Index and Repeat Ablation for Atrial Fibrillation in Older versus Younger Patients: A Propensity-Score Matching Analysis

Catheter ablation is a well-established rhythm control therapy in atrial fibrillation (AF). Although the prevalence of AF increases dramatically with age, the prognosis and safety profile of index and repeat ablation procedures remain unclear in the older population. The primary endpoint of this study was to assess the arrhythmia recurrence, reablation and complication rates in older patients. Secondary endpoints were the identification of independent predictors of arrhythmia recurrence and reablation, including information on pulmonary vein (PV) reconnection and other atrial foci. Older (n=129, ≥70 years) and younger (n=129, <70 years) patients were compared using a propensity-score matching analysis based on age, gender, obesity, hypertension, dyslipidemia, diabetes mellitus, dilated left atrium, severe obstructive sleep apnea, cardiac disease, left systolic ventricular function, AF pattern and ablation technique. Arrhythmia recurrence and reablation were evaluated in both groups using a Cox regression analysis in order to identify predictors. During a 30-month follow-up period, there were no significant differences between older and younger patients in the arrhythmia-free survival (65.1% and 59.7%; log-rank test p=0.403) and complication (10.1% and 10.9%; p>0.999) rates after the index ablation. However, the reablation rate was significantly different (46.7% and 69.2%; p<0.05, respectively). In those patients who underwent reablation procedure (redo subgroups), there were no differences in the incidence of PV reconnection (38.1% redo-older and 27.8% redo-younger patients; p=0.556). However, the redo-older patients had lower reconnected PVs per patient (p<0.01) and lower atrial foci (2.3 and 3.7; p<0.01) than the redo-younger patients. A further important finding was that age was not an independent predictor of arrhythmia recurrence or reablation. Our data reveal that the AF index ablation in older patients had a similar efficacy and safety profile to younger patients. Therefore, age alone must not be considered a prognostic factor for AF ablation but the presence of limiting factors such as frailty and multiple comorbidities.

Genetics of height and risk of atrial fibrillation: A Mendelian randomization study

BACKGROUND

Observational studies have identified height as a strong risk factor for atrial fibrillation, but this finding may be limited by residual confounding. We aimed to examine genetic variation in height within the Mendelian randomization (MR) framework to determine whether height has a causal effect on risk of atrial fibrillation.

METHODS AND FINDINGS

In summary-level analyses, MR was performed using summary statistics from genome-wide association studies of height (GIANT/UK Biobank; 693,529 individuals) and atrial fibrillation (AFGen; 65,446 cases and 522,744 controls), finding that each 1-SD increase in genetically predicted height increased the odds of atrial fibrillation (odds ratio [OR] 1.34; 95% CI 1.29 to 1.40; p = 5 × 10-42). This result remained consistent in sensitivity analyses with MR methods that make different assumptions about the presence of pleiotropy, and when accounting for the effects of traditional cardiovascular risk factors on atrial fibrillation. Individual-level phenome-wide association studies of height and a height genetic risk score were performed among 6,567 European-ancestry participants of the Penn Medicine Biobank (median age at enrollment 63 years, interquartile range 55-72; 38% female; recruitment 2008-2015), confirming prior observational associations between height and atrial fibrillation. Individual-level MR confirmed that each 1-SD increase in height increased the odds of atrial fibrillation, including adjustment for clinical and echocardiographic confounders (OR 1.89; 95% CI 1.50 to 2.40; p = 0.007). The main limitations of this study include potential bias from pleiotropic effects of genetic variants, and lack of generalizability of individual-level findings to non-European populations.

CONCLUSIONS

In this study, we observed evidence that height is likely a positive causal risk factor for atrial fibrillation. Further study is needed to determine whether risk prediction tools including height or anthropometric risk factors can be used to improve screening and primary prevention of atrial fibrillation, and whether biological pathways involved in height may offer new targets for treatment of atrial fibrillation.

