Atrial Fibrillation and Congestive Heart Failure: Risk Factors, Mechanisms, and Treatment

Device-detected atrial sensing amplitudes as a marker of increased risk for new onset and progression of atrial high-rate episodes

BACKGROUND

Atrial high-rate episodes (AHREs) are frequent in patients with cardiac implantable electronic devices. A decrease in device-detected P-wave amplitude may be an indicator of periods of increased risk of AHRE.

OBJECTIVE

The objective of this study was to assess the association between P-wave amplitude and AHRE incidence.

METHODS

Remote monitoring data from 2579 patients with no history of atrial fibrillation (23% pacemakers and 77% implantable cardioverter-defibrillators, of which 40% provided cardiac resynchronization therapy) were used to calculate the mean P-wave amplitude during 1 month after implantation. The association with AHRE incidence according to 4 strata of daily burden duration (≥15 minutes, ≥6 hours, ≥24 hours, ≥7 days) was investigated by adjusting the hazard ratio with the CHA2DS2-VASc score.

RESULTS

The adjusted hazard ratio for 1-mV lower mean P-wave amplitude during the first month increased from 1.10 (95% confidence interval [CI], 1.05-1.15; P < .001) to 1.18 (CI, 1.09-1.28; P < .001) with AHRE duration strata from ≥15 minutes to ≥7 days independent of the CHA2DS2-VASc score. Of 871 patients with AHREs, those with 1-month P-wave amplitude <2.45 mV had an adjusted hazard ratio of 1.51 (CI, 1.19-1.91; P = .001) for progression of AHREs from ≥15 minutes to ≥7 days compared with those with 1-month P-wave amplitude ≥2.45 mV. Device-detected P-wave amplitudes decreased linearly during the 1 year before the first AHRE by 7.3% (CI, 5.1%-9.5%; P < .001 vs patients without AHRE).

CONCLUSION

Device-detected P-wave amplitudes <2.45 mV were associated with an increased risk of AHRE onset and progression to persistent forms of AHRE independent of the patient's risk profile.

Towards Improved Human In Vitro Models for Cardiac Arrhythmia: Disease Mechanisms, Treatment, and Models of Atrial Fibrillation

Heart rhythm disorders, arrhythmias, place a huge economic burden on society and have a large impact on the quality of life of a vast number of people. Arrhythmias can have genetic causes but primarily arise from heart tissue remodeling during aging or heart disease. As current therapies do not address the causes of arrhythmias but only manage the symptoms, it is of paramount importance to generate innovative test models and platforms for gaining knowledge about the underlying disease mechanisms which are compatible with drug screening. In this review, we outline the most important features of atrial fibrillation (AFib), the most common cardiac arrhythmia. We will discuss the epidemiology, risk factors, underlying causes, and present therapies of AFib, as well as the shortcomings and opportunities of current models for cardiac arrhythmia, including animal models, in silico and in vitro models utilizing human pluripotent stem cell (hPSC)-derived cardiomyocytes.

Protocol of BEYOND trial: Clinical BEnefit of sodium-glucose cotransporter-2 (SGLT-2) inhibitors in rhYthm cONtrol of atrial fibrillation in patients with diabetes mellitus

SGLT-2 inhibitor, traditionally used for glycemic control, has several beneficial effects that can help manage heart failure (HF). SGLT-2 inhibitors reduce the risk of cardiovascular mortality in patients with HF. As atrial fibrillation (AF) is closely associated with HF and diabetes mellitus (DM) is a risk factor for AF, we assume that SGLT-2 inhibitors will also show therapeutic benefits regarding AF, especially for rhythm control. This trial has a multicenter, prospective, open, blinded endpoint design. It is a 1:1 randomized and controlled study. A total of 716 patients who are newly diagnosed of AF and DM within 1 year will be enrolled from 7 tertiary medical centers. The trial is designed to compare the effects of SGLT-2 inhibitors and other oral hypoglycemic agents on atrial rhythm control in patients with AF and DM. The primary outcome is the recurrence of AF within a year (including post-antiarrhythmic drugs (AAD) or ablation). The secondary outcomes are the ablation rate within a year, change in AF burden, size of the left atrium, NT-proBNP, the AF symptom score, and the quality of life. This trial will prospectively evaluate the effect and safety of SGLT-2 inhibitors on AF rhythm control in patients with DM. It will provide an invaluable dataset on rhythm control in AF with DM for future studies and offer novel information to assist in clinical decisions. (BEYOND trial, ClinicalTrials.gov number: NCT05029115. https://clinicaltrials.gov/ct2/show/NCT05029115).

Development and validation of a predictive model for new-onset atrial fibrillation in sepsis based on clinical risk factors

Objective

New-onset atrial fibrillation (NOAF) is a common complication and one of the primary causes of increased mortality in critically ill adults. Since early assessment of the risk of developing NOAF is difficult, it is critical to establish predictive tools to identify the risk of NOAF.

Methods

We retrospectively enrolled 1,568 septic patients treated at Wuhan Union Hospital (Wuhan, China) as a training cohort. For external validation of the model, 924 patients with sepsis were recruited as a validation cohort at the First Affiliated Hospital of Xinjiang Medical University (Urumqi, China). Least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression analyses were used to screen predictors. The area under the ROC curve (AUC), calibration curve, and decision curve were used to assess the value of the predictive model in NOAF.

Results

A total of 2,492 patients with sepsis (1,592 (63.88%) male; mean [SD] age, 59.47 [16.42] years) were enrolled in this study. Age (OR: 1.022, 1.009–1.035), international normalized ratio (OR: 1.837, 1.270–2.656), fibrinogen (OR: 1.535, 1.232–1.914), C-reaction protein (OR: 1.011, 1.008–1.014), sequential organ failure assessment score (OR: 1.306, 1.247–1.368), congestive heart failure (OR: 1.714, 1.126–2.608), and dopamine use (OR: 1.876, 1.227–2.874) were used as risk variables to develop the nomogram model. The AUCs of the nomogram model were 0.861 (95% CI, 0.830–0.892) and 0.845 (95% CI, 0.804–0.886) in the internal and external validation, respectively. The clinical prediction model showed excellent calibration and higher net clinical benefit. Moreover, the predictive performance of the model correlated with the severity of sepsis, with higher predictive performance for patients in septic shock than for other patients.

