Atrial fibrillation in heart failure is associated with an increased risk of death only in patients with ischaemic heart disease

One-year outcomes in cardiogenic shock triggered by supraventricular tachycardia: an analysis of the FRENSHOCK multicenter prospective registry

Background

Cardiogenic shock (CS) is the most severe form of heart failure (HF), resulting in high early and long-term mortality. Characteristics of CS secondary to supraventricular tachycardia (SVT) are poorly reported. Based on a large registry of unselected CS, we aimed to compare 1-year outcomes between SVT-triggered and non-SVT-triggered CS.

Methods

FRENSHOCK is a French prospective registry including 772 CS patients from 49 centers. For each patient, the investigator could report 1-3 CS triggers from a pre-established list (ischemic, mechanical complications, ventricular/supraventricular arrhythmia, bradycardia, iatrogenesis, infection, non-compliance, and others). In this study, 1-year outcomes [rehospitalizations, mortality, heart transplantation (HTx), ventricular assist devices (VAD)] were analyzed and adjusted for independent predictive factors.

Results

Among 769 CS patients included, 100 were SVT-triggered (13%), of which 65 had SVT as an exclusive trigger (8.5%). SVT-triggered CS patients exhibited a higher proportion of male individuals with a more frequent history of cardiomyopathy or chronic kidney disease and more profound CS (biventricular failure and multiorgan failure). At 1 year, there was no difference in all-cause mortality (43% vs. 45.3%, adjusted HR 0.9 (95% CI 0.59-1.39), p = 0.64), need for HTx or VAD [10% vs. 10%, aOR 0.88 (0.41-1.88), p = 0.74], or rehospitalizations [49.4% vs. 44.4%, aOR 1.24 (0.78-1.98), p = 0.36]. Patients with SVT as an exclusive trigger presented more 1-year rehospitalizations [52.8% vs. 43.3%, aOR 3.74 (1.05-10.5), p = 0.01].

Conclusion

SVT is a frequent trigger of CS alone or in association in more than 10% of miscellaneous CS cases. Although SVT-triggered CS patients were more comorbid with more pre-existing cardiomyopathies and HF incidences, they presented similar rates of mortality, HTx, and VAD at 1 year, arguing for a better overall prognosis.

Clinical Trial Registration

https://clinicaltrials.gov, identifier: NCT02703038.

Differences in the Clinical Outcome of Ischemic and Nonischemic Cardiomyopathy in Heart Failure With Concomitant Opioid Use Disorder

Heart Failure (HF) and Opioid Use Disorder (OUD) independently have significant impact on patients and the United States (US) health system. In the setting of the opioid epidemic, research on the effects of OUD on cardiovascular diseases is rapidly evolving. However, no study exists on differential outcomes of ischemic cardiomyopathy (ICM) and nonischemic cardiomyopathy (NICM) in patients with HF with OUD. We performed a retrospective, observational cohort study using National Inpatient Sample (NIS) 2018-2020 databases. Patients aged 18 years and above with diagnoses of HF with concomitant OUD were included. Patients were further classified into ICM and NICM. Primary outcome of interest was differences in all- cause in-hospital mortality. Secondary outcome was incidence of cardiogenic shock. We identified 99,810 hospitalizations that met inclusion criteria, ICM accounted for 27%. Mean age for ICM was higher compared to NICM (63 years vs 56 years, P < 0.01). Compared to NICM, patients with ICM had higher cardiovascular disease risk factors and comorbidities; type 2 diabetes mellitus (46.3 % vs 30.1%, P < 0.01), atrial fibrillation/flutter (33.5% vs 29.9%, P < 0.01), hyperlipidemia (52.5% vs 28.9%, P < 0.01), and Charlson comorbidity index ≥5 was 46.7% versus 29.7%, P < 0.01. After controlling for covariates and potential confounders, we observed higher odds of all-cause in-hospital mortality in patients with NICM (aOR = 1.36; 95% CI:1.03-1.78, P = 0.02). There was no statistical significant difference in incidence of cardiogenic shock between ICM and NICM (aOR = 0.86;95% CI 0.70-1.07, P = 0.18). In patients with HF with concomitant OUD, we found a 36% increase in odds of all-cause in-hospital mortality in patients with NICM compared to ICM despite being younger in age with less comorbidities. There was no difference in odds of in-hospital cardiogenic shock in this study population. This study contributes to the discussion of OUD and cardiovascular diseases which is rapidly developing and requires further prospective studies.