Clinical Factors Associated with a Successful Catheter Ablation Outcome in Elderly Patients with Atrial Fibrillation

Catheter ablation is currently an established treatment for symptomatic paroxysmal atrial fibrillation (AF). We focused on elderly patients with a high prevalence of AF and attempted to identify the clinical factors associated with unsuccessful ablation outcomes.Among 735 consecutive patients who underwent AF ablation procedures, 108 (14.7%, 66 men) aged ≥ 75 years were included. Of them, 80 had paroxysmal AF, and the remaining 28 non-paroxysmal AF. All patients underwent pulmonary vein (PV) isolation and occasionally additional ablation. When AF recurred, redo ablation procedures were performed if the patient so desired.The mean number of ablation procedures was 1.1 ± 0.4 times per patient. During a mean follow-up of 38.7 ± 21.7 months, sinus rhythm was maintained in 100 patients (92.6%) without any antiarrhythmic drugs, but not in the remaining 8 (7.4%). Left atrial diameter (LAD, P < 0.001), left ventricular (LV) systolic diameter (P < 0.001), LV diastolic diameter (P = 0.001), non-PV AF foci (P = 0.036), and diabetes (P = 0.045) were associated with unsuccessful ablation procedures. Multivariate logistic regression analysis revealed a large LAD and non-PV AF foci were significant independent predictors of AF recurrences, with odds ratios of 0.76 (P = 0.019) and 0.04 (P = 0.023), respectively. In a total of 124 procedures, one major (0.8%) and 11 minor (8.9%) complications occurred.In elderly AF patients, catheter ablation of AF is effective and safe. Non-PV AF foci and a large LAD were independent clinical predictors of unsuccessful AF ablation outcomes.

Height is associated with incident atrial fibrillation in a large Asian cohort

BACKGROUND

Although increased height is associated with a risk of atrial fibrillation (AF), the mechanism is not well understood. We aimed to explore whether this association varies with metabolic conditions.

METHODS AND RESULTS

We used the database from the 14-year Korea National Health Insurance Service-National Sample Cohort. The data of 368,206 adults older than 20 years who received a health check-up were analyzed to explore the association of height and AF risk. Cox proportional hazards regression models were used to compute hazard ratios (HRs) and 95% confidence intervals (CIs) for associations of height with the risk of AF. During the median follow up duration of 8.46 years, 2641 (0.72%) patients were diagnosed with AF at 3,070,724 person-years. Overall, greater height was significantly associated with AF risk (HR per 5 cm, 1.22; 95% CI, 1.03-1.05). The association did not vary with age, sex, obesity, hypertension, and diabetes.

CONCLUSION

Metabolic conditions do not affect the higher risk of AF in tall people.

Obesity is associated with incident atrial fibrillation independent of gender: A meta-analysis

BACKGROUND

The prevalence of obesity is increasing among the general population. Obesity is associated with increased risk of several cardiovascular conditions, which in turn may increase the risk for atrial fibrillation (AF). We performed a meta-analysis of cohort studies that examined the effect of obesity on the incidence of AF. In addition, we examined the effect of obesity on the incidence of AF stratified by gender.

METHODS AND RESULTS

We searched the MEDLINE and EMBASE databases for studies evaluating the effect of obesity on AF. Pooled risk ratios (RR) with 95% confidence intervals (CI) were calculated using a random effects model. Sixteen trials involving 587,372 subjects were included in the analysis. Obesity was defined as body mass index >30 kg/m² . AF during follow-up developed in 5,751 of 91,031 (6.3%) obese subjects and in 15,346 of 496,341 (3.1%) nonobese subjects (RR = 1.51, 95% CI 1.35 to 1.68; P < 0.00001). Based on the pooled estimate across the studies, the effect of obesity on incident AF was similar in men (RR = 1.41, 95% 1.24 to 1.62; P < 0.00001) and women (RR = 1.53, 95% CI 1.19 to 1.97; P < 0.00001).

