Alexander Mazur

Bleeding Rates in Veterans Affairs Patients with Atrial Fibrillation Who Switch from Warfarin to Dabigatran

OBJECTIVESnClinical trial data suggest that dabigatran and warfarin have similar rates of major bleeding but higher rates of gastrointestinal bleeding. These findings have not been evaluated outside of a clinical trial. We evaluated the relative risks of any, gastrointestinal, intracranial, and other bleeding for Veterans Affairs patients who switched to dabigatran after at least 6 months on warfarin, compared with patients who continued on warfarin.nnnMETHODSnWe used national Veterans Affairs administrative encounter and pharmacy data from fiscal years 2010-2012 to identify 85,344 patients with atrial fibrillation who had been taking warfarin for at least 180 days before June 2011, of whom 1394 (1.7%) received dabigatran (150 mg) during the next 15 months. Dates of the first occurrence of each type of bleed and dates of death from June 2011 to September 2012 were determined. Baseline and time-dependent patient characteristics were identified, including comorbid conditions, stroke and bleeding risk scores, and time in therapeutic range for international normalized ratios. Marginal structural models were used to address selection bias in the longitudinal observational data. Weighted logistic regression models were fit using generalized estimating equations and reflected baseline and time-dependent covariates and weekly indicators of anticoagulant type (warfarin or dabigatran).nnnRESULTSnCompared with patients who never used dabigatran, patients who used dabigatran at least once were younger, were more likely to be white, had lower international normalized ratio time in therapeutic range on warfarin, had lower stroke risk scores, and had similar bleeding risk scores. Overall, 10,734 patients experienced bleeding events, including 131 events after dabigatran use. The risk-adjusted rate of any bleeding was higher with dabigatran compared with warfarin, which was largely driven by a 54% higher risk of gastrointestinal bleeding with dabigatran. Rates of intracranial, other bleeding, and death were similar for dabigatran and warfarin.nnnCONCLUSIONSnDabigatran may increase the likelihood of gastrointestinal bleeds.

Venous Stenosis After Transvenous Lead Placement: A Study of Outcomes and Risk Factors in 212 Consecutive Patients

Background Venous stenosis is a common complication of transvenous lead implantation, but the risk factors for venous stenosis have not been well defined to date. This study was designed to evaluate the incidence of and risk factors for venous stenosis in a large consecutive cohort. Methods and Results A total of 212 consecutive patients (136 male, 76 female; mean age 69 years) with existing pacing or implantable cardioverter-defibrillator systems presented for generator replacement, lead revision, or device upgrade with a mean time since implantation of 6.2 years. Venograms were performed and percentage of stenosis was determined. Variables studied included age, sex, number of leads, lead diameter, implant duration, insulation material, side of implant, and anticoagulant use. Overall, 56 of 212 patients had total occlusion of the subclavian or innominate vein (26%). There was a significant association between the number of leads implanted and percentage of venous stenosis (P =0.012). Lead diameter, as an independent variable, was not a risk factor; however, greater sum of the lead diameters implanted was a predictor of subsequent venous stenosis (P =0.009). Multiple lead implant procedures may be associated with venous stenosis (P =0.057). No other variables approached statistical significance. Conclusions A significant association exists between venous stenosis and the number of implanted leads and also the sum of the lead diameters. When combined with multiple implant procedures, the incidence of venous stenosis is increased.

Trends in the pharmacologic management of atrial fibrillation: Data from the Veterans Affairs health system

BACKGROUNDnPrescribing rate control medications with or without antiarrhythmic drugs is often the first course treatment for atrial fibrillation (AF). Clinical trial data suggest that antiarrhythmic drugs are only marginally effective and have multiple drawbacks, whereas rate control alone is sufficient for most patients with minimally symptomatic AF. This study investigates changes in the use of oral rate and rhythm control therapy for AF during fiscal years 2002 through 2011 in the US Veterans Affairs (VA) health system.nnnMETHODSnPatients with new AF episodes were identified in Veterans Health Administration administrative data files, and receipt of oral rate- and rhythm-controlling drugs within 90 days of new AF episodes was determined for each patient.nnnRESULTSnThe percentage of patients receiving an oral rate-controlling medication decreased from 74.9% in 2002 through 2003 to 70.9% in 2010 through 2011. The use of digoxin decreased by >50%, whereas the use of β-blockers metoprolol and carvedilol increased. The proportion of patients receiving any oral antiarrhythmic medication decreased from 13.5% in 2002 through 2003 to 11.6% in 2010 through 2011, and use of the most frequently prescribed oral antiarrhythmic, amiodarone, decreased by 17%.nnnCONCLUSIONSnRate control remains the dominant strategy for treating new AF. The decrease in the use of oral antiarrhythmics may be due to lack of concrete data suggesting mortality and morbidity benefit as well as increasing use of the ablation approach.nnnBULLET POINTSnThe proportion of patients with new AF episodes who were prescribed oral rate or rhythm control medications decreased modestly from 2002 through 2011. The use of digoxin decreased by >50%, and amiodarone decreased by 17%. Rate control remains the dominant strategy for treating new AF.