Atrial fibrillation onset before heart failure or vice versa: what is worst? A nationwide register study

AIMS

Atrial fibrillation (AF) and heart failure (HF) often coexist. However, whether AF onset before HF or vice versa is associated with the worst outcome remains unclear. A consensus of large studies can guide future research and preventive strategies to better target high-risk patients.

METHODS AND RESULTS

We included all Danish cases with the coexistence of AF and HF (2005-17) using nationwide registries. Patients were divided into three separate groups (i) AF before HF, (ii) HF before AF, or (iii) AF and HF diagnosed concurrently (±30 days). Adjusting landmark Cox analyses (index date was the time of the latter diagnosis of AF or HF) were used for evaluating the association of the three groups with a composite outcome of ischaemic stroke or death. Among a total of 49 042 patients included, 40% had AF before HF, 27% had HF before AF, and 33% had AF and HF diagnosed concurrently. The composite endpoint accrued more often in patients with HF before AF compared to the two other groups (<0.001), and this remained significant in the adjusted analyses with hazard ratios (95% confidence intervals) of 1.26 (1.22-1.30) compared to AF before HF. Finally, antihypertensive treatment, oral anticoagulants, amiodarone, statins, and AF ablation were associated with a lower hazard ratio of the composite endpoint (all < 0.001).

CONCLUSIONS

In this large Danish national cohort, diagnosis of HF before AF was associated with an increased absolute risk of death compared to AF before HF and AF and HF diagnosed concurrently. Antihypertensive treatment, oral anticoagulants, amiodarone, statins, and AF ablation may improve prognosis.

Atrial fibrillation is a marker of increased mortality risk in nonischemic heart failure-Results from the DANISH trial

BACKGROUND

Atrial fibrillation (AF) in heart failure (HF) patients has been associated with a worse outcome. Similarly, excessive supraventricular ectopic activity (ESVEA) has been linked to development of AF, stroke, and death. This study aimed to investigate AF and ESVEA's association with outcomes and effect of prophylactic implantable cardioverter defibrillator (ICD) implantation in nonischemic HF patients.

METHODS

A total of 850 patients with nonischemic HF, left ventricle ejection fraction ≤35%, and elevated N-terminal pro-brain natriuretic peptides underwent 24 hours Holter recording. The presence of AF (≥30 seconds) and ESVEA (≥30 supraventricular ectopic complexes (SVEC) per hour or run of SVEC ≥20 beats) were registered. Outcomes were all-cause mortality, cardiovascular death (CVD), and sudden cardiac death (SCD).

RESULTS

AF was identified in 188 patients (22%) and ESVEA in 84 patients (10%). After 4 years and 11 months of follow-up, a total of 193 patients (23%) had died. AF was associated with all-cause mortality (hazard ratio [HR] 1.44; confidence interval [CI] 1.04-1.99; P = .03) and CVD (HR 1.59; CI 1.07-2.36; P = .02). ESVEA was associated with all-cause mortality (HR 1.73; CI 1.16-2.57; P = .0073) and CVD (HR 1.76; CI 1.06-2.92; P = .03). Neither AF nor ESVEA was associated with SCD. ICD implantation was not associated with an improved prognosis for neither AF (P value for interaction = .17), nor ESVEA (P value for interaction = .68).

CONCLUSIONS

Both AF and ESVEA were associated with worsened prognosis in nonischemic HF. However, ICD implantation was not associated with an improved prognosis for either group.

Tobacco smoking in patients with heart failure and coronary artery disease: A 20-year experience at Duke University Medical Center

Smoking is associated with incident heart failure (HF), yet limited data are available exploring the association between smoking status and long-term outcomes in HF with reduced vs. preserved ejection fraction (i.e., HFrEF vs. HFpEF).