Conclusion

The nomogram model can be used as a reliable and simple predictive tool for the early identification of NOAF in patients with sepsis, which will provide practical information for individualized treatment decisions.

The Atrium in Atrial Fibrillation - A Clinical Review on How to Manage Atrial Fibrotic Substrates

Atrial fibrillation (AF) is the most common sustained arrhythmia in the population and is associated with a significant clinical and economic burden. Rigorous assessment of the presence and degree of an atrial arrhythmic substrate is essential for determining treatment options, predicting long-term success after catheter ablation, and as a substrate critical in the pathophysiology of atrial thrombogenesis. Catheter ablation of AF has developed into an essential rhythm-control strategy. Nowadays is one of the most common cardiac ablation procedures performed worldwide, with its success inversely related to the extent of atrial structural disease. Although atrial substrate evaluation remains complex, several diagnostic resources allow for a more comprehensive assessment and quantification of the extent of left atrial structural remodeling and the presence of atrial fibrosis. In this review, we summarize the current knowledge on the pathophysiology, etiology, and electrophysiological aspects of atrial substrates promoting the development of AF. We also describe the risk factors for its development and how to diagnose its presence using imaging, electrocardiograms, and electroanatomic voltage mapping. Finally, we discuss recent data regarding fibrosis biomarkers that could help diagnose atrial fibrotic substrates.

Tricarboxylic acid cycle related-metabolites and risk of atrial fibrillation and heart failure

BACKGROUND

Tricarboxylic acid (TCA) cycle deregulation may predispose to cardiovascular diseases, but the role of TCA cycle-related metabolites in the development of atrial fibrillation (AF) and heart failure (HF) remains unexplored. This study sought to investigate the association of TCA cycle-related metabolites with risk of AF and HF.

METHODS

We used two nested case-control studies within the PREDIMED study. During a mean follow-up for about 10 years, 512 AF and 334 HF incident cases matched by age (±5 years), sex and recruitment center to 616 controls and 433 controls, respectively, were included in this study. Baseline plasma levels of citrate, aconitate, isocitrate, succinate, malate and d/l-2-hydroxyglutarate were measured with liquid chromatography-tandem mass spectrometry. Multivariable conditional logistic regression models were fitted to estimate odds ratios (OR) and 95% confidence intervals (95% CI) for metabolites and the risk of AF or HF. Potential confounders included smoking, family history of premature coronary heart disease, physical activity, alcohol intake, body mass index, intervention groups, dyslipidemia, hypertension, type 2 diabetes and medication use.

RESULTS

Comparing extreme quartiles of metabolites, elevated levels of succinate, malate, citrate and d/l-2-hydroxyglutarate were associated with a higher risk of AF [ORQ4 vs. Q1 (95% CI): 1.80 (1.21-2.67), 2.13 (1.45-3.13), 1.87 (1.25-2.81) and 1.95 (1.31-2.90), respectively]. One SD increase in aconitate was directly associated with AF risk [OR (95% CI): 1.16 (1.01-1.34)]. The corresponding ORs (95% CI) for HF comparing extreme quartiles of malate, aconitate, isocitrate and d/l-2-hydroxyglutarate were 2.15 (1.29-3.56), 2.16 (1.25-3.72), 2.63 (1.56-4.44) and 1.82 (1.10-3.04), respectively. These associations were confirmed in an internal validation, except for aconitate and AF.

CONCLUSION

These findings underscore the potential role of the TCA cycle in the pathogenesis of cardiac outcomes.

Heart failure and atrial fibrillation: tachycardia-mediated acute decompensation

Aims

Tachycardia is a reversible event that may cause hemodynamic decompensation but may not necessarily cause direct damages to the myocardium. To evaluate the clinical outcomes of patients with heart failure (HF) and atrial fibrillation (AF), whose acute decompensation was tachycardia mediated.

Methods and results

The Korean Acute Heart Failure registry was a prospective registry that consecutively enrolled 5625 patients with acute HF. Patients were classified into three groups according to the rhythm and aggravating factor: (i) 3664 (65.1%) patients with sinus rhythm (SR), (ii) 1033 (18.4%) patients with AF whose decompensation was tachycardia‐mediated, AF‐TM (+), and (iii) N = 928 (16.5%) patients with AF whose decompensation was not tachycardia‐mediated, AF‐TM (−). The primary outcomes were in‐hospital and post‐discharge 1 year all‐cause mortality. At admission, the mean heart rate was 90.8 ± 23.4, 86.8 ± 26.8, and 106.3 ± 29.7 beats per minute for the SR, AF‐TM (−), and AF‐TM (+) groups, respectively. The AF‐TM (+) group had more favourable characteristics such as de novo onset HF, less diabetes, ischaemic heart disease, and higher blood pressure than the AF‐TM (−) group. In‐hospital mortality rates were 5.1%, 6.5%, and 1.7% for SR, AF‐TM (−), and AF‐TM (+) groups, respectively. In logistic regression analysis, the AF‐TM (+) group had lower in‐hospital mortality after adjusting the significant covariates (odds ratio, 0.49; 95% confidence interval, 0.26–0.93). The mortality rate did not differ between SR and AF‐TM (−) groups. During 1 year follow‐up, 990 (18.5%) patients died. In univariate and multivariate Cox proportional regression analyses, there was no difference in 1‐year all‐cause mortality between the three groups.

