Influence of obesity and overweight on the association between sleep-disordered breathing and atrial fibrillation: the DASAP-HF study

Background

The association between sleep apnea (SA) and atrial fibrillation (AF) has been well described. However, it remains unclear whether the association is causative or primarily dependent on shared comorbidities such as obesity. The Respiratory Disturbance Index (RDI) computed by an implantable cardioverter defibrillator (ICD) algorithm accurately identifies severe SA, whether central or obstructive in origin.

Purpose

In the present analysis we studied in patients with heart failure the contribution of obesity in the relationship between SA, measured by RDI, and AF.

Methods

Patients with ejection fraction ≤35% implanted with an ICD endowed with an algorithm (ApneaScan) that calculates the RDI each night, were enrolled and followed-up for 24 months. The weekly mean RDI value was considered, as calculated during the entire follow-up period. The endpoint was daily AF burden of ≥6 hours.

Results

164 patients (age 67±10 years, 75% male, ejection fraction 29±5%) had usable RDI values during the entire follow-up period. Body mass index (BMI) was <25 kg/m2 in 62 patients (normal), 25.0–29.9 kg/m2 in 66 patients (overweight), ≥ 30 kg/m2 in 36 patients (obese). When compared with normal patients (31±11 episodes/h), the average RDI value calculated during the entire follow-up period did not differ in overweight patients (35±13 episodes/h, p=0.114), but was significantly higher in obese patients (39±12 episodes/h, p=0.002). During follow-up, AF burden ≥6 hours/day was documented in 48 (29%) patients (BMI ≥ versus <25 kg/m2; HR: 1.47, 95% CI: 0.83–2.60, p=0.197; BMI ≥ versus <30 kg/m2; HR: 0.98, 95% CI: 0.46–2.09, p=0.963). Based on the ROC curve analysis, average RDI ≥37 episodes/h maximized sensitivity and specificity for the prediction of AF (Area under the curve: 0.63, 95% CI: 0.55–0.70, p=0.011). Device-detected RDI ≥37 episodes/h was associated with the occurrence of AF on univariate analysis (HR: 3.88, 95% CI: 2.02–7.44, p<0.001), as well as after correction for either BMI ≥25 kg/m2 (HR: 3.76, 95% CI: 1.94–7.26, p<0.001), or BMI ≥30 kg/m2 (HR: 4.15, 95% CI: 2.15–8.04, p<0.001).

Conclusions

In heart failure patients, we confirmed the association between ICD-detected SA and AF, an association that persisted independent of patient body habitus.

Funding Acknowledgement

Type of funding sources: Private grant(s) and/or Sponsorship. Main funding source(s): The study is supported by a research grant from Boston Scientific

Personalized assessment of the cumulative complication risk of the atrial fibrillation ablation track: The AF-TRACK calculator

Background

Atrial fibrillation (AF) ablation strategy is associated with a non-negligible risk of complications and often requires repeat procedures (AF ablation track), implying repetitive exposure to procedural risk.

Objective

The purpose of this study was to develop and validate a model to estimate individualized cumulative risk of complications in patients undergoing the AF ablation track (Atrial Fibrillation TRAck Complication risK [AF-TRACK] calculator).

Methods

The model was derived from a multicenter cohort including 3762 AF ablation procedures in 2943 patients. A first regression model was fitted to predict the propensity for repeat ablation. The AF-TRACK calculator computed the risk of AF ablation track complications, considering the propensity for repeat ablation. Internal (cross-validation) and external (independent cohort) validation were assessed for discrimination capacity (area under the curve [AUC]) and goodness of fit (Hosmer-Lemeshow [HL] test).

Results

Complications (N = 111) occurred in 3.7% of patients (2.9% of procedures). Predictors included female sex, heart failure, sleep apnea syndrome, and repeat procedures. The model showed fair discrimination capacity to predict complications (AUC 0.61 [0.55-0.67]) and likelihood of repeat procedure (AUC 0.62 [0.60-0.64]), with good calibration (HL χ² 12.5; P = .13). The model maintained adequate discrimination capacity (AUC 0.67 [0.57-0.77]) and calibration (HL χ² 5.6; P = .23) in the external validation cohort. The validated model was used to create the Web-based AF-TRACK calculator.

Conclusion

The proposed risk model provides individualized estimates of the cumulative risk of complications of undergoing the AF ablation track. The AF-TRACK calculator is a validated, easy-to-use, Web-based clinical tool to calibrate the risk-to-benefit ratio of this treatment strategy.

