Claire T. Than

Atrial Fibrillation Burden and Short-Term Risk of Stroke: Case-Crossover Analysis of Continuously Recorded Heart Rhythm From Cardiac Electronic Implanted Devices

Background—The temporal relationship of atrial fibrillation (AF) and stroke risk is controversial. We evaluated this relationship via a case-crossover analysis of ischemic strokes in a large cohort of patients with cardiac implantable electronic devices. Methods and Results—We identified 9850 patients with cardiac implantable electronic devices remotely monitored in the Veterans Administration Health Care System between 2002 and 2012. There were 187 patients with acute ischemic stroke and continuous heart rhythm monitoring for 120 days before the stroke (age, 69±8.4 years; 98% with an implantable defibrillator). We compared each patient’s daily AF burden in the 30 days before stroke (case period) with their AF burden during days 91 to 120 pre stroke (control period). Defining positive AF burden as ≥5.5 hours of AF on any given day, 156 patients (83%) had no positive AF burden in both periods and, in fact, had little to no AF; 15 (8%) patients had positive AF burden in both periods. Among the discordant (informative) patients, 13 exceeded 5.5 hours of AF in the case period but not in the control period, whereas 3 had positive AF burden in the control but not in the case period (warfarin-adjusted odds ratio for stroke, 4.2; 95% confidence interval, 1.5–13.4). Odds ratio for stroke was highest (17.4; 95% confidence interval, 5.39–73.1) in the 5 days immediately after a qualifying occurrence of AF and decreased toward 1.0 as the period after the AF occurrence increased beyond 30 days. Conclusions—In this population with continuous heart rhythm recording, multiple hours of AF had a strong but transient effect raising stroke risk.

Differences and trends in stroke prevention anticoagulation in primary care vs cardiology specialty management of new atrial fibrillation: The Retrospective Evaluation and Assessment of Therapies in AF (TREAT-AF) study.

BACKGROUND Atrial fibrillation and flutter (AF, collectively) cause stroke. We evaluated whether treating specialty influences warfarin prescription in patients with newly diagnosed AF. METHODS In the TREAT-AF study, we used Veterans Health Administration health record and claims data to identify patients with newly diagnosed AF between October 2004 and November 2008 and at least 1 internal medicine/primary care or cardiology outpatient encounter within 90 days after diagnosis. The primary outcome was prescription of warfarin. RESULTS In 141,642 patients meeting the inclusion criteria, the mean age was 72.3 ± 10.2 years, 1.48% were women, and 25.8% had cardiology outpatient care. Cardiology-treated patients had more comorbidities and higher mean CHADS2 scores (1.8 vs 1.6, P < .0001). Warfarin use was higher in cardiology-treated vs primary care only-treated patients (68.6% vs 48.9%, P < .0001). After covariate and site-level adjustment, cardiology care was significantly associated with warfarin use (odds ratio [OR] 2.05, 95% CI 1.99-2.11). These findings were consistent across a series of adjusted models (OR 2.05-2.20), propensity matching (OR 1.98), and subgroup analyses (OR 1.58-2.11). Warfarin use in primary-care-only patients declined from 2004 to 2008 (51.6%-44.0%, P < .0001), whereas the adjusted odds of warfarin receipt with cardiology care (vs primary care) increased from 2004 to 2008 (1.88-2.24, P < .0001). CONCLUSION In patients with newly diagnosed AF, we found large differences in anticoagulation use by treating specialty. A divergent 5-year trend of risk-adjusted warfarin use was observed. Treating specialty influences stroke prevention care and may impact clinical outcomes.

Feasibility of Extended Ambulatory Electrocardiogram Monitoring to Identify Silent Atrial Fibrillation in High‐risk Patients: The Screening Study for Undiagnosed Atrial Fibrillation (STUDY‐AF)

Identification of silent atrial fibrillation (AF) could prevent stroke and other sequelae.

Warfarin utilisation and anticoagulation control in patients with atrial fibrillation and chronic kidney disease.

Objective To evaluate warfarin prescription, quality of international normalised ratio (INR) monitoring and of INR control in patients with atrial fibrillation (AF) and chronic kidney disease (CKD). Methods We performed a retrospective cohort study of patients with newly diagnosed AF in the Veterans Administration (VA) healthcare system. We evaluated anticoagulation prescription, INR monitoring intensity and time in and outside INR therapeutic range (TTR) stratified by CKD. Results Of 123 188 patients with newly diagnosed AF, use of warfarin decreased with increasing severity of CKD (57.2%–46.4%), although it was higher among patients on dialysis (62.3%). Although INR monitoring intensity was similar across CKD strata, the proportion with TTR≥60% decreased with CKD severity, with only 21% of patients on dialysis achieving TTR≥60%. After multivariate adjustment, the magnitude of TTR reduction increased with CKD severity. Patients on dialysis had the highest time markedly out of range with INR <1.5 or >3.5 (30%); 12% of INR time was >3.5, and low TTR persisted for up to 3 years. Conclusions There is a wide variation in anticoagulation prescription based on CKD severity. Patients with moderate-to-severe CKD, including dialysis, have substantially reduced TTR, despite comparable INR monitoring intensity. These findings have implications for more intensive warfarin management strategies in CKD or alternative therapies such as direct oral anticoagulants.