Conclusions

In patients with HF and AF, patients whose acute decompensation is tachycardia‐mediated have better in‐hospital, but similar post‐discharge outcomes compared with those with SR or those with AF whose decompensation is not tachycardia‐mediated.

Clinical Trial Registration: ClinicalTrial.gov NCT01389843.

Atrial Fibrillation–Mediated Cardiomyopathy

AF-mediated cardiomyopathy (AMC) is an important reversible cause of heart failure that is likely underdiagnosed in today’s clinical practice. AMC describes AF either as the sole cause for ventricular dysfunction or exacerbating ventricular dysfunction in patients with existing cardiomyopathy or heart failure. Studies suggest that irreversible ventricular and atrial remodeling can occur in AMC, making timely diagnosis and intervention critical to optimize clinical outcome. Clinical correlation between AF onset/burden and progression of cardiomyopathy/heart failure symptoms provides strong evidence for the diagnosis of AMC. Cardiac MRI, continuous cardiac monitoring, and biomarkers are important diagnostic tools. From the therapeutic standpoint, early data suggest that AF ablation may improve long-term outcomes in AMC patients compared with medical rate and rhythm control. Patients with more AF burden and less severe underlying structural heart disease are more likely to experience left ventricle function recovery with successful AF ablation. Despite recent advances, significant knowledge gaps exist in our understanding of the epidemiology, mechanisms, diagnosis, management strategies, and prognosis of AMC.

[Reverse remodelling of the heart after atrial fibrillation ablation in patients with heart failure with reduced ejection fraction]

AIM

To evaluate the effect of atrial fibrillation (AF) catheter ablation (CA) on long-term freedom from AF and left heart reverse remodeling in patients with heart failure with reduced ejection fraction (HFrEF).

METHODS

There were 47 patients (mean age 53.3 ± 10 years, 39 males) enrolled into single-center observational study, with left ventricular ejection fraction (LVEF) &lt;40 %. Patients underwent CA for AF refractory to antiarrhythmic drugs. Baseline clinical data and diagnostic tests results were obtained during personal visits and / or via secure telemedical services. Personal contact with evaluation of recurrence of AF and echocardiographic values was performed with 30 (64 %) patients.

RESULTS

Paroxysmal AF was present in 12 (40 %) patients, persistent - in 18 (60 %). During mean follow-up of 3 years (0.5-6 years) redo ablation was performed in 9 patients (30 %) with average number of 1.3 procedures per patient. At 6 months 24 (80 %) patients were free from AF, at last follow-up - 16 (53 %). The mean time to first recurrence following CA was 15.6±13.3 months. Follow-up echocardiography revealed significant LVEF improvement (р&lt;0,0001), reduction of left atrium size (р&lt;0,0001), left ventricle end-diastolic volume (р&lt;0,002) and left ventricle endsystolic volume (p&lt;0,0001) and mitral regurgitation (р=0,001).

CONCLUSION

AF CA in patients with HFrEF is associated with improvement in systolic function and left heart reverse remodeling. Durable long-term antiarrhythmic effect often requires repeated procedures.

N-terminal pro brain natriuretic peptide eliminates the prognostic effect of atrial fibrillation in patients with chronic heart failure

AIMS

Co-morbid atrial fibrillation (AF) increases both mortality and N-terminal pro brain natriuretic peptide (NT-proBNP) concentrations in patients with chronic heart failure (CHF). It is unclear whether AF worsens prognosis independently from NT-proBNP concentrations. If AF was an independent risk factor, NT-proBNP levels for outcome prediction would need to be adjusted in patients with AF. We aimed to analyse the influence of AF on the prognostic value of NT-proBNP in patients with CHF.

METHODS AND RESULTS

A total of 2541 consecutive CHF patients with sinus rhythm (SR) or AF were identified in the outpatients' CHF registry of the University of Heidelberg, Germany. Of these, 250 patients with SR were individually matched to 250 patients with AF with respect to NT-proBNP, New York Heart Association functional class, sex, age, and aetiology of CHF. In the general sample, both AF and NT-proBNP were associated with all-cause mortality [hazard ratio (HR) = 1.96, 95% confidence interval (CI) 1.61-2.39, P < 0.001; and HR = 1.03 per 1000 ng/L increase, 95% CI 1.02 to 1.04, P < 0.001, respectively]. After matching, NT-proBNP retained its prognostic power (HR = 1.13 per 1000 ng/L increase, 95% CI 1.10 to 1.16, P < 0.001), but AF did not (HR = 0.91, 95% CI 0.66 to 1.25, P = 0.56). Despite similar prognosis, matched patients with SR were in more advanced CHF than were AF patients as indicated by a lower left ventricular ejection fraction (30 ± 13% vs. 34 ± 14%, P < 0.001).

CONCLUSIONS

The prognostic value of NT-proBNP in CHF is not influenced by concomitant AF. AF, in return, might be a surrogate of a worse cardiac condition rather than an independent risk factor.

How to Improve Cardiac Resynchronization Therapy Benefit in Atrial Fibrillation Patients: Pulmonary Vein Isolation (and Beyond)

Although cardiac resynchronization therapy (CRT) is an important treatment of symptomatic heart failure patients in sinus rhythm with low left ventricular ejection fraction and ventricular dyssynchrony, its role is not well defined in patients with atrial fibrillation (AF). CRT is not as effective in patients with AF because of inadequate biventricular capture and loss of atrioventricular synchrony. Both can be addressed with catheter ablation of AF. It is still unclear if these therapies offer additive benefits in patients with ventricular dyssynchrony. This article discusses the role and techniques of catheter ablation of AF in patients with heart failure, and its application in CRT recipients.