METHODS

We performed a retrospective analysis of HF patients undergoing coronary angiography from 1990-2010. Patients with coronary artery disease (CAD) and HF were stratified by EF (< 50% vs. ≥50%), smoking status (prior/current vs. never smoker), and level of smoking (light/moderate vs. heavy). Time-from-catheterization-to-event was examined using Cox proportional hazard modeling for all-cause mortality (ACM), ACM/myocardial infarction/stroke (MACE), and ACM/HF hospitalization with testing for interaction by HF-type (HFrEF vs. HFpEF).

RESULTS

Of 14,406 patients with CAD and HF, 85% (n = 12,326) had HFrEF and 15% (n = 2080) had HFpEF. At catheterization, 61% of HFrEF and 57% of HFpEF patients had a smoking history. After adjustment, there was a significant interaction between HF-type and the association between smoking status and MACE (interaction P = .009). Smoking history was associated with increased risk for MACE in patients with HFrEF (adjusted hazard ratio [HR] 1.18 [1.12-1.24]), but not HFpEF (HR 1.01 [0.90-1.12]). Active smokers had increased mortality following adjustment compared to former smokers regardless of HF-type (HFrEF HR 1.19 [1.06-1.32], HFpEF HR 1.30 [1.02-1.64], interaction P = .50). Heavy smokers trended towards increased risk of adverse outcomes versus light/moderate smokers; these findings were consistent across HF-type (interaction P > .12).

CONCLUSION

Smoking history was independently associated with worse outcomes in HFrEF but not HFpEF. Regardless of HF-type, current smokers had higher risk than former smokers.

Meta-Analysis of Atrial Fibrillation and Outcomes in Patients With Heart Failure and Preserved Ejection Fraction

BACKGROUND

Atrial fibrillation (AF) is common in heart failure with preserved ejection fraction (HFpEF); However, the prognostic impact of AF on HFpEF patients has not been fully elucidated.

METHODS

A literature search of the PubMed and EMBASE databases on literature published through April 2019 was undertaken. Combined hazard ratio (HR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects or random-effects models, depending on the heterogeneity. Subgroup analyses, sensitivity analysis and meta-regression analyses were also performed.

RESULTS

Fourteen (14) eligible studies with 1,948,923 patients with HFpEF were included in the analysis. Atrial fibrillation was associated with an 11% increased risk of all-cause mortality in patients with HFpEF (HR 1.11, 95% CI 1.09-1.12). Sensitivity analysis confirmed the stability of the results. The stratification of studies by controlled or uncontrolled confounding factors affected the final estimate (confounder-controlled HR 1.21, 95% CI 1.12-1.30; confounder-uncontrolled HR 1.13, 95% CI 0.96-1.31). In addition, AF was an independent predictor of hospitalisation for heart failure (HR 1.32, 95% CI 1.15-1.52), cardiovascular death (HR 1.38, 95% CI 1.01-1.89) and stroke (HR 1.87, 95% CI 1.54-2.27).

CONCLUSIONS

Atrial fibrillation was associated with worse clinical outcomes in patients with HFpEF. Further investigation is required to see whether AF is the primary offender in these patients or merely a bystander to worse diastolic function.

Ambulatory electrocardiographic monitoring as a diagnostic tool for ischemic heart disease in women

