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Electrophysiology

Improved Atrial Fibrillation Outcomes Despite Rising Arrhythmia Prevalence

7 Jul, 15 | by Alistair Lindsay

Little is known about temporal trends in atrial fibrillation (AF) incidence, prevalence, and outcomes. Using the Framingham Heart Study, Schnabel and colleagues assessed AF incidence, prevalence, and outcomes over 50 years (202,417 person-years). Researchers drew on a cohort of 9,511 participants enrolled between 1958 and 2007 in which 1,544 incident AF cases (47% women) were identified. Over the study period, age-adjusted incidence increased threefold (3.7 to 13.4 new cases per 1000 person-years in men and from 2.5 to 8.6 new cases per 1000 person-years in women) and age-adjusted prevalence increased fourfold (20.4 to 96.2 cases per 1000 person-years in men and from 13.7 to 49.4 cases per 1000 person-years in women). more…

Does Defibrillation Threshold Testing Confer Benefit to ICD Recipients?

1 Apr, 15 | by Alistair Lindsay

Defibrillation threshold (DFT) testing to confirm an implantable cardioverter-defibrillator (ICD) could effectively terminate ventricular fibrillation is widely accepted as part of routine practice without much evidence of efficacy. However, advances in ICD technology and evidence of initial shock efficacy have called into question the importance of DFT testing. While testing rarely results in immediate complications, ICD shocks can have adverse long-term consequences and DFT requires sedation that adds costs and complexity to the procedure. Healey and colleagues explored the efficacy and safety of ICD implantation with and without DFT testing in the single blind, multicenter, randomized non-inferiority Shockless IMPLant Evaluation (SIMPLE) trial. ICD candidates (including secondary prevention and cardiac resynchronization recipients) were randomized to each arm (1247 without DFT and 1253 receiving standard therapy). more…

The SAFETY Clinical Trial: Intensive Outpatient Follow-up to Improve Outcomes after Hospitalization for Atrial Fibrillation

1 Feb, 15 | by Alistair Lindsay

The prevalence of atrial fibrillation (AF) is increasing with a concurrent rise in the number of hospitalizations for AF. The standard versus atrial fibrillation-specific management strategy (SAFETY) trial sought to test a nurse-led intervention following hospital discharge for chronic, non-valvular AF on patient outcomes of unplanned admission or all-cause death. Participants in the intervention arm received Holter monitoring and a home visit from a cardiac nurse within one to two weeks after discharge to tailor management of AF and comorbid disorders. After a median of 905 days of follow-up, 127 (76%) patients receiving the SAFETY intervention reached the primary endpoint compared to 137 (82%) patients receiving standard management (hazard ratio 0.97, 95% CI 0.76–1.23; p=0.85). more…

Left atrial appendage closure in atrial fibrillation – is a comparison against warfarin still meaningful?  

20 Dec, 14 | by Alistair Lindsay

The majority of patients with nonvalvular atrial fibrillation (AF) have an indication for anti-coagulation to reduce the risk of stroke. As the left atrial appendage (LAA) is thought to the be the predominant source of thromboembolic events in the setting of AF, LAA closure may provide an alternative to anti-coagulation for stroke risk reduction without the associated bleeding concerns of anti-coagulation. This multi-center, randomized, unblinded trial compared LAA closure to warfarin in patients with AF and at least one other stroke risk factor (i.e. CHADS2 scores ≥ 1).   Patients were followed for four years and the primary outcome was a composite of stroke, systemic embolism, and cardiovascular/unexplained death. In the intention to treat analysis for efficacy the LAA closure groups had 2.3 events per 100 patient-years compared to 3.8 events per 100 patient-years in the warfarin group (relative risk 0.60 favoring device; 95% credible interval, 0.41-1.05). The most frequent adverse event with the device was serious pericardial effusion and survival curves demonstrated an earlier risk of adverse events in the device group. more…

Cryptogenic stroke due to undetected atrial fibrillation – longer ECG monitoring may be the key

23 Jul, 14 | by Alistair Lindsay

Up to 40% of ischemic strokes remain unexplained after routine evaluation and thus are considered cryptogenic. However, a number of these strokes may be due to an undetected episode of paroxysmal atrial fibrillation (AF) where anticoagulation can reduce the risk of subsequent ischemic stokes. Although a minimum of 24 hours of ECG monitoring is guideline recommended in the evaluation of ischemic stroke to identify AF, the optimal duration of monitoring remains undetermined. Among patients with cryptogenic stroke, two concurrent publications evaluated the AF diagnostic yield of extended ECG monitoring. more…