Relaxin Level in Patients With Atrial Fibrillation and Association with Heart Failure Occurrence: A STROBE Compliant Article

Atrial fibrillation (AF) is the most common arrhythmia requiring medical treatment and has been associated with enhanced atrial fibrosis and heart failure (HF). Relaxin (RLX), an antifibrosis and antiinflammatory peptide hormone, may be used to evaluate atrial fibrosis and is associated with HF occurrence in AF. We aimed to clarify the clinical significance of RLX level in patients with AF.We measured circulating levels of RLX and other fibrosis-related factors in 311 patients with sinus rhythm (SR; n = 116) or AF (n = 195). All discharged AF patients were followed up for the occurrence of HF for a mean of 6 months.Circulating levels of RLX were significantly different in patients with AF as compared with SR (P < 0.001), and in the subgroup analysis of AF. RLX level was correlated with left atrial diameter (LAD; R = 0.358, P < 0.001). Among followed up AF patients, on Kaplan-Meier curve analysis, patients with the third RLX tertile (T3) had a significantly higher HF rate than those with the 1st tertile (T1) (P = 0.002) and the cut-off value was 294.8 ng/L (area under the ROC curve [AUC] = 0.723). On multivariable analysis, HF occurrence with AF was associated with increased tertile of serum RLX level (odds ratio [OR] 2.659; confidence interval [95% CI] 1.434-4.930; P = 0.002).RLX is associated with fibrosis-related biomarkers and significantly elevated in AF. RLX was related to the HF occurrence in patients with AF.

How to Improve Cardiac Resynchronization Therapy Benefit in Atrial Fibrillation Patients: Pulmonary Vein Isolation (and Beyond)

Although cardiac resynchronization therapy (CRT) is an important treatment of symptomatic heart failure patients in sinus rhythm with low left ventricular ejection fraction and ventricular dyssynchrony, its role is not well defined in patients with atrial fibrillation (AF). CRT is not as effective in patients with AF because of inadequate biventricular capture and loss of atrioventricular synchrony. Both can be addressed with catheter ablation of AF. It is still unclear if these therapies offer additive benefits in patients with ventricular dyssynchrony. This article discusses the role and techniques of catheter ablation of AF in patients with heart failure, and its application in CRT recipients.

Digoxin treatment is associated with increased total and cardiovascular mortality in anticoagulated patients with atrial fibrillation

BACKGROUND

Some evidences suggest that the use of digoxin may be harmful inatrial fibrillation (AF) patients. The aim of the study was to investigate in a "real world" of AF patients receiving vitamin K antagonists (VKAs), the relationship between digoxin use and mortality.

METHODS

Prospective single-center observational study including 815 consecutive non-valvular AF patients treated with VKAs. Total mortality was the primary outcome of the study. We also performed a sub-analysis considering only cardiovascular (CV) deaths. Time in therapeutic range (TTR) was used for anticoagulation quality.

RESULTS

Median follow-up was 33.2months (2460 person-years); 171 (21.0%) patients were taking digoxin. Compared to those without, patients on digoxin were older (p=0.007), with a clinical history of HF (p<0.001) and at higher risk of thromboembolic events (p<0.001). No difference in TTR between the two groups was registered (p=0.598). During the follow-up, 85 deaths occurred: 47 CV and 38 non-CV deaths; 35 deaths occurred in digoxin users (20.6%). A significant increased rate of total mortality was observed in digoxin-treated patients (p<0.001). Multivariable analysis showed that digoxin was associated with total mortality (hazard ratio [HR]: 2.224, p<0.001) and CV death (HR: 4.686, p<0.001). A propensity score-matched analysis confirmed that digoxin was associated with total mortality (HR: 2.073, p=0.0263) and CV death (HR: 4.043, p=0.004).

CONCLUSIONS

In AF patients on good anticoagulation control with VKAs, digoxin use was associated with a higher rate of total and CV mortality.

Usefulness of pharmacologic conversion of atrial fibrillation during dofetilide loading without the need for electrical cardioversion to predict durable response to therapy

Conversion of persistent atrial fibrillation (AF) to sinus rhythm is frequently seen during the 3-day in-hospital loading period required during dofetilide initiation, but it is not known whether pharmacologic conversion (PC) without the need for electrical cardioversion (EC) is a predictor of long-term maintenance of sinus rhythm during continued therapy with dofetilide. We sought to test the hypothesis that PC predicts durable maintenance of sinus rhythm and determine additional predictors of long-term maintenance of sinus rhythm on dofetilide. We retrospectively reviewed all elective inpatient admissions for dofetilide loading from 2003 to 2011 at the University of Virginia. A multivariate Cox proportional hazards model was used to assess predictors of maintenance of sinus rhythm after in-hospital dofetilide loading. In all, 101 patients with a current duration of AF lasting for a median of 1.86 months (interquartile range 0.47 to 6.03) were included in the analysis. Forty-seven patients were in the PC group, whereas 54 patients were in the EC group. Patients in the PC group remained longer in sinus rhythm compared with the patients in the EC group (log-rank p = 0.032). The seventy-fifth percentile for the current episode duration in the PC group was 5.77 months, indicating that even long-standing persistent AF frequently converted pharmacologically. Hypertension and a longer duration of the current AF episode were also predictors of recurrence in the multivariate model. In conclusion, PC during in-hospital dofetilide loading is an important predictor of durable response even in long-standing persistent patients, which has important public health implications for choice of therapy.

Management strategies in atrial fibrillation in patients with heart failure

Atrial fibrillation (AF) and heart failure (HF) frequently occur together, and their coexistence is associated with a poor prognosis. AF and HF share risk factors, but their relationship involves complex hemodynamic, neurohormonal, inflammatory, ultrastructural, and electrophysiologic processes that extend beyond epidemiological associations. The shared mechanisms underlying AF and HF have important implications for the treatment of AF in patients with HF. This article focuses on reviewing contemporary data as it pertains to AF management in patients with HF and provides insight into investigational therapies currently under development.