Introduction. Ischemic heart disease(IHD) is currently the leading cause of mortality in women. In this study we aimed to evaluate ambulatory electrocardiographic monitoring(AECGm) as a diagnostic test for IHD in women. Material and method. The study included 225 female who underwent AECGm divided into 2 groups: 136 previously diagnosed with IHD(IHD+) and 89 controls(IHD-). The IHD+ group was subdivided into AECGm ischemia subgroup(I+) and AECGm non-ischemia subgroup(I-). AECGm was assessed for presence of myocardial ischemia (ST segment depression >5mm), duration and ischemic load (the percentage that episodes of myocardial ischemia accounted throughout the recording). Results and discussions. Patients mean age was 62.31±12.51years. The IHD+ and IHD- groups were similar regarding associated risk factors (hypertension, obesity, dyslipidemia, diabetes mellitus), echocardiographic parameters (left ventricular size, ejection fraction, kinetic disorders), minimum and maximum heart rates(MaxHR) on AECGm. Statistically significant differences were identified regarding presence of atrial fibrillation episodes(AFibE) (IHD+:21.3% vs IHD-:8.9%), myocardial ischemia (IHD+:55.14% vs IHD-:42.69%), ischemic load (IHD+:15.23±30.54% vs IHD-:4.7±15.65%), duration of ischemia (IHD+:174.16±380.75 minutes vs IHD-:59.44 ± 209.02 minutes). In multivariate analysis, ischemia episodes, ischemic load and duration of ischemia were predicted by obesity, MaxHR and AFibE. Statistically significant differences were also identified regarding presence of AFibE (I+:30% vs I-:8.9%), MaxHR (I+:120 vs I-:111beats/minute), obesity (I+:20% vs I-:41%), diabetes mellitus (I+:16% vs I-:69%), hypertension (I+:76% vs I-:90%). Conclusions. Although myocardial ischemia was also present in IHD- group, our study demonstrated that the diagnosis of IHD can be established by AECGm using the threshold values of ischemic load (> 27%) and ischemic duration (> 315minutes).

Analysis of Outcomes in Ischemic vs Nonischemic Cardiomyopathy in Patients With Atrial Fibrillation: A Report From the GARFIELD-AF Registry

Importance

Congestive heart failure (CHF) is commonly associated with nonvalvular atrial fibrillation (AF), and their combination may affect treatment strategies and outcomes.

Objective

To assess the treatment strategies and 1-year clinical outcomes of antithrombotic and CHF therapies for patients with newly diagnosed AF with concomitant CHF stratified by etiology (ischemic cardiomyopathy [ICM] vs nonischemic cardiomyopathy [NICM]).

Design, Setting, and Participants

The GARFIELD-AF registry is a prospective, noninterventional registry. A total of 52 014 patients with AF were enrolled between March 2010 and August 2016. A total of 11 738 patients 18 years and older with newly diagnosed AF (≤6 weeks' duration) and at least 1 investigator-determined stroke risk factor were included. Data were analyzed from December 2017 to September 2018.

Exposures

One-year follow-up rates of death, stroke/systemic embolism, and major bleeding were assessed.

Main Outcomes and Measures

Event rates per 100 person-years were estimated from the Poisson model and Cox hazard ratios (HRs) and 95% confidence intervals.

Results

The median age of the population was 71.0 years, 22 987 of 52 013 were women (44.2%) and 31 958 of 52 014 were white (61.4%). Of 11 738 patients with CHF, 4717 (40.2%) had ICM and 7021 (59.8%) had NICM. Prescription of oral anticoagulant and antiplatelet drugs was not balanced between groups. Oral anticoagulants with or without antiplatelet drugs were used in 2753 patients with ICM (60.1%) and 5082 patients with NICM (73.7%). Antiplatelets were prescribed alone in 1576 patients with ICM (34.4%) and 1071 patients with NICM (15.5%). Compared with patients with NICM, use of angiotensin-converting enzyme inhibitors/angiotensin receptor blockers (72.6% [3439] vs 60.3% [4236]) and of β blockers (63.3% [2988] vs 53.2% [3737]) was higher in patients with ICM. Rates of all-cause and cardiovascular death per 100 patient-years were significantly higher in the ICM group (all-cause death: ICM, 10.2; 95% CI, 9.2-11.1; NICM, 7.0; 95% CI, 6.4-7.6; cardiovascular death: ICM, 5.1; 95% CI, 4.5-5.9; NICM, 2.9; 95% CI, 2.5-3.4). Stroke/systemic embolism rates tended to be higher in ICM groups compared with NICM groups (ICM, 2.0; 95% CI, 1.6-2.5; NICM, 1.5; 95% CI, 1.3-1.9). Major bleeding rates were significantly higher in the ICM group (1.1; 95% CI, 0.8-1.4) compared with the NICM group (0.7; 95% CI, 0.5-0.9).