Gender Differences in Clinical Outcomes After Catheter Ablation of Atrial Fibrillation

Objective To explore gender differences in real-world outcomes after catheter ablation of atrial fibrillation (AF). Background Compared to men, women with AF have greater thromboembolic risk and tend to be more symptomatic. Catheter ablation is generally more effective than antiarrhythmic drug therapy alone. However, there is limited data on the influence of gender on AF ablation outcomes. Methods We analyzed medical claims of 45 million United States patients enrolled in a variety of employee-sponsored and fee-for-service plans. We identified patients who underwent an AF ablation from 2007 to 2011 and evaluated 30-day safety and one-year effectiveness outcomes. Results Of the 21,091 patients who underwent an AF ablation, 7,460 (29%) were female. Women, compared to men, were older (62±11 vs. 58±11 years), had higher CHADS2 (1.2±1.1 vs. 1.0±1.0), higher CHA2DS2-VASc (2.9±1.5 vs. 1.6±1.4), and higher Charlson comorbidity index scores (1.2±1.3 vs. 1.0±1.2)(p<0.001 for all). Following ablation, women had higher risk of 30-day complications of hemorrhage (2.7 vs. 2.0%,p<0.001) and tamponade (3.8 vs. 2.9%,p<0.001). In multivariable analyses, women were more likely to have a re-hospitalization for AF (adjusted HR 1.12,p=0.009), but less likely to have repeat AF ablation (adjusted HR 0.92,p=0.04) or cardioversion (adjusted HR 0.75,p<0.001). Conclusion Women have increased hospitalization rates after AF ablation and are more likely to have a procedural complication. Despite the higher rate of hospital admissions for AF after ablation, women were less likely to undergo repeat ablation or cardioversion. These data call for greater examination of barriers and facilitators to sustain rhythm control strategies in women.

Safety and Clinical Outcomes of Catheter Ablation of Atrial Fibrillation in Patients with Chronic Kidney Disease

Data regarding catheter ablation of atrial fibrillation (AF) in patients with chronic kidney disease (CKD) is limited. We therefore assessed the association of CKD with common safety and clinical outcomes in a nationwide sample of ablation recipients.

Amiodarone and risk of death in contemporary patients with atrial fibrillation: Findings from The Retrospective Evaluation and Assessment of Therapies in AF study

BACKGROUND There are limited data on mortality outcomes associated with use of amiodarone in atrial fibrillation and flutter (AF). METHODS We evaluated the association of amiodarone use with mortality in patients with newly diagnosed AF using complete data from the Department of Veterans Affairs national health care system. We included patients seen in an outpatient setting within 90 days of a new diagnosis for nonvalvular AF between Veterans Affairs fiscal years 2004 and 2008. Multivariate analysis and propensity-matched Cox proportional hazards regression were used to evaluate the association of amiodarone use to death. RESULTS Of 122,465 patients (353,168 person-years of follow-up, age 72.1 ± 10.3 years, 98.4% males), amiodarone was prescribed in 11,655 (9.5%). Cumulative, unadjusted mortality rates were higher for amiodarone recipients than for nonrecipients (87 vs 73 per 1,000 person-years, P < .001). However, in multivariate and propensity-matched survival analyses, there was no significant difference in mortality (multivariate hazard ratio 1.01, 95% CI 0.97-1.05, P = .51, and propensity-matched hazard ratio 1.02, 95% CI 0.97-1.07, P = .45). The hazard of death was not modified by age, sex, heart failure, kidney function, β-blocker use, or warfarin use, but there was evidence of effect modification among patients diagnosed with AF as an inpatient versus outpatient. CONCLUSION In a national health care system population of newly diagnosed AF, overall use of amiodarone as an early treatment strategy was not associated with mortality.

Impact of Baseline Stroke Risk and Bleeding Risk on Warfarin International Normalized Ratio Control in Atrial Fibrillation (from the TREAT-AF Study)

Warfarin prevents stroke and prolongs survival in patients with atrial fibrillation and flutter (AF, collectively) but can cause hemorrhage. The time in international normalized ratio (INR) therapeutic range (TTR) mediates stroke reduction and bleeding risk. This study sought to determine the relation between baseline stroke, bleeding risk, and TTR. Using data from The Retrospective Evaluation and Assessment of Therapies in Atrial Fibrillation (TREAT-AF) retrospective cohort study, national Veterans Health Administration records were used to identify patients with newly diagnosed AF from 2003 to 2012 and subsequent initiation of warfarin. Baseline stroke and bleeding risk was determined by calculating CHA2DS2-VASc and HAS-BLED scores, respectively. Main outcomes were first-year and long-term TTR and INR monitoring rate. In 167,190 patients, the proportion of patients with TTR (>65%) decreased across increasing strata of CHA2DS2-VASc and HAS-BLED. After covariate adjustment, odds of achieving TTR >65% were significantly associated with high CHA2DS2-VASc or HAS-BLED score. INR monitoring rate was similar across risk strata. In conclusion, increased baseline stroke and bleeding risk is associated with poor INR control, despite similar rates of INR monitoring. These findings may paradoxically limit warfarins efficacy and safety in high-risk patients and may explain observed increased bleeding and stroke rates in this cohort.