Dubious effect of the high biventricular paced beats percentage itself on the cardiac resynchronization efficacy in patients with atrial fibrillation. The randomized Pilot-CRAfT Study results

Funding Acknowledgements

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): National Institute of Cardiology statutory grant

Background

The presence of atrial fibrillation (AF) in cardiac resynchronization therapy (CRT) recipients is common and AF is a marker of poorer CRT response. The negative influence of AF on CRT efficacy is belived to be mediated mainly by the drop of effectively captured biventricular paced beats percentage (BiVp%). According to observational trials, the minimal BiVp associated with better outcomes is 95-98%, however there is lack of randomized trials to confirm this findings.

Purpose

The purpose of the study was to assess the influence of BiVp% itself on the clinical outcomes in the population CRT patients with atrial fibrillation in a prospective, randomized cohort.

Methods

The study included the prospective Pilot-CRAfT study participants that is patients with CRT and permanent or persistent AF lasting for ≥6 months that were randomly assigned to rhythm or rate control strategy. We divided the whole study population according to their BiVp at the 12 month follow-up with two borderline BiVp values (BiVp >98% vs <98% and >95% vs <95%) and analysed the echocardiographic indices, exercise tolerance and quality of life between the prespecified groups.

Results

The study included 43 CRT patients (97,7% males) aged 68,4 (SD: ±8,3) years with mean BiVp% 82,4% ±9,7% at baseline. The mean baseline left ventricular ejection fraction (LVEF), left ventricular end diastolic diameter (LVEDD) and maximal oxygen uptake (VO2max) were: 30 ±8%, 65 ±8 mm, 14 ±5 mL/(kg*min), respectively. In both of the study arms the BiVp% raised significantly reaching 98,1 ±2,3% and 96,3 ±3,9% in the rhythm control and the rate control arms respectively (P=0,093). As a result the were overall 21 patients with BiVp >98% and 29 patients with BiVp >95% at the end of the study. The BiVp groups >98% vs <98% and >95% vs <95% did not differ as to baseline characteristics and we have not observed any differences in the mean LVEF, mean LVEDD, mean VO2max, and quality of life in the prespecified BiVp% groups at the end of the follow up. Moreover no linear correlations between the BiVp% and LVEF, LVEDD, VO2max values were observed. However, in the rate control group patients with AVNA performed had lower LVEDD at the end of the study (57,7 ±3,0 vs 65,4 ±7,0 p=0,007) and significant decrease in the LVEDD after AVNA was observed (-8,6 95%CI [-14,9; -2,3]).

Conclusions

The BiVp >98% or >95% alone does not seem to warrant good response to cardiac resynchronization in patients with persistent atrial fibrillation as assessed in the prospective randomized cohort. However, performing AVNA in this group of patients may be beneficial in terms of LVEDD decrease.

Rhythm or rate control strategy in CRT recipients with long-standing persistent atrial fibrillation - preliminary results of the PilotCRAfT study

Funding Acknowledgements

Type of funding sources: Public Institution(s). Main funding source(s): National Institute of Cardiology in Warsaw Statutory Grant

Background

The presence of atrial fibrillation (AF) in cardiac resynchronization therapy (CRT) recipients is common and AF is a marker of poorer CRT response. The negative influence of AF on CRT efficacy is mediated mainly by the drop of the effectively captured biventricular paced beats percentage (BiVp%) which should exceed 95-98% to warrant good CRT response.  Sinus rhythm (SR) restoration may improve CRT efficacy which in turn may protect AF recurrence. However, there is lack of randomized studies comparing rhythm and rate control strategies in these patients.

Purpose

The purpose of the Pilot-CRAfT study (NCT01850277) was to compare the efficacy of rhythm vs rate control strategy in CRT patients with long-standing persistent or permanent atrial fibrillation.

Methods

The study included patients with CRT and permanent or persistent AF lasting for ≥6 months, resulting in BiVp% <95%, who were randomly assigned to rhythm or rate control strategy. The rhythm control strategy comprised of external electrical cardioversion (EEC). The rate control strategy included pharmacotherapy and atrioventricular node ablation (AVNA) as needed. Both of the study arms received amiodarone. The follow-up lasted 12 months. The primary endpoint was the 12-month BiVp%. The patients underwent ECHO, cardiopulmonary test, quality of live (QoL) and clinical outcomes assessment.  