Conclusions and Relevance

Patients with ICM received oral anticoagulants with or without antiplatelet drugs less frequently and antiplatelets alone more frequently than patients with NICM, but they received angiotensin-converting enzyme inhibitors/angiotensin receptor blockers more often than patients with NICM. All-cause and cardiovascular death rates were higher in patients with ICM than patients with NICM.

Trial Registration

ClinicalTrials.gov Identifier: NCT01090362.

Pharmacological management of atrial fibrillation in patients with heart failure with reduced ejection fraction: review of current knowledge and future directions

Introduction: Both heart failure with reduced ejection fraction (HFrEF) and atrial fibrillation (AF) independently cause significant morbidity and mortality. The two conditions commonly coexist and AF in the setting of HFrEF is associated with worse mortality, hospitalizations, and quality of life compared to HFrEF without AF. Despite the large burden of these conditions, there is no clear optimal management strategy for when they occur together.Areas covered: This review focuses on the pharmacological management of AF in HFrEF. Studies were identified through PubMed search of relevant keywords. The authors review key clinical trials that have influenced management strategies and guidelines. The authors focus on the classes of drugs used to treat AF for both rate and rhythm control strategies including beta-blockers, digoxin, amiodarone, and dofetilide. Additionally, the authors discuss select non-antiarrhythmic medications that affect AF in HFrEF. The authors highlight the strengths and weakness of the data supporting the use of these medications and suggest future directions.Expert opinion: The pharmacological treatment of AF in HFrEF will need further refinement alongside the emerging role of catheter ablation. Novel HF medications and antiarrhythmics offer new tools to prevent the development of AF, as well as for rate and rhythm control strategies.

Ischemic Heart Disease Modifies the Association of Atrial Fibrillation With Mortality in Heart Failure With Reduced Ejection Fraction

Background

The CASTLE‐AF (Catheter Ablation versus Standard Conventional Therapy in Patients With Left Ventricular Dysfunction and Atrial Fibrillation) trial recently reported that catheter ablation of atrial fibrillation (AF) improves survival in heart failure (HF) with reduced ejection fraction (HFrEF). However, established AF was not associated with mortality in trials of contemporary HFrEF pharmacotherapies. We investigated whether HFrEF pathogenesis may influence the conclusions of studies evaluating the prognostic impact of AF.

Methods and Results

Using a prospective cohort study of 791 patients with HFrEF, with AF determined using 24‐hour ambulatory ECG monitoring, univariable and multivariable Cox regression analyses were used to define the association between AF and mode‐specific mortality (mean follow‐up of 5.4 years). One‐year HF‐related hospitalization was assessed with binary logistic regression analysis. One‐year cardiac remodeling was assessed in a subgroup (n=378) using echocardiography. AF was present in 28.2% of patients, with 9.4% of these being paroxysmal. While AF was associated with increased risk of all‐cause mortality (hazard ratio, 1.27; 95% confidence interval 1.03–1.57), with diverging survival curves after 1 year of follow‐up, this association was lost in age‐sex–adjusted analyses. However, AF was associated with increased risk of age‐sex–adjusted all‐cause mortality in people with ischemic pathogenesis, with a statistically significant interaction between pathogenesis and AF. This was predominantly attributed to progressive HF deaths. After 1 year, HF hospitalization and cardiac remodeling were not associated with AF, even in people with ischemic pathogenesis.

Conclusions

AF is associated with increased risk of death in HFrEF of ischemic pathogenesis, predominantly due to progressive HF deaths during long‐term follow‐up. HFrEF pathogenesis should be considered in trial design and interpretation.

Prognostic role of atrial fibrillation in patients affected by chronic heart failure. Data from the MECKI score research group

BACKGROUND

Atrial fibrillation (AF) is common in heart failure (HF). It is unclear whether AF has an independent prognostic role in HF. The aim of the present study was to assess the prognostic role of AF in HF patients with reduced ejection fraction (EF).

METHODS

HF patients were followed in 17 centers for 3.15years (1.51-5.24). Study endpoints were the composite of cardiovascular (CV) death and heart transplant (HTX) and all-cause death. Data analysis was performed considering the entire population and a 1 to 1 match between sinus rhythm (SR) and AF patients. Match process was done for age±5, gender, left ventricle EF±5, peakVO2±3 (ml/min/kg) and recruiting center.

