Fibroblast growth factor-23 and incident atrial fibrillation: the Multi-Ethnic Study of Atherosclerosis (MESA) and the Cardiovascular Health Study (CHS).

BACKGROUND: Fibroblast growth factor-23 (FGF-23) is a hormone that promotes urinary phosphate excretion and regulates vitamin D metabolism. Circulating FGF-23 concentrations increase markedly in chronic kidney disease and are associated with increased risk of clinical cardiovascular events. FGF-23 may promote atrial fibrillation (AF) by inducing left ventricular hypertrophy and diastolic and left atrial dysfunction. METHODS AND RESULTS: We tested the associations of circulating FGF-23 concentration with incident AF among 6398 participants in the Multi-Ethnic Study of Atherosclerosis (MESA) and 1350 participants in the Cardiovascular Health Study (CHS), all free of clinical cardiovascular disease at baseline. Over a median of 7.7 and 8.0 years of follow-up, we observed 291 and 229 incident AF events in MESA and CHS, respectively. In multivariable Cox proportional hazards models, each 2-fold-higher FGF-23 concentration was associated with a 41% higher risk of incident AF in MESA (hazard ratio, 1.41; 95% confidence interval, 1.13-1.76; P=0.003) and a 30% higher risk of incident AF in CHS (hazard ratio, 1.30; 95% confidence interval, 1.05-1.61; P=0.016) after adjustment for potential confounding characteristics, including kidney disease. Serum phosphate concentration was significantly associated with incident AF in MESA (hazard ratio, 1.15 per 0.5 mg/dL; 95% confidence interval, 1.02-1.31; P=0.023) but not CHS. In MESA, an association of low estimated glomerular filtration rate with incident AF was partially attenuated by adjustment for FGF-23. CONCLUSION: Higher circulating FGF-23 concentration is associated with incident AF and may, in part, explain the link between chronic kidney disease and AF.

Atrial Fibrillation in Heart Failure US Ambulatory Cardiology Practices and the Potential for Uptake of Catheter Ablation: An National Cardiovascular Data Registry (NCDR®) Research to Practice (R2P) Project.

BACKGROUND: Atrial fibrillation (AF) and heart failure with reduced ejection fraction frequently coexist. The AATAC (Ablation versus Amiodarone for Treatment of persistent Atrial fibrillation in patients with Congestive heart failure and an implantable device) trial suggests that catheter ablation may benefit these patients. However, applicability to contemporary ambulatory cardiology practice is unknown. METHODS AND RESULTS: Using the outpatient National Cardiovascular Data Registry® Practice Innovation and Clinical Excellence Registry, we identified participants meeting AATAC enrollment criteria between 2013 and 2014. Treatment with medications and procedures was assessed at registry inclusion. From 164 166 patients with AF and heart failure, 8483 (7%) patients potentially met AATAC inclusion criteria. Eligible subjects, compared to AATAC trial participants, were older (mean age, 71.2±11.4 years) and had greater comorbidity (coronary artery disease 79.2%, hypertension 82.4%, and diabetes mellitus 31.8%). AF was predominantly paroxysmal (65.5%), rather than persistent/permanent (16.7%) or new onset (17.8%), whereas all patients in the AATAC trial had persistent AF. Commonly used atrioventricular-nodal blocking agents were carvedilol (71.2%), digoxin (31.9%), and metoprolol (27.1%). Rhythm control with anti-arrhythmic drugs was reported in 29.0% of AATAC eligible patients (predominantly amiodarone [24.6%]) and 9.3% had undergone catheter ablation. Patients who underwent ablation were more likely to be younger and have less comorbidities than those who did not. CONCLUSIONS: Among the contemporary ambulatory AF/heart failure with reduced ejection fraction population, treatment is predominantly rate control with few catheter ablations. Application of AATAC findings has the potential to markedly increase the use of catheter ablation in this population, although significant differences in clinical profiles might influence ablation outcomes in practice.

Outcomes Among Older Patients Receiving Implantable Cardioverter-Defibrillators for Secondary Prevention: From the NCDR ICD Registry.

BACKGROUND: Clinical trials of implantable cardioverter-defibrillators (ICDs) for secondary prevention of sudden cardiac death were conducted nearly 2 decades ago and enrolled few older patients. OBJECTIVES: This study assessed morbidity and mortality of older patients receiving ICDs for secondary prevention in contemporary clinical practice. METHODS: We identified 12,420 Medicare beneficiaries from the National Cardiovascular Data Registry ICD Registry undergoing first-time secondary prevention ICD implantation between 2006 and 2009 in 956 U.S. hospitals. Risks of death, hospitalization, and admission to a skilled nursing facility (SNF) were assessed over 2 years in age strata (65 to 69, 70 to 74, 75 to 79, and ≥80 years of age) using Medicare claims. The adjusted association between age and outcomes was evaluated using multivariable models. RESULTS: The mean age was 75 years at the time of implantation; 25.3% were <70 years of age and 25.7% were ≥80 years of age. Overall, the risk of death at 2 years was 21.8%, ranging from 14.7% among those <70 years of age to 28.9% among those ≥80 years of age (adjusted risk ratio [aRR]: 2.01; 95% confidence interval [CI]: 1.85 to 2.33; p for trend <0.001). The cumulative incidence of hospitalizations was 65.4%, ranging from 60.5% in those <70 years of age to 71.5% in those ≥80 years of age (aRR: 1.27; 95% CI: 1.19 to 1.36; p for trend <0.001). The cumulative incidence of admission to a SNF ranged from 13.1% among those <70 years of age to 31.9% among those ≥80 years of age (aRR: 2.67; 95% CI: 2.37 to 3.01; p for trend <0.001); SNF admission risk was highest in the first 30 days. CONCLUSIONS: Almost 4 in 5 older patients receiving a secondary prevention ICD survives at least 2 years. High hospitalization and SNF admission rates, particularly among the oldest patients, identify substantial care needs after device implantation.