Association between implantable defibrillator-detected sleep apnea and atrial fibrillation: the DASAP-HF study

AIM

The Respiratory Disturbance Index (RDI) computed by an implantable cardioverter defibrillator (ICD) algorithm accurately identifies severe sleep apnea (SA). In the present analysis we tested the hypothesis that RDI could also predict AF burden.

METHODS

Patients with ejection fraction ≤35% implanted with an ICD were enrolled and followed-up for 24 months. One month after implantation, patients underwent a polysomnographic study. The weekly mean RDI value was considered, as calculated during the entire follow-up period and over a 1-week period preceding the sleep study. The endpoints were: daily AF burden of ≥5 minutes, ≥6 hours, ≥23 hours.

RESULTS

164 patients had usable RDI values during the entire follow-up period. Severe SA (RDI≥30 episodes/h) was diagnosed in 92 (56%) patients at the time of the sleep study. During follow-up, AF burden ≥5 minutes/day was documented in 70 (43%), ≥6 hours/day in 48 (29%), and ≥23 hours/day in 33 (20%) patients. Device-detected RDI≥30 episodes/h at the time of the polygraphy, as well as the polygraphy-measured apnea hypopnea index ≥30 episodes/h, were not associated with the occurrence of the endpoints, using a Cox regression model. However, using a time-dependent model, continuously measured weekly mean RDI≥30episodes/h was independently associated with AF burden ≥5 minutes/day (HR:2.13, 95%CI:1.24-3.65, p=0.006), ≥6 hours/day (HR:2.75, 95%CI:1.37-5.49, p=0.004), and ≥23 hours/day (HR:2.26, 95%CI:1.05-4.86, p=0.037).

CONCLUSIONS

In heart failure patients, ICD-diagnosed severe SA on follow-up data review identifies patients who are from two- to three-fold more likely to experience an AF episode, according to various thresholds of daily AF burden. This article is protected by copyright. All rights reserved.

Pharmacological Cardioversion after Pre-Treatment with Antiarrythmic Drugs Prior to Electrical Cardioversion in Persistent Atrial Fibrillation: Impact on Maintenance of Sinus Rhythm

BACKGROUND

Antiarrhythmic drugs (AADs) are frequently initiated in patients with persistent atrial fibrillation (AF) prior to electrical cardioversion (ECV), achieving pharmacological cardioversion (PCV) in some cases. Little is known about the mode of cardioversion and the effect of the type of AAD used in the maintenance of sinus rhythm (SR).

METHODS

From three national surveys of patients with persistent AF referred for ECV, we selected those who were pre-treated with AADs (amiodarone or group Ic AADs). We analyzed the effect of the type of cardioversion (pharmacological vs. electrical) and the AAD used in the maintenance of SR at three months.

RESULTS

Among the 665 patients selected, 151 had a successful PCV prior to the planned ECV. In the remaining 514 patients, 460 had a successful ECV. A successful PCV was related to a higher rate of SR maintenance than a successful ECV (77.9% vs. 57.5%; p < 0.0001). After a successful PCV, the maintenance of SR was identical in those patients treated with amiodarone and those treated with group Ic AADs (77.4% vs. 77.5%; p = 0.99), whereas after a successful ECV, amiodarone was clearly superior to group Ic AADs (61.3% vs. 43.0%; p = 0.001). Considering patients with successful PCV and ECV together, PCV was an independent factor related to the maintenance of SR.

CONCLUSIONS

In patients with persistent AF, successful PCV selects a subgroup with a high probability of maintenance of SR. With regard to drugs, amiodarone was superior to group Ic AADs in patients with ECV, whereas in PCV, no differences were observed.

Prognostic value of implantable defibrillator-computed respiratory disturbance index: The DASAP-HF study

BACKGROUND

Sleep apnea, as measured by polysomnography, is associated with adverse outcomes in heart failure. The DASAP-HF (Diagnosis and Treatment of Sleep Apnea in Patient With Heart Failure) study previously demonstrated that the respiratory disturbance index (RDI) computed by the ApneaScan algorithm (Boston Scientific) accurately identifies severe sleep apnea in implantable cardioverter-defibrillator (ICD) patients.

OBJECTIVE

The purpose of the long-term study phase was to assess the incidence of clinical events after 24 months and investigate the association with RDI values.