Results

The study included 43 CRT patients (97,7% males) aged 68,4 (SD: ±8,3) years with mean BiVp% 82,4% ±9,7% at baseline. The mean duration of AF paroxysm was 25 ±19 months. The mean baseline left ventricular ejection fraction (LVEF), left atrium area and maximal oxygen uptake (VO2max) were: 30 ±8%, 33 ±7 cm2, 14 ±5 mL/(kg*min), respectively. The EEC was performed in 19 out of 22 patients assigned to the rhythm control arm. The immediate success rate of EEC was 58%. 42% of  the rhythm control arm patients remained in SR after 12 months. In the rate control group 1 person underwent AVNA and in 1 patient spontaneous SR resumption was observed. After 12 months there was significant BiVp% increase in both the rhythm and the rate control arms (98,1 ±2,3 vs 96,3 ±3,9%, respectively. The BiVp% differences between the groups were not significant (P = 0,093). However, in the per protocol analysis, the rhythm control group had greater LVEF after 12 months as opposed to the rate control arm (36,8% vs 29,9% respectively, P = 0,039). The LVEF raised significantly in the rhythm control group (ΔLVEF 5,0 (95%CI: 1,54; 8,46)). No significant differences between the groups in the VO2max, QoL, clinical and safety end-points were noticed.

Conclusions

Structured follow-up of CRT patients with long-standing persistent or permanent AF leads to significant BiVp% increase exceeding 95%. The rate control strategy did not improve CRT effectivness, irrespective of high BiVp%. However limited in the efficacy, the rhythm control strategy may improve CRT outcome in these patients, resulting in LVEF increase.

P429The efficacy of electrical cardioversion of long-standing persistent or permanent atrial fibrillation in cardiac resynchronization therapy recipients

Funding Acknowledgements

Institute of Cardiology statutory grant (grant no.: 2.30/VII/13)

Background

Atrial fibrillation (AF) and heart failure (HF) often co-exist and influence each other. The presence of AF is often regarded as a marker of HF severity.  Moreover, AF in cardiac resynchronization therapy (CRT) recipients hinders the CRT effectiveness in HF treatment by the reduction of the percentage of biventricular paced beats (BiVp%). Sinus rhythm (SR) restoration makes CRT more effective in HF treatment which may protect AF recurrence.

Purpose

To establish the effectiveness of electrical external cardioversion (EEC) in CRT patients with long-standing persistent AF or permanent, pre-treated with amiodarone.

Methods

The population of the study comprised of the Pilot-CRAfT study participants (NCT01850277), that is patients with CRT, long-standing persistent or considered as permanent AF and BiVp ≤ 95% who were randomly assigned to the "rhythm control" or the "rate control" strategy. The inclusion criteria included an AF paroxysm lasting at least 6 months. Both treatment arms received amiodarone beginning with the loading dose. Subsequently, patients assigned to the rhythm control strategy underwent electrical cardioversion. Rate control strategy included pharmacotherapy and atrioventricular node ablation, as needed. The follow up visit was performed 3 months after the enrolment visit. The EEC effectiveness, an AF recurrence within the 3 month period, BiVp% changes, the EEC parameters  and the EEC related complications were analysed.

Results

Out of 48 participants enrolled in the Pilot-CRAfT study, 25 patients were assigned to the rhythm control arm. The mean age of the rhythm control arm patients was 69,5 years , the mean left ventricular ejection fraction was 30,6% , the mean left atrium diameter was 53 mm and the median duration of persistent AF was 16 months. SR was obtained in 12 out of 20 (60%) patients who underwent the EEC . On the 3 month visit 8 patients remained in SR (40%). In patients with an AF paroxysm lasting less than 1 year the success rate was 100% vs 50% in the AF lasting 1 year at least (p = 0,11 ). After 3 months, SR remained in 100% vs 25% of patients, respectively (p =0,015.).  The effectiveness of anterior-posterior EEC electrodes placement was 20% and it was 71% for the anterior-lateral patch location . The EEC resulted in significant BiVp% rise - also in the whole intention-to-treat (ITT) group:  88,58%  before the EEC vs 96,68% after the EEC  (p = 0,002). No severe adverse events of the EEC were observed.

Conclusions

The electrical cardioversion of persistent atrial fibrillation lasting more than 6 months in patients with severe HF and treated with CRT is characterised by modest success rate, even after the amiodarone pre-treatment. However, the ECC ensures significant rise in BiVp% close to 97%, even in the whole EEC group based on the ITT principle. The AF paroxysm duration <1 year and the anterior-posterior patch placement may ensure better EEC efficacy in this group of patients.

P990Assessment of clinical risk factors for all-cause mortality among hypertrophic cardiomyopathy patients with ICDs

Introduction

According to the literature, the annual mortality rate of hypertrophic cardiomyopathy (HCM) patients is estimated to 1–2%. Sudden cardiac death (SCD), heart failure and thromboembolism are the main causes of death among this population. Patients at high risk for SCD, identified using HCM risk score, are qualified for ICD implantation. Unfortunately for clinicians, there is no validated model or statistical tool for assessment of the risk of mortality within the HCM patients with ICDs.

Purpose

The aim of this study was to determine the main risk factors of all- cause mortality in HCM patients with ICDs.