Sex-Specific Comparative Effectiveness of Oral Anticoagulants in Elderly Patients With Newly Diagnosed Atrial Fibrillation

Background— Sex-specific comparative effectiveness of direct oral anticoagulants among patients with nonvalvular atrial fibrillation is not known. Via this retrospective cohort study, we assessed the sex-specific, comparative effectiveness of direct oral anticoagulants (rivaroxaban and dabigatran), compared to each other and to warfarin among patients with atrial fibrillation. Methods and Results— Elderly (aged ≥66 years) Medicare beneficiaries enrolled in Medicare Part D benefit plan from November 2011 to October 2013 with newly diagnosed atrial fibrillation formed the study cohort (65 734 [44.8%] men and 81 137 [55.2%] women). Primary outcomes of inpatient admissions for ischemic strokes and major bleeding were compared across the 3 drugs (rivaroxaban: 20 mg QD, dabigatran: 150 mg BID, or warfarin) using 3-way propensity-matched samples. In men, rivaroxaban use decreased stroke risk when compared with warfarin use (hazard ratio, 0.69; 95% confidence interval, 0.48–0.99; P=0.048) and dabigatran use (hazard ratio, 0.66; 95% confidence interval, 0.45–0.96; P=0.029) and was associated with a similar risk of any major bleeding when compared with warfarin and dabigatran. In women, although ischemic stroke risk was similar in the 3 anticoagulant groups, rivaroxaban use significantly increased the risk for any major bleeding when compared with warfarin (hazard ratio, 1.20; 95% confidence interval, 1.03–1.42; P=0.021) and dabigatran (hazard ratio, 1.27; 95% confidence interval, 1.09–1.48; P=0.011). Conclusions— The reduced risk of ischemic stroke in patients taking rivaroxaban, compared with dabigatran and warfarin, seems to be limited to men, whereas the higher risk of bleeding seems to be limited to women.

Long-Term Stability and Clinical Utility of Amplified Atrial Electrograms in a Single-Lead ICD System with Floating Atrial Electrodes.

Available atrial electrograms in implantable cardioverter defibrillators (ICDs) improve arrhythmia diagnosis, allow monitoring for atrial fibrillation, and may reduce the risk of inappropriate therapies. A recently introduced ICD system using a single‐lead with floating atrial electrodes provides diagnostic capability of a dual‐chamber system without placing an additional lead. Data on long‐term clinical performance of this system are limited.

Abnormal Epicardial Electrophysiologic Substrate in Patients with Early Repolarization Pattern and Reduced Left Ventricular Systolic Function: A Report of Two Cases

Introduction Early repolarization pattern (ERP) in the electrocardiogram (ECG) refers to ST-segment elevation above the isoelectric line in the absence of chest pain and/or to terminal QRS slurring or notching in 2 contiguous inferior and/or lateral leads. The underlying electrophysiologic mechanism of ERP remains elusive and is likely heterogeneous. The latter is supported by the fact that although ERP is commonly observed in the general population and has long been considered as a benign ECG finding, some recent data suggest its link (albeit weak) to increased risk of sudden cardiac death. In addition, different ECG markers of ERP may carry diverse prognostic significance while inferior J-point elevation of 2 mm appears to be the most strongly linked to arrhythmic death. Finally, the electrophysiologic mechanism of ERP may vary in patients with and without a structural heart disease. In this report, we describe electrophysiologic substrate in 2 patients with mild idiopathic left ventricle (LV) systolic dysfunction and terminal QRS notching (J-point elevation) in inferolateral leads.

Left Ventricular Dysfunction Caused by Unrecognized Surgical AV block in a Patient with a Manifest Right Free Wall Accessory Pathway

A 24-year-old male with Wolff-Parkinson-White syndrome developed systolic cardiomyopathy and severe heart failure following membranous ventricular septal defect repair and tricuspid valve replacement. Following successful catheter ablation of a right anterolateral accessory pathway (AP), complete AV block with junctional escape rhythm was noted. Patient subsequently underwent implantation of a biventricular ICD. Heart failure symptoms significantly improved soon after and left ventricular systolic function normalized 3 months post-procedure. In this case, surgically acquired AV block likely explains development of postoperative cardiomyopathy by facilitating ventricular activation solely via the AP and thereby increasing the degree of ventricular dyssynchrony.