical. When measuring the ascorbate radical directly using fast-flow electron spin resonance, only minor changes in the ascorbate radical electron spin resonance signal intensity occurred in the presence of GSH. These results indicate that in the presence of physiological concentrations of ascorbate and GSH, GSH is not involved in the detoxification pathway of oxidizing free radicals formed by peroxidases.

Great spotted cuckoos improve their reproductive success by damaging magpie host eggs

Adult great spotted cuckoos, Clamator glandariusdamage the eggs of their magpie, Pica picahost without removing or eating them. The number of damaged magpie eggs was recorded in 360 parasitized nests of which 62.2% contained between one and eight damaged magpie eggs. Egg-destroying behaviour may be adaptive if it reduces nestling competition and/or enhances the hatching success of the cuckoo. To clarify the role of egg destruction for the reproductive success of great spotted cuckoos, unparasitized magpie nests were experimentally parasitized (without egg damage) by introducing cuckoo eggs or chicks. Egg damage was common in parasitized nests but the eggs were not damaged by the hosts. Egg damage increased the breeding success of the cuckoos, by both reducing the number of competing host chicks in the nest and increasing the likelihood that late-laid cuckoo eggs would hatch.Copyright 1997 The Association for the Study of Animal Behaviour1997The Association for the Study of Animal Behaviour

Re-examining repeated testing and teacher effects in a remedial mathematics course

This study examined the impact of repeated testing and teachers' effects on student achievement in a remedial mathematics course. A 2 x 2 completely randomised factorial design was used, with final examination performance the dependent variable and testing attempts and the teacher factor the independent variables. The study found no main effects for teacher but a main effect for testing attempts and a teacher-factor/testing-attempt interaction. Post hoc findings qualified a direct interpretation of the main effect. The implications for further research and application are discussed, giving special attention to teacher effects, the needs of remedial mathematics instruction, and the claims of mastery-learning pedagogies.

The effect of isoxicam on neutrophil and monocyte function

1 Isoxicam was found to inhibit monocyte and neutrophil cell chemotaxis at therapeutic concentrations. 2 The effect was observed after in vitro incubation of normal cells and in vivo in patients with rheumatoid arthritis. 3 Compared to other NSAIDs studied in our laboratory, isoxicam was shown to have a broader spectrum of inhibitory action on the cells involved in the chronic inflammation associated with rheumatoid arthritis.