RESULTS

A total of 3447 patients (SR=2882, AF=565) were included in the study. Considering the entire population, CV death and HTX occurred in 114 (20%) AF vs. 471 (16%) SR (p=0.026) and all-cause death in 130 (23%) AF vs. 554 (19.2%) SR patients (p=0.039). At univariable Cox analysis, AF was significantly related to prognosis. Applying a multivariable model based on all variables significant at univariable analysis (EF, peakVO2, ventilation/carbon dioxide relationship slope, sodium, kidney function, hemoglobin, beta-blockers and digoxin) AF was no longer associated with adverse outcomes. Matching procedure resulted in 338 couples. CV death and HTX occurred in 63 (18.6%) AF vs. 74 (21.9%) SR (p=0.293) and all-cause death in 71 (21%) AF vs. 80 (23.6%) SR (p=0.406), with no survival differences between groups.

CONCLUSION

In systolic HF AF is a marker of disease severity but not an independent prognostic indicator.

How does Chronic Atrial Fibrillation Influence Mortality in the Modern Treatment Era?

Atrial fibrillation (AF) continues to impose a significant burden upon healthcare resources. A sustained increase in the ageing population and better survival from conditions such as ischaemic heart disease have ensured that both the incidence and prevalence of AF continue to increase significantly. AF can lead to complications such as embolism and heart failure and these acting in concert with its associated co-morbidities portend increased mortality risk. Whilst some studies suggest that the mortality risk from AF is due to the "bad company it keeps" i.e. the associated co-morbidities rather than AF itself; undoubtedly some of the mortality is also due to the side-effects of various therapeutic strategies (anti-arrhythmic drugs, bleeding side-effects due to anti-coagulants or invasive procedures). Despite several treatment advances including newer anti-arrhythmic drugs and developments in catheter ablation, anti-coagulation remains the only effective means to reduce the mortality due to AF. Warfarin has been used as the oral anticoagulant in the treatment of AF for many years but suffers from disadvantages such as unpredictable INR levels, bleeding risks and need for haematological monitoring. This has therefore spurred a renewed interest in research and clinical studies directed towards developing safer and more efficacious anti-coagulants. We shall review in this article the epidemiological features of AF-related mortality from several studies as well as the cardiovascular and non-cardiac mortality mechanisms. We shall also elucidate why a rhythm control strategy has appeared to be counter-productive and attempt to predict the likely future impact of novel anti-coagulants upon mortality reduction in AF.

Atrial fibrillation in heart failure: The sword of Damocles revisited

Heart failure (HF) and atrial fibrillation (AF) frequently coexist and have emerged as major cardiovascular epidemics. There is growing evidence that AF is an independent prognostic marker in HF and affects patients with both reduced as well as preserved LV systolic function. There has been a general move in clinical practice from a rhythm control to a rate control strategy in HF patients with AF, although recent data suggests that rhythm control strategies may provide better outcomes in selected subgroups of HF patients. Furthermore, various therapeutic modalities including pace and ablate strategies with cardiac resynchronisation or radiofrequency ablation have become increasingly adopted, although their role in the management of AF in patients with HF remains uncertain. This article presents an overview of the multidimensional impact of AF in patients with HF. Relevant literature is highlighted and the effect of various therapeutic modalities on prognosis is discussed. Finally, while novel anticoagulants usher in a new era in thromboprophylaxis, research continues in a variety of new pathways including selective atrial anti-arrhythmic agents and genomic polymorphisms in AF with HF.

Atrial fibrillation in heart failure: an innocent bystander?