Methods

The long-term follow-up of group of 104 consecutive patients with HCM, who had the ICD implanted between 1996 and 2006 in tertiary reference clinical unit was performed. Twenty patients who died during observation were the subject of the current analysis. ICD was implanted for primary (n=16) and secondary (n=4) prevention of SCD within this subpopulation. Analysis were performed for mentioned below potential risk factors: age at the time of implantation, syncopes, family history of SCD, atrial fibrillation/supraventricular tachycardia, decreased left ventricular ejection fraction (LVEF), non-sustained ventricular tachycardia (nsVT), maximum left ventricular wall thickness, abnormal exercise blood pressure response, left ventricular outflow tract obstruction.

Results

The average time of survival since ICD implantation was 8,5±4,6 years. Decreased LVEF (Wald chi2 4,57; p=0,033), secondary prevention (Wald chi2 8,57; p=0,003), family history of SCD (Wald chi2 4,93; p=0,026) and episodes of nsVT (Wald chi2 3,49; p=0,062) are the clinical risk factors that significantly affect the time of survival. The probability of death, expressed as Hazard Ratio, was 27-fold higher in secondary prevention group (HR=27,18), almost 10-fold higher in patients with positive family history of SCD (HR=9,74) and 3,7-fold higher when nsVT was detected. The cause of death was established in 16/20 patients. In 15 cases, these were deaths from cardiovascular causes: end-stage heart failure (8), complications of heart transplantation or circulatory support (4), SCD (1) and other cardiovascular (2).

Conclusion

Secondary prevention, positive family history of SCD, nsVT and decreased LVEF seem to be the most significant risk factors associated with all- cause mortality in HCM patients with ICDs. Despite the ICD implantation, subpopulation studied had poor prognosis with high incidence of progression to end-stage heart failure. Further studies to create validated model for assessment of death risk in long-term observation of patients with HCM after ICD implantation are required.

Extracellular proteinases of Candida species pathogenic yeasts

The increased incidence of severe disseminated infections caused by the opportunistic yeast-like fungi Candida spp. highlights the urgent need for research into the major virulence factors of these pathogens-extracellular aspartic proteinases of the candidapepsin and yapsin families. Classically, these enzymes were considered to be generally destructive factors that damage host tissues and provide nutrients for pathogen propagation. However, in recent decades, novel and more specific functions have been suggested for extracellular candidal proteinases. These include contributions to cell wall maintenance and remodeling, the formation of polymicrobial biofilms, adhesion to external protective barriers of the host, the deregulation of host proteolytic cascades (such as the complement system, blood coagulation and the kallikrein-kinin system), a dysregulated host proteinase-inhibitor balance, the inactivation of host antimicrobial peptides, evasion of immune responses and the induction of inflammatory mediator release from host cells. Only a few of these activities recognized in Candida albicans candidapepsins have been also confirmed in other Candida species, and characterization of Candida glabrata yapsins remains limited.

Absence of bioactivity of lipid derivatives of serotonin

BACKGROUND

Serotonin (5-HT) and its receptors are present in central, the brain stem, and peripheral, the carotid body, tissues controlling the ventilatory responses to hypoxia. The exact action of serotonin and its nature are, however, unsettled. We hypothesized that the discrepant results on the ventilatory action of serotonin could be caused by the inability of serotonin to penetrate into the brain or the plasma membrane lipid bilayers, the target site of signal transduction cascades, after its exogenous administration.

OBJECTIVE

To study the penetrability of novel lipid derivatives of serotonin of varying fatty acid chain length and number of saturated/unsaturated bonds, the oleic, caprylic, and caprolic amides of 5-HT, into the brain, and their functional effects on the hypoxic ventilatory response in awake rats after systemic administration.

MATERIAL AND METHODS

Adult Wistar rats were used for the experiments. In the biochemical part of the study, the presence and stability of the compounds tested, after i.p. injection, was assessed in brain extracts using spectrophotometry and thin-layered chromatography. In the functional part, the ventilatory responses to 8 and 12% hypoxia were compared before and 1 h after the compound administration using a whole body plethysmography.

RESULTS

The "lipidized" serotonin compounds turned out to be stable in brain extracts in vitro for up to 3 h of the test. However, we could not substantiate the presence of any of the compounds in the brain, with either method used, after i.p. administration. Likewise, none of the compounds had any appreciable effect on the profile of the stimulatory hypoxic ventilatory response.

CONCLUSIONS

Synthetically attaching lipophilic groups to the serotonin molecule does not make it penetrate into the brain. The lack of serotonin penetrability likely depends on the planarity of its molecule, as it does not seem to depend on the size, number of carbons or bond saturation of the "lipidized" molecules. Such molecules do not directly interfere with the carotid chemoreceptor-mediated hypoxic ventilatory response. The study failed to substantiate the bioactive potential of the lipid derivatives of serotonin.