Cyclic adenosine monophosphate phosphodiesterase type 4 protects against atrial arrhythmias

OBJECTIVES

This study was designed to examine whether a cyclic adenosine monophosphate (cAMP) phosphodiesterase (PDE), PDE4, is expressed in human atrium and contributes to the control of electrical stability.

BACKGROUND

Atrial fibrillation is accompanied by a profound remodeling of membrane receptors and alterations in cAMP-dependent regulation of Ca(2+) handling. Being responsible for cAMP hydrolysis, PDEs are likely to play a role in this setting. In the rodent heart, PDE4 contributes up to 60% of total cAMP-hydrolytic activity. However, its role in the human heart remains controversial.

METHODS

L-type Ca(2+) current and spontaneous Ca(2+) release were recorded in isolated human atrial myocytes. Intracellular cAMP was measured by live cell imaging using a fluorescence resonance energy transfer-based sensor. Contractile force and arrhythmias were recorded in human atrial trabeculae. PDE activity was measured in human atrial tissue from patients in sinus rhythm and permanent atrial fibrillation.

RESULTS

PDE4 is expressed in human atrial myocytes and accounts for approximately 15% of total PDE activity. PDE4D represents the major PDE4 subtype. PDE4 inhibition increased intracellular cAMP and L-type Ca(2+) current and dramatically delayed their decay after a brief β-adrenergic stimulation. PDE4 inhibition also increased the frequency of spontaneous Ca(2+) release at baseline, as well as the contractile response and the incidence of arrhythmias in human atrial strips during β-adrenergic stimulation. Total PDE activity decreased with age, and the relative PDE4 activity was lower in patients with permanent atrial fibrillation than in age-matched sinus rhythm controls.

CONCLUSIONS

PDE4 is critical in controlling cAMP levels and thereby Ca(2+) influx and release in human atrial muscle, hence limiting the susceptibility to arrhythmias.

Prevalence of isolated atrial amyloidosis in young patients affected by congestive heart failure

Atrial natriuretic peptide (ANP), whose amyloid is responsible of isolated atrial amyloidosis (IAA), is known to play an important role in the pathophysiology of congestive heart failure (CHF). We provide here the microscopic examination of atrial biopsies from 36 young (mean 40 years) CHF patients distinguished in idiopathic dilated cardiomyopathy (DC) affected and hypertrophic Cardiomyopathy (HC) affected, endorsing the presumptive association of early CHF with IAA. We utilized a multiple method, using Congo red (CR) staining, CR fluorescence (CRF), and immunohistochemistry to assess the presence of IAA in CHF. Immunostaining showed a moderate deposition of IAA in the atrium surrounding working myocardium with small intracellular deposits. Our findings suggest a monitoring of young CHF cases for the development of IAA. Our study also demonstrated how the concurrent use of immunohistochemistry, CR, and CRF may greatly enhance the detection of low-grade amyloid deposits.

Atrial fibrillation and mortality in heart failure: a community study

BACKGROUND

Heart failure (HF) and atrial fibrillation (AF) share common risk factors and often coexist. The combination of HF and AF may carry a worse prognosis than either condition alone; however, the magnitude of this risk remains controversial and it is not known whether the timing of AF influences the risk of death.

METHODS AND RESULTS

We determined the risk of all-cause mortality in relation to the presence of AF prior to or after HF diagnosis in a community-based cohort of persons diagnosed as having HF between 1983 and 2006. Of 1664 individuals with HF, 553 had a history of AF and 384 developed AF after HF. During a median follow-up of 4.0 years, 450 deaths occurred among persons with prior AF, 314 among those with AF after HF, and 572 among patients without AF. In fully adjusted models, compared with patients without AF, those with AF prior to HF had a 29% increased risk of death, whereas those who developed AF after HF exhibited >2-fold increased risk of death.

CONCLUSIONS

In the community, AF is frequent in the setting of HF and is associated with a large excess risk of death. The magnitude of this excess risk differs markedly according to the timing of AF, with AF developing after HF conferring the largest increased risk of death compared with HF patients without AF.

Autonomic dysfunction and new-onset atrial fibrillation in patients with left ventricular systolic dysfunction after acute myocardial infarction: a CARISMA substudy

BACKGROUND

Atrial fibrillation (AF) increases morbidity and mortality in patients with previous myocardial infarction and left ventricular systolic dysfunction. The purpose of this study was to identify patients with a high risk for new-onset AF in this population using invasive and noninvasive electrophysiological tests.

METHODS

The study included 271 patients from the Cardiac Arrhythmias and RIsk Stratification after Myocardial InfArction (CARISMA) study with an acute myocardial infarction (AMI) and left ventricular ejection fraction ≤40% without previous AF at enrollment. Within 21 days after the AMI, an implantable loop recorder was inserted and used to diagnose AF over the 2-year study duration. The following tests were performed: heart rate variability (HRV) and turbulence (HRT) analyses from repeated 24-hour Holter recordings, 2-dimensional (2D)-echocardiograms, exercise test, and programmed electrophysiologic stimulation.

RESULTS

A total of 101 patients (37%) developed AF during the study. Predictive measures included several indexes of HRV including reduced low-frequency (LF) power from spectral HRV analysis (adjusted HR = 1.6, P = 0.034), HRT slope ≤2.5 (HR = 1.6, P = 0.032) and Detrended Fluctuation Analysis (DFA1) from HRV analysis (HR = 1.8, P = 0.011); all are measures of cardiac autonomic nervous system dysfunction. Combined with age >60 years, low values for LF, HRT slope, and DFA1 provided a powerful risk score for prediction of new-onset AF (1-2 points: HR = 4.3, P = 0.001, 3-4 points: HR = 7.0, P < 0.001).

CONCLUSION

Abnormal HRV and HRT parameters, which are associated with disturbances in the cardiac autonomic regulation, are associated with increased risk of new-onset AF independently of conventional clinical risk variables.