Cardiac resynchronization therapy benefit holds up in clinical practice

8 Jun, 14 | by Alistair Lindsay

The benefit of cardiac resynchronization therapy with a defibrillator (CRT-D) relative to implantable cardioverter-defibrillator (ICD) therapy alone has not been evaluated in routine clinical practice.  This study used data from the National Cardiovascular Data Registry’s ICD Registry linked with Medicare claims data to compare outcomes after CRT-D and ICD implantation in community practice.  The analysis included 7090 propensity matched patients who underwent either CRT-D or ICD implantation between 2006 and 2009 at one of 780 U.S. hospitals participating in the NCDR ICD registry.  Patients were over age 65 and met criteria for CRT-D implantation (left ventricular ejection fraction ≤ 35% and QRS duration ≥ 120ms). Over 3 years of follow-up, CRT-D was associated with lower risk of mortality (HR 0.82, 99% CI 0.73-0.93), all-cause readmission (HR 0.86, 99% CI 0.81-0.93), and heart failure readmission (HR 0.78, 99% CI 0.69-0.88) compared with ICD therapy.  However, CRT-D was also associated with a higher risk of device related infection (HR 1.90, 99% CI 1.07–3.37).  In subgroup analyses, the reduced risk of heart failure readmission was most prominent among patients with left bundle branch block or QRS duration of at least 150 ms. more…

Warfarin for atrial fibrillation in patients with chronic kidney disease – does the thromboembolic benefit outweigh the bleeding risk?

8 Jun, 14 | by Alistair Lindsay

Chronic kidney disease (CKD) predisposes to high risks for both thrombo-embolism and bleeding. As a result, understanding the risk-benefit profile for use of anticoagulation therapies among CKD patients with atrial fibrillation is important to optimize patient outcomes. However, clinical trials evaluating efficacy and safety of anti-coagulants for atrial fibrillation generally exclude CKD patients and observational studies have had conflicting results. Accordingly, this prospective cohort study of 24,317 atrial fibrillation patients admitted with myocardial infarction in Sweden examined the association between warfarin therapy and patient outcomes by stage of CKD. Warfarin was prescribed in 21.8% patients and CKD (estimated glomerular filtration rate [eGFR] < 60 mL/min/1.73m2) was present in 51.7%. Compared with patients not treated with warfarin, the risk-adjusted composite outcome of death, myocardial infarction, or ischemic stroke was lower at 1 year of follow-up among patients treated with warfarin, regardless of CKD class. This reduction in thromboembolic events was not offset by an increased risk of bleeding events. more…

Weight reduction results in atrial fibrillation symptom improvement

2 Feb, 14 | by Alistair Lindsay

Obesity is known risk factor for atrial fibrillation (AF). However, the effect of weight reduction on AF symptom burden is unknown. In this study, 150 patients with symptomatic AF who were overweight or obese were randomized to a physician led weight loss program (intervention arm) or self-directed general lifestyle measures (control arm). All patients received intensive cardiometabolic risk factor management and were evaluated at 3 monthly intervals by blinded study personnel. Primary outcomes of interest were AF symptom burden and symptom severity evaluated using a validated tool to assess disease specific patient-reported health status. Secondary outcomes included holter-derived episodes of AF, left ventricular thickness and left atrial size on echocardiograms. more…

Biventricular pacing for bradycardia

15 Jul, 13 | by Alistair Lindsay

Right ventricular (RV) pacing is used in patients presenting with high degree atrioventricular block, both to relieve symptoms related to bradycardia and improve prognosis. The majority of these patients are elderly and many of them will have a degree of co-existing left ventricular dysfunction which may be exacerbated by the electrical and mechanical dyssynchrony that occurs with RV pacing. The large cardiac-resynchronization (CRT) pacing studies performed to date have systematically excluded patients with indications for standard bradycardia pacing devices so as to concentrate solely on the benefits derived from cardiac resynchronisation, and consequently there is a paucity of data regarding this group. more…

Does warfarin need to be stopped for device insertion?

12 Jun, 13 | by Alistair Lindsay

Over 1.6 million pacing or cardioverter defibrillator (ICD) devices are implanted worldwide annually and up to 1/3 of this cohort have an indication for long-term anticoagulation therapy. Current guidelines suggest discontinuing the oral anticoagulant and initiating bridging therapy with heparin but this strategy is associated with increased costs, a short but high risk period of normal coagulability, and of itself is associated with a pocket haematoma rate of between 20 to 30%. Small case series have suggested that it may be safe to perform surgery without interrupting warfarin treatment but thus far no adequately powered prospective trial has reported on this strategy. more…

Highlighted articles from non-cardiological journals relevant to cardiology.

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