N-oleoyl-dopamine increases locomotor activity in the rat

N-oleoyl-dopamine (OLDA), a condensation product of oleic acid and dopamine (DA), is a bioactive lipid whose biological functions are not yet fully explored. The compound crosses the blood-brain barrier and might be considered as a carrier of DA into the brain. In this study we sought to determine whether OLDA would influence locomotor behavior and whether the central DA system would be involved in such influence. We addressed this issue by investigating horizontal locomotor activity in male Wistar rats after intraperitoneal administration of OLDA, 5-20 mg/kg, before and after pre-treatment with haloperidol, a D2 receptor antagonist. We found that OLDA caused a prompt stimulation of locomotor activity, with a bell-shaped dose-response. The maximum stimulatory effect was observed after 10 mg/kg of OLDA where the mean distance traveled by rats during a 2-hour test increased to 1213+/-196(SE) cm from the 403+/-89 cm in the vehicle-treated rats (P<0.05). This effect was dose-dependently antagonized by haloperidol (0.1-0.2 mg/kg). The results support the hypothesis that the OLDA-induced hyperlocomotion was mediated by the stimulation of DA systems. Using in vitro assays, we further demonstrated that OLDA is a stable compound that resists hydrolysis over a 2-hour period and thus the integral OLDA compound exerted DA-like effects. We conclude that OLDA is a potential brain modifier of motor behavior, the biological consequences of which remain to be explored.

Membrane association of N-oleoyl-dopamine in rat brain

N-oleoyl-dopamine (OLDA) belongs to a novel class of bioactive amides of fatty acids. The compound, a lipid derivative of dopamine, holds promise as a potential prodrug or carrier of dopamine into the brain. In this context, a key issue concerning OLDA is the integrity of the compound once it enters the brain. We addressed this issue in the current study by assessing the propensity of OLDA for hydrolysis in rat brain tissue in vitro. The brains were dissected from surgically anesthetized rats after they had been sacrificed by perfusion with physiological saline through the heart. Membrane fractions of brain tissue were isolated and incubated with 1 mmol/l OLDA. Stability of the OLDA molecule was assessed from the spectrophotometric recordings of OLDA spectra in membrane fractions at hourly time points for up to 24 hours. The methodological assumption was that any major change in the shape of the OLDA spectrum would point to a structural, and thus also possibly functional, alteration of the molecule. We found that the OLDA spectrum remained unchanged in the assays for up to 17 h of incubation. We conclude that OLDA strongly resists hydrolysis in brain membrane fractions. The results suggest that dopamine-like biological effects of OLDA might have to do with the interaction of the integral OLDA compound, rather than a dissociated-off dopamine moiety, with the dopaminergic system.

Respiratory responses to sudden pressure venting during stop consonant production

Twenty healthy adults, age range 20-55 years, participated in a study to assess the responses of the upper airway to sudden, unanticipated pressure venting during speech production. A computer was used to open or close a valve in a random fashion during one of two productions of the word 'hamper'. The SAR System (Microtronics Corp., Chapel Hill, N.C., USA) was used to collect and monitor respiratory variables associated with speech production. Results indicated no significant changes in duration between vented and unvented conditions. Although intraoral pressure was reduced under vented conditions, the magnitude was sufficient for sound generation. Respiratory effort increased when the airway was suddenly vented, suggesting a compensatory response to experimental perturbation. However, the response contrasted somewhat from what has been observed in patients with velopharyngeal inadequacy, indicating that the strategy used may be different.

Avidity maturation of antibody to Haemophilus influenzae type b (Hib) after immunization with diphtheria-tetanus-acellular pertussis-hib-hepatitis B combined vaccine in infants

Antibody avidity to Haemophilus influenzae type b (Hib) polysaccharide (PS) was assessed in infants vaccinated with diphtheria-tetanus-acellular pertussis (DTaP) combined with Hib-PS conjugated to tetanus toxoid (PRP-T) and hepatitis B (HB) (DTaP-PRP-T-HB) and after a PRP-conjugate (CRM197-OS) booster 3-7 months later. Avidity differed between infants with anti-Hib-PS IgG antibody <1 or >1 microg/mL postprimary series (avidity index [AI], 42%, 95% confidence interval [CI], 35%-49%, and 68% and 63%-72%, respectively; P<.0001). For infants with <1 microgram/mL anti-Hib-PS IgG antibody, mean AI rose by the time of preboost immunization to 61% (95% CI, 57%-65%), even though total IgG antibody levels fell. Spontaneous Hib-PS antibody rises after primary series DTaP-PRP-T-HB vaccination were followed by high postboost anti-Hib-PS IgG antibody levels and avidity. The DTaP-PRP-T-HB combination vaccine studied elicits high avidity antibody, and affinity maturation appears to occur in the absence of further antigen exposure even in those with very low anti-Hib-PS antibody.