MicroRNA-328 contributes to adverse electrical remodeling in atrial fibrillation

BACKGROUND

A characteristic of both clinical and experimental atrial fibrillation (AF) is atrial electric remodeling associated with profound reduction of L-type Ca(2+) current and shortening of the action potential duration. The possibility that microRNAs (miRNAs) may be involved in this process has not been tested. Accordingly, we assessed the potential role of miRNAs in regulating experimental AF.

METHODS AND RESULTS

The miRNA transcriptome was analyzed by microarray and verified by real-time reverse-transcription polymerase chain reaction with left atrial samples from dogs with AF established by right atrial tachypacing for 8 weeks and from human atrial samples from AF patients with rheumatic heart disease. miR-223, miR-328, and miR-664 were found to be upregulated by >2 fold, whereas miR-101, miR-320, and miR-499 were downregulated by at least 50%. In particular, miR-328 level was elevated by 3.9-fold in AF dogs and 3.5-fold in AF patients relative to non-AF subjects. Computational prediction identified CACNA1C and CACNB1, which encode cardiac L-type Ca(2+) channel α1c- and β1 subunits, respectively, as potential targets for miR-328. Forced expression of miR-328 through adenovirus infection in canine atrium and transgenic approach in mice recapitulated the phenotypes of AF, exemplified by enhanced AF vulnerability, diminished L-type Ca(2+) current, and shortened atrial action potential duration. Normalization of miR-328 level with antagomiR reversed the conditions, and genetic knockdown of endogenous miR-328 dampened AF vulnerability. CACNA1C and CACNB1 as the cognate target genes for miR-328 were confirmed by Western blot and luciferase activity assay showing the reciprocal relationship between the levels of miR-328 and L-type Ca(2+) channel protein subunits.

CONCLUSIONS

miR-328 contributes to the adverse atrial electric remodeling in AF through targeting L-type Ca(2+) channel genes. The study therefore uncovered a novel molecular mechanism for AF and indicated miR-328 as a potential therapeutic target for AF.

Levosimendan - a calcium sensitising agent with potential anti-arrhythmic properties

Levosimendan is a 'Ca(2+)sensitiser', which exerts its inotropic effect by increasing the affinity of troponin C for Ca(2+), directly stabilising the Ca(2+)-induced conformation of troponin C. It leads to a positive inotropic effect without impairing diastolic relaxation and causing cytosolic Ca(2+) ion overload, which might result in cardiac myocyte dysfunction, arrhythmias and cell death. Levosimendan may also have significant anti-inflammatory properties. Data from various studies suggest that levosimendan might have anti-arrhythmic effects, although the outcome of clinical trials on the effect of this agent in (for example) atrial fibrillation (AF) remains controversial. Currently, on the basis of available data, it is especially worth emphasising the potential role of this drug in the termination of AF after cardiac surgery, which significantly influences early- and long-term morbidity and mortality. This review considers the putative anti-arrhythmic properties of levosimendan and discusses the potential clinical application of such a drug.

Dronedarone Therapy in Atrial Fibrillation: A Summary of Recent Controlled Trials

Dronedarone is a new multichannel blocker, structurally related to amiodarone but free of iodine and less lipophilic and so expected to be free of iodine-related organ toxicity and tissue accumulation. The drug was developed for the treatment of atrial fibrillation (AF). The phase II Dronedarone Atrial FibrillatioN study after Electrical cardioversion (DAFNE) study established 400 mg twice-daily dosing (bid) as the standard dose for dronedarone in the maintenance of sinus rhythm. In the pivotal phase III European Trial In Atrial Fibrillation Or Flutter Patients Receiving Dronedarone For The Maintenance of Sinus Rhythm/ American-Australian-African Trial With Dronedarone In Atrial Fibrillation/flutter Patients For The Maintenance of Sinus Rhythm (EURIDIS/ADONIS) studies in patients with paroxysmal/persistent AF and atrial flutter, dronedarone significantly prolonged the mean time to first AF/flutter recurrence. Although dronedarone proved to be safe in these AF studies, a trial in patients with severe congestive heart failure was prematurely stopped because of excess mortality in the dronedarone relative to the control group. This finding prompted the conduct of a large randomized study in more than 4600 patients with nonpermanent AF, which used the primary end point of time to first cardiovascular (CV) hospitalization or death. Dronedarone significantly reduced the incidence of the primary as well as several secondary end points among which CV mortality was the most significant one. The results of this development program led to the approval of dronedarone for use in patients with AF in several jurisdictions. This article provides a short summary of the most important findings during the clinical development of dronedarone.

Blood pressure and cognitive function in older adults with cardiovascular disease

BACKGROUND

Past studies link elevated blood pressure (BP) and BP variability to adverse neurocognitive changes in community samples. However, little is known about the relationship between BP indices and cognitive function in older CVD patients.

METHODS

A total of 99 older adults with CVD completed a comprehensive neuropsychological test battery. Resting BP measurements were collected every 10 min for 2 hr during a separate cardiac assessment. Five BP indices were generated: average and standard deviation of systolic blood pressure (SBP), average and standard deviation of diastolic blood pressure (DBP), and a function of systolic variability and average diastolic pressure. We examined the relationship between these BP indices and cognitive function.

RESULTS

Partial correlation adjusting for age and education revealed that the function of systolic variability and average diastolic pressure (SBP standard deviation divided by the average DBP) was most closely related to test performance, showing significant associations to both Learning/Memory (r = 0.25) and Language functioning (r = 0.22). SBP indices were also related to Language functioning (SBP avg., r = 0.22; SBP SD, r = 0.25), though DBP indices were unrelated to performance in any cognitive domain.

CONCLUSIONS

The current findings indicate that BP is modestly related to cognitive function in older CVD patients. Contrary to expectations, greater BP variability was associated with better, not poorer, cognitive test performance. Such findings suggest that the relationship between BP and cognitive function is more complicated than typically believed and requires further examination.