CONCLUSION

Obesity is associated with an increased risk of new-onset AF in susceptible individuals. This effect appears to be consistent in both genders. Further studies are warranted to examine the impact of weight loss interventions on the risk of developing AF.

Prevalence, incidence, and lifetime risk of atrial fibrillation in China: new insights into the global burden of atrial fibrillation

BACKGROUND

Much of the epidemiology of atrial fibrillation (AF) is based on data from Western populations. Despite the huge population of Asia, data on the clinical epidemiology of AF in Asian countries are limited. The current study aimed to investigate the prevalence and incidence of newly diagnosed (ie, incident) AF, as well as lifetime risk, in China and to determine the clinical risk factors contributing to its development.

METHODS

Using a medical insurance database involving > 10 million individuals for the years 2001 to 2012 in the southwest of China, trends in incident AF were calculated using Kaplan-Meier analysis and Cox regression. The usefulness of the CHADS2 (congestive heart failure, hypertension, age, diabetes, stroke [doubled]) and CHA2DS2-VASc (congestive heart failure, hypertension, age ≥ 75 [doubled], diabetes, stroke [doubled], vascular disease, age 65-74, and sex category [female]) scores was tested in predicting the occurrence of incident AF.

RESULTS

A total of 471,446 individuals (aged ≥ 20 years) were studied, with 1,924,975 person-years of experience. We identified 921 patients with incident AF (62% male; mean age, 62 years). The prevalence of incident AF in subjects aged ≥ 20 years was 0.2 per 100 people, with an incidence of AF of 0.05 per 100 person-years overall. Over an 11-year period, the prevalence of AF increased 20-fold, whereas AF-related stroke increased 13-fold. The lifetime risk of AF was approximately one in five among Chinese adults, and it increased with advancing age. The CHA2DS2-VASc score was superior to the CHADS2 score in predicting the risk of incident AF in our Chinese population (DeLong test, Z = 6.621, P < .001).

CONCLUSIONS

The AF burden, as well as the risk of AF-related stroke, has increased significantly over the past 11 years in the southwest of China. The public health burden of AF and its complications are greatest in the very elderly, with major implications for health-care systems given the global burden of this common arrhythmia.

Genetic variants related to height and risk of atrial fibrillation: the cardiovascular health study

Increased height is a known independent risk factor for atrial fibrillation (AF). However, whether genetic determinants of height influence risk is uncertain. In this candidate gene study, we examined the association of 209 height-associated single-nucleotide polymorphisms (SNPs) with incident AF in 3,309 persons of European descent from the Cardiovascular Health Study, a prospective cohort study of older adults (aged ≥ 65 years) enrolled in 1989-1990. After a median follow-up period of 13.2 years, 879 participants developed incident AF. The height-associated SNPs together explained approximately 10% of the variation in height (P = 6.0 × 10(-8)). Using an unweighted genetic height score, we found a nonsignificant association with risk of AF (per allele, hazard ratio = 1.01, 95% confidence interval: 1.00, 1.02; P = 0.06). In weighted analyses, we found that genetically predicted height was strongly associated with AF risk (per 10 cm, hazard ratio = 1.30, 95% confidence interval: 1.03, 1.64; P = 0.03). Importantly, for all models, the inclusion of actual height completely attenuated the genetic height effect. Finally, we identified 1 nonsynonymous SNP (rs1046934) that was independently associated with AF and may warrant future study. In conclusion, we found that genetic determinants of height appear to increase the risk of AF, primarily via height itself. This approach of examining SNPs associated with an intermediate phenotype should be considered as a method for identifying novel genetic targets.

Coronary artery diseases in Japanese patients with nonvalvular atrial fibrillation

BACKGROUND

Both the prevalence of atrial fibrillation and coronary artery disease (CAD) is increasing in aged societies. However, limited data are available regarding the prevalence of CAD and the incidence of coronary events in Japanese patients with nonvalvular atrial fibrillation (NVAF).