METHODS

Patients with left ventricular ejection fraction ≤35% implanted with an ICD were enrolled and followed-up for 24 months. The RDI calculated at 1 month after implantation was used to stratify patients (below or above 30 episodes/h). The endpoints were all-cause death and a combination of all-cause death or cardiovascular hospitalization.

RESULTS

Of the 265 enrolled patients, 224 had usable RDI values. Severe sleep apnea (RDI ≥30 episodes/h) was diagnosed in 115 patients (51%). These patients were more frequently male (84% vs 72%; P = .030) and had higher creatinine levels. During median follow-up of 25 months, 19 patients (8%) died. Cardiovascular hospitalizations were reported in 19 patients (8%). The risk of all-cause death was higher in patients with RDI ≥30 episodes/h (hazard ratio [HR] 3.33; 95% confidence interval [CI] 1.35-8.21; P = .023), as well as the risk of all-cause death or cardiovascular hospitalization (HR 1.94; 95% CI 1.01-3.76; P = .048). At multivariate analysis, independent predictors of death were RDI ≥30 episodes/h (HR 4.02; 95% CI 1.16-13.97; P = .029) and creatinine levels (HR 2.36; 95% CI 1.26-4.42; P = .008).

CONCLUSION

In heart failure patients implanted with an ICD, higher RDI values are associated with death and cardiovascular hospitalizations. Device-detected severe sleep apnea independently predicts death.

An "inappropriately appropriate" shock in a subcutaneous implantable cardioverter-defibrillator: The importance of the SMART pass algorithm

We report on a case of a 78-years-old patient with a subcutaneous implantable cardioverter defibrillator (S-ICD) and an episode of a sustained ventricular tachycardia (VT) at a rate slower than the programmed shock zone. Because of T-wave oversensing the device interpreted it as fast VT that triggered the delivery of an "inappropriately appropriate shock" that terminated it. The patient had again more VT episodes but after programming the SMART pass algorithm (previously programmed "OFF") the device showed no longer frequent T-wave oversensing and no additional inappropriate shocks occurred.

[Determining cardiac output by carbon dioxide rebreathing in patients with sleep apnea-hypopnea syndrome]

The objective of the present study was to determine the relation between resting cardiac output in patients with sleep apnea-hypopnea syndrome but without arterial hypertension or heart failure as measured indirectly by the carbon dioxide rebreathing method and left ventricular function evaluated by transthoracic echocardiography. We also compared the variability and reproducibility of the measurements obtained by the equilibrium and exponential methods. In patients with sleep apnea-hypopnea syndrome there was a modest but significant association between resting cardiac output and left ventricular shortening fraction (r=0.690; P<.001) and left ventricular ejection fraction (r=0.690; P<.001). In addition, mean (SD) cardiac output obtained by the equilibrium method showed a lower coefficient of variability (0.21 [0.08]) than that of the exponential method (0.16 [0.09]) (P<.01) as well as a narrower reproducibility interval.

Atrial fibrillation triggered by postinfarction ventricular premature beats in a patient with Wolff-Parkinson-White syndrome

The mechanism by which atrial fibrillation is initiated in patients with accessory pathways is not fully understood. Retrograde conduction of ventricular premature beats to the atrium, causing the arrhythmia, is a very rare cause. We report a patient with Wolff-Parkinson-White syndrome (WPW), without previous tachycardias, who presented multiple episodes of paroxysmal atrial fibrillation after having a myocardial infarction. During the electrophysiological (EP) study the patient presented two spontaneous episodes of atrial fibrillation initiated by ventricular premature beats conducted to the atria through the accessory pathway. After successful catheter ablation of the accessory pathway the patient did not present arrhythmia recurrences.

The effect of melatonin in patients with fibromyalgia: a pilot study

The aim of the study was to determine the possible effect of melatonin treatment on disturbed sleep, fatigue and pain symptoms observed in fibromyalgia (FM) patients. Twenty-one consecutive patients with FM were included in an open 4-week-duration pilot study. Before and after treatment with melatonin 3 mg at bedtime, patients were evaluated using tender point count by palpation of 18 classic anatomical regions, pain score in four predesignated areas, pain severity on a 10 cm visual analogue scale (VAS), sleep disturbances, fatigue, depression, anxiety, and patient and physician global assessments, also by a VAS. Urine 6-sulphatoxymelatonin levels (aMT-6S) were measured in the patients and 20 age- and sex-matched controls. Nineteen patients completed the study. One patient withdrew because of migraine and another was lost to follow-up. At day 30, median values for the tender point count and severity of pain at selected points, patient and physician global assessments and VAS for sleep significantly improved with melatonin treatment. Other variables improved but did not reach statistical significance. Adverse events were mild and transient. Lower levels of aMT-6S were found in FM patients compared with normal median controls (+/-SD, 9.16 +/- 7.9 microg/24 h vs 16.8 +/- 12.8 microg/24 h) (p = 0.06). Although this is an open study, our preliminary results suggest that melatonin can be an alternative and safe treatment for patients with FM. Double-blind placebo controlled studies are needed.