Heart failure (HF) and atrial fibrillation (AF) frequently coexist and each complicates the course of the other. The purpose of this review is to analyse the prognostic impact of AF in patients with HF and assess whether there is an advantage in targeting therapies towards the maintenance of sinus rhythm (SR) in this cohort of patients. The presence of AF in patients with HF has been reported to be independently associated with an increase in mortality in many studies and this increased risk is observed in those with both preserved and impaired LV systolic function. The optimal strategy for targeting AF in patients with HF is unclear but recent randomised controlled studies indicate no significant prognostic advantage associated with a rhythm control strategy as compared to a rate control strategy. A number of small studies have investigated the role of both cardiac resynchronization therapy (CRT) and AF catheter ablation for the maintenance of / conversion to SR in patients with HF with initial promising results although larger randomised controlled studies will need to be performed to define the role of these modalities in the treatment of this cohort and whether preliminary benefits observed in these studies translate to improvements in longer term prognosis. Finally, there has been a focus on modifying the arrhythmogenic atrial substrate and neurohormonal milieu by pharmacological means in order to prevent AF although it remains to be seen whether this approach proves to be efficacious with improvements in clinically relevant outcomes.

Irregular rhythm adversely influences calcium handling in ventricular myocardium: implications for the interaction between heart failure and atrial fibrillation

BACKGROUND

Despite adequate rate control, the combination of atrial fibrillation with heart failure (HF) has been shown, in a number of studies, to hasten HF progression. In this context, we aimed to test the hypothesis that an irregular ventricular rhythm causes an alteration in ventricular cardiomyocyte excitation-contraction coupling which contributes to the progression of HF.

METHODS AND RESULTS

We investigated the effects of electrical field stimulation (average frequency 2 Hz) in an irregular versus regular drive train pattern on the expression of calcium-handling genes and proteins in rat ventricular myocytes. The effect of rhythm on intracellular calcium transients was examined using Fura-2AM fluorescence spectroscopy. In conjunction, calcium-handling protein expression was examined in left ventricular samples obtained from end-stage HF patients, in patients with either persistent atrial fibrillation or sinus rhythm. Compared with regularly paced ventricular cardiomyocytes, in cells paced irregularly for 24 hours, there was a significant reduction in the expression of sarcoplasmic reticulum calcium (Ca(2+)) ATPase together with reduced serine-16 phosphorylation of phospholamban. These findings were accompanied by a 59% reduction (P<0.01) in the peak Ca2+ transient in irregulary paced myocytes compared with those with regular pacing. Consistent with these observations, we observed a 54% (P<0.05) decrease in sarcoplasmic reticulum Ca(2+)ATPase protein expression and an 85% (P<0.01) reduction in the extent of phosphorylation of phospholamban in the left ventricular myocardium of HF patients in atrial fibrillation compared with those in sinus rhythm.

CONCLUSIONS

Together, these data demonstrate that ventricular rhythmicity contributes significantly to excitation-contraction coupling by altering the expression and activity of key calcium-handling proteins. These data suggest that control of rhythm may be of benefit in patients with HF.

No impact of atrial fibrillation on mortality risk in optimally treated heart failure patients

BACKGROUND

Several studies have shown that atrial fibrillation (AF) is associated with increased risk of death in heart failure (HF) patients. However, it is not clear whether this increased risk is independent of other risk factors.

HYPOTHESIS

We hypothesized that AF would be an independent risk factor for death in a large cohort of HF patients.

METHODS

Patients referred to Norwegian HF outpatient clinics were enrolled between October 2000 and February 2008. Patients with heart rhythm other than AF or sinus rhythm were excluded. Mortality data were obtained from the National Statistics Bureau, Statistics Norway with the last update February 2008.

RESULTS

There were 4048 patients included in the analysis, with a median follow-up of 28 months. Adherence to guidelines regarding medical treatment was high. In univariate analysis, AF patients (n = 1391) had a higher risk of death than patients in sinus rhythm (n = 2657) (hazard ratio [HR] 1.181; 95% confidence interval (CI), 1.044-1.336; P = 0.008). However, after adjusting for confounding factors (age, New York Heart Association class, coronary artery disease as the main cause of HF, use of any loop diuretic, hemoglobin level, and serum creatinine), AF was no longer associated with increased risk of death (HR 1.037; 95% CI, 0.901-1.193; P = 0.619).

CONCLUSIONS

In this cohort of heart failure patients receiving optimal medical treatment at specialized HF clinics, AF was not associated with increased risk of death after adjusting for confounding factors.