METHODS AND RESULTS

The data in this study were derived from Shinken Database 2004-2010, which includes 15,227 new patient visitors to the Cardiovascular Institute between June 2004 and March 2011. In the database, 1835 patients were diagnosed with NVAF (mean age 63 years, mean CHADS2 score 1.1 ± 1.1, and 75% were men). The prevalence of CAD at the initial visit was 118 patients (6.4%). They were older age and had a greater prevalence of men, more history of congestive heart failure and more history of cardiovascular risk factors rather than those without. During the follow-up period of 532 ± 599 days, coronary events (myocardial infarction, unstable angina, and stable angina) occurred in 51 patients (1.9%/year). Multivariate analysis showed that a history of CAD (p<0.001) and older age (p=0.024) were independent predictors of the incidence of future coronary events.

CONCLUSIONS

In Japanese patients with NVAF, both the presence of CAD and the occurrence of coronary events are not uncommon. History of CAD and older age are strongly associated with the incidence of coronary events.

The global burden of atrial fibrillation and stroke: a systematic review of the epidemiology of atrial fibrillation in regions outside North America and Europe

BACKGROUND

Although atrial fibrillation (AF) is accepted as the most common sustained cardiac arrhythmia, most published epidemiologic studies focus on predominantly white populations in North America or Europe, and information on AF in nonwhite populations is scarce. The objective of this study was to undertake a systematic review of the published literature on the epidemiology of AF in other regions.

METHODS

Systematic literature searches (MEDLINE; 1990-2010) identified epidemiologic studies reporting on the prevalence or incidence of AF, stroke in AF, risk factors for AF, or the use of antithrombotic therapy in countries outside North America and Europe. This report presents a descriptive analysis of the data; no meta-analysis was planned.

RESULTS

Many of the 38 articles identified were from the Far East, although Australia, New Zealand, the Middle East, and South America were also represented. The reported prevalence of AF varied among countries, with different ranges in community- and hospital-based studies (0.1%-4% and 2.8%-14%, respectively). The use of anticoagulant therapy varied widely among countries and studies, as did the reported prevalence of stroke in patients with AF (2.8%-24.2%).

CONCLUSIONS

High-quality epidemiologic studies are clearly required to improve understanding of the worldwide burden of AF and stroke in AF. Major improvements in the provision of thromboprophylaxis are also needed in many countries, given the high proportion of untreated patients who are, hence, at risk of stroke.

The impact of height on the risk of atrial fibrillation: the Cardiovascular Health Study

AIMS

Atrial fibrillation (AF) is the most common sustained arrhythmia. Increased body size has been associated with AF, but the relationship is not well understood. In this study, we examined the effect of increased height on the risk of AF and explore potential mediators and implications for clinical practice.

METHODS AND RESULTS

We examined data from 5860 individuals taking part in the Cardiovascular Health Study, a cohort study of older US adults followed for a median of 13.6 (women) and 10.3 years (men). Multivariate linear models and age-stratified Cox proportional hazards and risk models were used, with focus on the effect of height on both prevalent and incident AF. Among 684 (22.6%) and 568 (27.1%) incident cases in women and men, respectively, greater height was significantly associated with AF risk [hazard ratio (HR)(women) per 10 cm 1.32, confidence interval (CI) 1.16-1.50, P < 0.0001; HR(men) per 10 cm 1.26, CI 1.11-1.44, P < 0.0001]. The association was such that the incremental risk from sex was completely attenuated by the inclusion of height (for men, HR 1.48, CI 1.32-1.65, without height, and HR 0.94, CI 0.85-1.20, with height included). Inclusion of height in the Framingham model for incident AF improved discrimination. In sequential models, however, we found minimal attenuation of the risk estimates for AF with adjustment for left ventricular (LV) mass and left atrial (LA) dimension. The associations of LA and LV size measurements with AF risk were weakened when indexed to height.