Cutting edge: human B cell function is regulated by interaction with soluble CD14: opposite effects on IgG1 and IgE production

The mechanism(s) controlling activation of naive B cells, their proliferation, Ag receptor affinity maturation, isotype switching, and their fate as memory or plasma cells is not fully elucidated. Here we show that between 24 and 60% of CD19+ cells in PBMC bind soluble CD14 (sCD14). Tonsillar B cells also bind sCD14, but preferentially the CD38-ve/low cells. Interaction of sCD14 with B cells resulted in higher levels of IgG1 and marked inhibition of IgE production by activated tonsillar B cells and Ag-stimulated PBMC. We found that sCD14 interfered with CD40 signaling in B cells, inhibited IL-6 production by activated B cells, and increased the kinetics and magnitude of CD40 ligand expression on T cells. Together with the previously reported effects on T cells, these findings define sCD14 as a novel soluble regulatory factor capable of modulating cellular and humoral immune responses by interacting directly with T and B cells.

Soluble CD14 acts as a negative regulator of human T cell activation and function

T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.

Soluble CD14 acts as a negative regulator of human T cell activation and function

T cell activation is controlled by the coordination of stimulatory and negative regulatory signals which are not completely defined. In this study we tested for a possible direct effect of CD14 on the regulation of T cell activation and function. We show that soluble CD14 (sCD14) induces inhibition of antigen-mediated peripheral blood mononuclear cells (PBMC) proliferation and anti-CD3-mediated proliferation of CD4+CD8+, CD4+CD8+ and CD4+CD8+ Tcell clones. This effect is not due to cell death, but results from a marked inhibition of IL-2 production. Proliferation of T cell clones due to exogenous IL-2 is not affected by sCD14. We also found that sCD14 inhibits production of another Th1-like cytokine, IFN-gamma and a Th2-like cytokine, IL-4. Importantly, sCD14 induces a progressive accumulation of the inhibitory protein IkappaB-alpha. We show that sCD14 binds to activated T cells. Following cell activation, biotinylated sCD14 stains CD3+ PBMC, as well as human T cell clones with varying intensity. The binding is saturable, can be inhibited by excess of unlabeled sCD14 and, following binding, sCD14 is internalized. Collectively, these findings reveal a previously unrecognized function of sCD14, namely its capacity to negatively regulate T lymphocyte activation and function by interacting directly with activated T cells.

Aeromonas hydrophila associated with a severe outbreak of infection in farmed rabbits

An outbreak of infection with a high rate of mortality has been detected in an industrial rabbitry in Spain. Aeromonas hydrophila was isolated in pure culture from liver, lung, heart and spleen of ill and moribund animals. All the isolates belonged to O:11 serogroup, autogglutinated after boiling, were resistant to the bactericidal action of the fresh rabbit serum and did not agglutinate in acriflavine. They were producers of hemolysins and proteases but were not enterotoxigenic.

Mice with the xid defect have helper cells for T15 idiotype-dominant anti-phosphorylcholine primary and secondary plaque-forming cells responses

We have examined the abilities of helper T cells from commercially available (CBA/N X BALB/c)F1 (NBF1) xid male and phenotypically normal female mice to help T15+ and T15- B cells to produce thymus-dependent phosphorylcholine (PC)-specific direct plaque-forming cell responses. Carrier-primed T cells from both male and female mice were found (a) to restore T15+ TD responses in congenitally athymic BALB/c mice, (b) to help PC-primed BALB/c splenic B cells produce predominantly T15+ responses, and (c) to provide help for T15+ and T15- PFC responses generated by PC-primed normal F1 splenic B cells. Furthermore, carrier-primed irradiated xid and normal recipients contributed adequate helper activity for T15 dominant responses. We therefore conclude that male and female NBF1 mice are equally capable of helping T15+ responses.