The Canadian journal of cardiology
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Warfarin is effective for the prevention and treatment of thromboembolism but produces variable anticoagulant effects and requires routine monitoring of the international normalized ratio (INR) to optimize the balance between efficacy and safety. The new oral anticoagulants (NOACs) have a more predictable anticoagulant effect and were recently demonstrated to be at least as efficacious and safe as warfarin despite being administered in fixed doses without routine coagulation monitoring. Specific laboratory tests have been developed to measure the anticoagulant effect of the NOACs but are not yet widely available, and the relation between drug levels and both coagulation test results and outcomes is uncertain. ⋯ In patients with major or life-threatening bleeding and those requiring surgery, the anticoagulant effects of warfarin can be reversed using oral or intravenous vitamin K, fresh frozen plasma (FFP), and prothrombin complex concentrates (PCCs). Specific antidotes are under development for the NOACs but are not yet approved for clinical use. PCCs and recombinant factor VIIa may improve hemostasis in patients in whom bleeding develops during treatment with a NOAC, but their efficacy is unproven.
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Randomized controlled trials have demonstrated benefits from antithrombotic therapies for coronary artery disease (primary prevention, stable coronary artery disease, acute coronary syndromes, and percutaneous intervention) and for atrial fibrillation. The regimens with the optimal balance of efficacy and safety with coronary artery disease depend on the particular clinical manifestation, with atrial fibrillation on the risk of stroke, and with both conditions on the competing risk of major bleeding with the chosen antithrombotic therapy. ⋯ Practice guidelines now recommend oral anticoagulant therapy for most patients with atrial fibrillation and consideration of "triple therapy" (oral anticoagulant and aspirin and clopidogrel) when there is a concomitant acute coronary syndrome or stent placement, though acknowledging the risks of major bleeding. In the absence of definitive trials of combination therapies, such practice guidelines are based on extrapolations from randomized trials and observational data.
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A growing number of patients with atrial fibrillation are treated with oral anticoagulation (OAC), and a large proportion of them will require surgical or other invasive procedures. These procedures typically involve interruption of OAC with or without the use of heparin bridging; however; there has been a dramatic change in this practice during the past 3 years. The introduction of short-acting, new oral anticoagulants and the growing popularity of some low-risk procedures with continued OAC have transformed our practice. Physicians and surgeons who treat patients with atrial fibrillation must be aware of these changes and understand how to deal with the new challenges they may encounter.
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The term "silent" atrial fibrillation (AF) has recently re-emerged to describe atrial arrhythmias that are detected by implanted cardiac devices but would generally go undetected in the clinical setting. The precise role that silent AF plays in increasing the risk of ischemic stroke is not fully understood. The purpose of this article is to: (1) review the current evidence demonstrating that silent AF is associated with thromboembolic events; (2) describe the temporal proximity of silent AF episodes to thromboembolic events; (3) present data on the incidence of newly detected silent AF in patients without a previous history of AF; and (4) provide an overview of ongoing and new clinical studies on this important topic. ⋯ The AF burden threshold which confers this increased thromboembolism risk is not precisely defined, but might be as brief as several minutes to several hours. The advent of novel oral anticoagulation medications, which offer the promise of improved efficacy along with superior safety profiles, might warrant more aggressive identification of patients who might benefit from these therapies. However, to find high risk patients who have brief episodes of silent AF will likely require new methods of monitoring to permit the detection of this elusive but potentially dangerous arrhythmia.
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Multicenter Study Comparative Study
Does preoperative atrial fibrillation portend a poorer prognosis in patients undergoing isolated aortic valve replacement? A multicentre Australian study.
Preoperative atrial fibrillation (preop-AF) has been associated with poorer early and late outcomes after cardiac surgery. Few studies, however, have evaluated the impact of preop-AF on early and late outcomes after isolated aortic valve replacement (AVR). ⋯ Preop-AF is associated with an increased risk of late mortality after isolated AVR. As such, concomitant atrial ablation with AVR should be prospectively studied.