Association of the parameters derived from the relation between RR intervals and left ventricle performance with a history of heart failure in patients with atrial fibrillation

Parameters derived from the relation between RR intervals and left ventricular (LV) performance in atrial fibrillation (AF) have been useful to evaluate systolic LV function. This study investigated the association of these parameters with a history of heart failure. Echocardiography was performed in 107 patients with AF. LV outflow peak ejection velocity (Vpe) was adjusted for the effect of pre-preceding RR interval (RR-2) using the logarithmic equation between RR-2 and Vpe. The logarithmic equation between adjusted Vpe and preceding RR interval (RR-1) was calculated in the co-ordinates with RR-1 from 0.6 to 1 second. From this equation, the ratio of slope to Vpe at RR-1 = 1 second (slope/Vpe-1) was obtained. When patients were divided into 2 groups according to a history of heart failure, old age, high slope/Vpe-1, mitral regurgitation, and left atrial enlargement independently predicted the occurrence of heart failure. Fractional shortening was not different between the 2 groups. In patients with normal LV size and without significant regurgitation (n = 69), old age and high slope/Vpe-1 independently predicted the occurrence of heart failure. Areas under the receiver operating characteristics curve of slope/Vpe-1 for identifying heart failure were 0.72 (p <0.000) and 0.74 (p <0.001) in all patients and in patients with normal LV size, respectively. In conclusion, the new parameter, slope/Vpe-1, was one of the most useful predictors for the occurrence of heart failure in AF and was superior to the classic hemodynamic parameters. This parameter might be determined not only by systolic function but also by diastolic function of the left ventricle.

Reduced phosphoinositide 3-kinase (p110alpha) activation increases the susceptibility to atrial fibrillation

Atrial fibrillation (AF) is the most common sustained arrhythmia presenting at cardiology departments. A limited understanding of the molecular mechanisms responsible for the development of AF has hindered treatment strategies. The purpose of this study was to assess whether reduced activation of phosphoinositide 3-kinase (PI3K, p110alpha) makes the compromised heart susceptible to AF. Risk factors for AF, including aging, obesity, and diabetes, have been associated with insulin resistance that leads to depressed/defective PI3K signaling. However, to date, there has been no link between PI3K(p110alpha) and AF. To address this question, we crossed a cardiac-specific transgenic mouse model of dilated cardiomyopathy (DCM) with a cardiac-specific transgenic mouse expressing a dominant negative mutant of PI3K (dnPI3K; reduces PI3K activity). Adult ( approximately 4.5 months) double-transgenic (dnPI3K-DCM), single-transgenic (DCM-Tg, dnPI3K-Tg), and nontransgenic mice were subjected to morphological, functional/ECG, microarray, and biochemical analyses. dnPI3K-DCM mice developed AF and had depressed cardiac function as well as greater atrial enlargement and fibrosis than DCM-Tg mice. AF was not detected in other groups. Aged DCM-Tg mice ( approximately 15 months) with a similar phenotype to dnPI3K-DCM mice (4.5 months) did not develop AF, suggesting loss of PI3K activity directly contributed to the AF phenotype. Furthermore, increasing PI3K activity reduced atrial fibrosis and improved cardiac conduction in DCM-Tg mice. Finally, in atrial appendages from patients with AF, PI3K activation was lower compared with tissue from patients in sinus rhythm. These results suggest a link between PI3K(p110alpha) and AF.

Special cases in acute heart failure syndromes: atrial fibrillation and wide complex tachycardia

Hospitalization for acute heart failure syndromes (AHFS) results in substantial in-hospital and postdischarge morbidity and mortality. Management of AHFS presents significant challenges, given the heterogeneity of the patient population and the differing etiologies underlying why patients present with acute decompensation. Arrhythmias in the setting of AHFS, such as atrial fibrillation and wide complex tachycardia, present additional challenges. Compounding this challenge is the paucity of evidence on which to base early management. General principles for the management of atrial fibrillation and wide complex tachycardia in the setting of emergency department AHFS are discussed.

Implantable CRT device diagnostics identify patients with increased risk for heart failure hospitalization

PURPOSE

To determine the association between device-determined diagnostic indices, including intrathoracic impedance, and heart failure (HF) hospitalization.

METHODS

Clinical and device diagnostic data of 558 HF patients indicated for CRT-D therapy (In Sync Sentry, Medtronic Inc.) were prospectively collected from 34 centers. Device-recorded intrathoracic impedance fluid index threshold crossing event (TCE), mean activity counts, tachyarrhythmia events, night heart rate (NHR) and heart rate variability (HRV) were compared within patients with vs. without documented HF hospitalization.

RESULTS

Mean follow-up was 326 +/- 216 days. Patients hospitalized for HF had significantly higher rates of TCE, a higher percentage of days with the thoracic impedance fluid index above the programmed threshold, a higher percentage of days with low activity, with low HRV or with high NHR. Multivariate analysis showed that TCE resulted in a 36% increased probability of HF hospitalization. Both TCE duration and patient activity were also significantly associated with hospitalization. Kaplan Meier analysis indicated that patients with more TCE events were significantly more likely to be hospitalized (log rank test, p = 0.005).

CONCLUSIONS

Decreased intrathoracic impedance, low patient activity and low HRV were all independently associated with increased risk for HF hospitalization in HF patients treated with resynchronization therapy. Device-derived diagnostic data may provide valuable and reliable indices for the prognostic stratification of HF patients.

Risk of cardiovascular and cerebrovascular events after atrial fibrillation diagnosis

BACKGROUND

Atrial fibrillation (AF) is associated with subsequent cardiovascular events including ischemic stroke, transient ischemic events, and coronary events. This study aimed to evaluate the risk of ischemic cerebrovascular events (ICVE), coronary events (CE) or heart failure (HF) following a diagnosis of AF.