CONCLUSION

Independent from sex, increased height is significantly associated with the risk of AF.

Gender-specific relationship between serum uric acid level and atrial fibrillation prevalence

BACKGROUND

Although various kinds of cardiovascular risk factors have been reported to be associated with atrial fibrillation (AF), the relationship between serum uric acid level and AF has not been fully examined.

METHODS AND RESULTS

Data were collected from a single hospital-based cohort in the Shinken Database 2004-2008 (n=11,123), and consisted of serum uric acid level for 7,155 patients. The association between serum uric acid level and AF prevalence was evaluated on logistic regression. Uric acid significantly increased the crude AF prevalence in both men and women (both, P<0.001). The odds ratio (OR) and 95% confidence interval (95%CI) in the highest tertile compared with the lowest one were 3.368 (2.478-4.578) and 1.408 (1.169-1.695) in women and men, respectively. Uric acid was also significantly associated with other various cardiovascular risk factors for AF. Even after the multivariate model was adjusted using these variables, the effect of uric acid on AF was independent in women (OR, 1.888; 95%CI: 1.278-2.790), but not in men.

CONCLUSIONS

Reflecting the composite of various cardiovascular risk factors, serum uric acid level was apparently associated with AF prevalence. The independent association in women might imply some sex-specific mechanisms. The results should be confirmed in prospective studies.

Radiofrequency ablation for treatment of atrial fibrillation

INTRODUCTION

Atrial Fibrillation (AF) is the most common cardiac arrhythmia which represents a major public health problem. The main purpose of this research is to evaluate the Radiofrequency (RF) ablation effects in the patients with chronic AF scheduled for cardiac surgery because of different heart diseases.

METHODS

The descriptive and prospective study was conducted on 60 patients with AF scheduled for surgery along with RF ablation. The data were collected by questionnaire and included: patients' age, sex, NYHA class, operation type, past medical history, type and cause of valvular heart disease, preoperative ECG (electrocardiogram), duration of surgery, clamping time, cardiopulmonary bypass, and RF ablation time. RF ablation was followed by the main operation. The follow up examination, ECG, and echocardiography were performed 3 and 6 months after operation.

RESULTS

The mean age of patients was 48±10 years (18-71 years). Forty one patients had permanent AF and 19 had the persistent AF. The left ventricular ejection fraction was 48.27±9.75 percent before operation, and reached to 56.27±7.87 percent after the surgery (P<0.001). The mean NYHA class before the surgery was 2.83±0.68 which decreased to 1.34±0.46 6 months after the surgery with RF ablation (P<0.001). One patient (1.6%) died after surgery. Complete relief and freedom from AF recurrence was observed in 70% of patients in the mean follow up in 7 months after the surgery. The sinus rhythm with efficient atrial contraction was established in 100% of discharged patients.

CONCLUSION

RF ablation is an effective procedure to cure atrial fibrillation in patients undergoing cardiac surgeries.

Recent mortality of Japanese patients with atrial fibrillation in an urban city of Tokyo

BACKGROUND

In Japan, the recent status of the mortality of atrial fibrillation (AF) patients is still unclear.

METHODS AND RESULTS

We used a single-hospital based cohort database in an urban city (Tokyo) in Japan, including all the new visitors from 2004 to 2009 (n=13,228). The non-adjusted death rates of AF patients for all-cause, stroke, and cardiovascular death were 1091, 97, and 727 per 100,000 patient-years, and the age-adjusted ones were 317 (95% CI, 316-318), 16 (95% CI, 16-16), and 238 (95% CI, 237-239), respectively. The age-adjusted relative risk of AF on all-cause mortality was 1.7 in the particular population.

CONCLUSIONS

The present study provides the most recent data about the characteristics and the mortality of AF patients in Tokyo, thus serving as the basic information for finding problems to solve regarding Japanese AF patients.