METHODS

Patients were selected from the UK General Practice Research Database. The incidence of ICVE, CE and HF was determined during a 6-year follow-up period for patients with a first diagnosis of AF (n=831) and a control group without AF (n=8226). Relative risk of developing a cardiovascular event associated with prior AF and other potential risk factors was estimated using Cox regression analysis.

RESULTS

A first diagnosis of ICVE, CE or HF was made in 261 patients in the AF group and 622 in the control group. The relative risks associated with AF were 2.1 for CE (95% CI: 1.6-2.9), 3.0 for ICVE (95% CI: 2.3-4.0) and 6.4 for HF (95% CI: 5.0-8.3). The risks of CE, HF and ICVE were higher in patients with chronic AF than paroxysmal AF (odds ratio: 1.5, 95% CI: 1.0-2.2) and in patients aged at least 60 years or with diabetes. Lifestyle factors did not significantly affect the risk of cardiovascular events in patients with AF.

CONCLUSIONS

After a first episode of AF there is an increased risk of ICVE, CE and HF. Patients initially diagnosed with chronic AF have a higher risk than those with paroxysmal AF.

P-wave duration and dispersion in obese subjects

BACKGROUND

Although previous studies have documented a variety of electrocardiogram (ECG) abnormalities in obesity, P-wave alterations, which represent an increased risk for atrial arrhythmia, have not been studied very well in these patients. The aim of the present study was to evaluate P-wave duration and P dispersion (Pd) in obese subjects, and to investigate the relationship between P-wave measurements, and the clinical and echocardiographic variables.

METHODS

The study population consisted of 52 obese and 30 normal weight control subjects. P-wave duration and P-wave dispersion were calculated on the 12-lead ECG. As echocardiographic variables, left atrial diameter (LAD), left ventricular end-diastolic, and end-systolic diameters (LVDD and LVSD), left ventricular ejection fraction (LVEF), interventricular septum thickness (IVST), left ventricular posterior wall thickness (LVPWT), and left ventricular mass (LVM) of the obese and the control subjects were measured by means of transthoracic echocardiography.

RESULTS

There were statistically significant differences between obese and controls as regards to Pmax (maximum P-wave duration) and Pd (P dispersion) (P < 0.001 and P < 0.001, respectively). Pmin (minimum P wave duration) was similar in both groups. Correlation analysis showed that Pd in the obese patients was related to any the clinical and echocardiographic parameters including BMI, LAD, LVDD, IVST, LVPWT, and LVM.

CONCLUSION

Our data suggest that obesity affects P-wave dispersion and duration, and changes in P dispersion may be closely related to the clinical and the echocardiographic parameters such as BMI, LAD, IVST, LVPWT, and LVM.

Adrenergic regulation of a key cardiac potassium channel can contribute to atrial fibrillation: evidence from an I Ks transgenic mouse

Inherited gain-of-function mutations of genes coding for subunits of the heart slow potassium (I Ks) channel can cause familial atrial fibrillation (AF). Here we consider a potentially more prevalent mechanism and hypothesize that beta-adrenergic receptor (beta-AR)-mediated regulation of the I Ks channel, a natural gain-of-function pathway, can also lead to AF. Using a transgenic I Ks channel mouse model, we studied the role of the channel and its regulation by beta-AR stimulation on atrial arrhythmias. In vivo administration of isoprenaline (isoproterenol) predisposes I Ks channel transgenic mice but not wild-type (WT) littermates that lack I Ks to prolonged atrial arrhythmias. Patch-clamp analysis demonstrated expression and isoprenaline-mediated regulation of I Ks in atrial myocytes from transgenic but not WT littermates. Furthermore, computational modelling revealed that beta-AR stimulation-dependent accumulation of open I Ks channels accounts for the pro-arrhythmic substrate. Our results provide evidence that beta-AR-regulated I Ks channels can play a role in AF and imply that specific I Ks deregulation, perhaps through disruption of the I Ks macromolecular complex necessary for beta-AR-mediated I Ks channel regulation, may be a novel therapeutic strategy for treating this most common arrhythmia.

Valoración clínica, ecocardiográfica y pronóstica de la fibrilación auricular en pacientes con insuficiencia cardíaca

BACKGROUND AND OBJECTIVE

We aimed to assess the prevalence of atrial fibrillation (AF) in a general heart failure (HF) population admitted to a HF unit, analyze the parameters associated with AF, and evaluate its prognostic significance.

PATIENTS AND METHOD

389 patients, 64 with AF at the first visit. Mean (SD) age was 65.38 (10.77) years and 72.5% were men. The main etiology was ischemic heart disease (59.9%). Mean ejection fraction (EF) was 32.25% (13%). Vital status at 2 years was available in 377 patients (97%), 314 in sinus rhythm (SR) and 63 in AF.

RESULTS

The prevalence of AF was 15.8%. AF was associated with: older age, female gender, valvular and hypertensive etiology, longer time since the onset of HF symptoms, higher EF, higher left atrium diameter, degree of mitral regurgitation, and lower quality of life, but not with the NYHA functional class. The 2-years mortality (16.7%) was significantly higher in patients with AF (33.3% vs 18.4%; OR = 2.20; 95% confidence interval, 1.21-4). However, when adjusted for other relevant variables such as age, NYHA functional class, ejection fraction, sex and etiology, AF did not remain as an independent prognostic factor. The strongest mortality differences between patients with AF and those with SR where observed in ischemic heart disease and dilated cardiomyopathy.

CONCLUSIONS

AF was associated mainly with age, valvular and hypertensive etiology, higher left atrium diameter and lower end-systolic left ventricular diameter. Two years mortality was significantly higher in patients with AF, although other parameters such as age and NYHA functional class had a higher prognostic value.