Chee W. Khoo

Acute Management of Atrial Fibrillation

Acute atrial fibrillation (AF) is the most common cardiac rhythm encountered in clinical practice and is commonly seen in acutely ill patients in critical care. In the latter setting, AF may have two main clinical sequelae: (1) haemodynamic instability and (2) thromboembolism. The approach to the management of AF can broadly be divided into a rate control strategy or a rhythm control strategy, and is largely driven by symptom assessment and functional status. A crucial part of AF management requires the appropriate use of thromboprophylaxis. In patients who are haemodynamically unstable with AF, urgent direct current cardioversion should be considered. Apart from electrical cardioversion, drugs are commonly used, and Class I (flecainide, propafenone) and Class III (amiodarone) antiarrhythmic drugs are more likely to revert AF to sinus rhythm. Beta blockers and rate limiting calcium blockers, as well as digoxin, are often used in controlling heart rate in patients with acute onset AF. The aim of this review article is to provide an overview of the management of AF in the critical care setting.

Novel oral anticoagulants

Oral anticoagulants have been used widely for the treatment of venous thromboembolism and stroke prevention. The vitamin K antagonists (VKAs), such as warfarin, have been around for the last 65 years and its efficacy as thromboprophylaxis remained largely unchallenged, at least until recently. Nonetheless, the VKAs have significant limitations with marked inter‐ and intra‐individual variability, requiring regular monitoring and have important food and drug interactions. Thus, there is an unmet need, with the quest for alternative oral anticoagulants with stable pharmacokinetics and pharmacodynamics that do not need monitoring. The novel oral anticoagulants are in 2 broad drug classes – the oral direct thrombin inhibitors and oral factor Xa inihibitors. This review article provides an overview of the pharmacology and describes the most recent published data on clinical trials with the new oral anticoagulants, which are in the more advanced stages of clinical development.

Clinical outcomes of acute stroke patients with atrial fibrillation.

Evaluation of: Kazumi K, Yasuyuki I, Kensaku S, Takeshi I, Shinji Y, Junya A. IV-tPA therapy in acute stroke patients with atrial fibrillation. J. Neurol. Sci. 276(1–2), 6–8 (2009). Stroke is the leading cause of disability and the second most common cause of death worldwide. The care and treatment of stroke patients have evolved over the last two decades, with increasing use of thrombolysis (e.g., intravenous tissue plasminogen activator in acute stroke patients), which has improved survival and recovery following stroke. The article under evaluation offers a greater insight into the relationship of clinical outcome of stroke and atrial fibrillation after tissue plasminogen activator infusion.

Burden of atrial fibrillation

ABSTRACT Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia seen in clinical practice and has attracted much attention due to its association with a substantial mortality and morbidity, particularly from stroke, thromboembolism and heart failure. This Editorial Commentary provides a brief overview of the clinical, economic and epidemiological burden of AF, particularly in the context of hospital readmission of patients with AF. It concludes that further studies on identifying factors and reasons for readmission in AF patients are therefore warranted. Understanding the patterns and factors that are responsible for readmission would help clinicians optimise the treatment strategies for AF patients and in turn improve quality of care and potentially lessen the large burden of AF on healthcare systems.

Insights from the dabigatran versus warfarin in patients with atrial fibrillation (RE-LY) trial

Oral anticoagulants such as warfarin have been used widely for the treatment of venous thromboembolism and stroke prevention in atrial fibrillation (AF) patients. Warfarin has significant limitations and also requires frequent monitoring. Thus, there is an unmet need, with the quest for alternative oral anticoagulants with stable pharmacokinetics and pharmacodynamics that do not need monitoring. The paper under evaluation provides us with up-to-date information on the safety and efficacy of a new oral anticoagulant, dabigatran, compared with warfarin for stroke prevention in AF patients.

Predictive value of atrial high-rate episodes for arterial stiffness and endothelial dysfunction in dual-chamber pacemaker patients

Various pacing studies have demonstrated an association between right ventricular pacing (RVp) and atrial fibrillation (AF), even after preserving atrioventricular (AV) synchrony. We aimed to assess the interaction between arterial stiffness, endothelial function and atrial high‐rate episodes (AHRE) in patients with dual‐chamber pacemakers.

The vitamin K antagonists and their limitations

The vitamin K antagonists (VKAs) have been the mainstay of oral anticoagulant therapy for more than 50 years, warfarin being the VKA most commonly used worldwide. The longstanding popularity of the VKAs is largely based on their effectiveness in the prevention and treatment of venous thromboembolism (VTE), as well as the prevention of systemic embolism in patients who have mechanical heart valves or atrial fibrillation (AF).

Atrial Fibrillation: Non Surgical Management

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice. The prevalence of AF increases with age. Indeed, there is one in four chance for both men and women aged 40 and above to develop AF during their life.1 With the increase in aging population, AF has become a major condition that requires extra resources in its management as well as the complications associated with it.

Common clinical indications for anticoagulation

As discussed in Chapter 1, an anticoagulant is a substance that possesses the properties to limit clot formation and therefore can be used therapeutically to prevent or treat thrombotic disorders. In this chapter we discuss the common clinical conditions in which anticoagulation should be considered and the evidence available to justify the use of an appropriate antithrombotic therapy in these clinical settings.

Dronedarone: NICE enough?

Atrial fibrillation (AF) is the most common sustained cardiac arrhythmia in clinical practice, and is associated with increased risk of morbidity and mortality. Studies indicate increasing prevalence of AF [1–5], in part linked to the aging population, and healthcare costs associated with this arrhythmia are projected to increase accordingly. Approximately 1% of the UK NHS costs can be attributed to AF, an economic burden similarly reported in other developed countries [6–8]. Despite the emergence of catheter ablation of AF, pharmacological treatment remains central to the management of AF. The strategy of pharmacological rhythm control, although intuitively attractive, is hampered by limited efficacy and significant toxicity associated with anti arrhythmic agents. Class I antiarrhythmic agents have been shown to increase mortality in patients with structural heart disease. Similarly, class III agents can result in repolarization abnormalities and increased risk of ventricular arrhythmias. Although the risk of proarrhythmia appears to be lower with amiodarone, the risk of thyroid dysfunction and potentially fatal hepatic and pulmonary toxicity restricts its long-term use [9]. Indeed, the failure of antiarrhythmic drugs to safely and effectively maintain sinus rhythm in the long term, and overenthusiastic discontinuation of anticoagulation therapy, are widely acknowledged as the reasons for the failure of pharmacological rhythm control to outperform rate control in randomized trials of patients with AF [10,11]. Buoyed by indications of better survival in patients in whom maintenance of sinus rhythm is successful [12], investigators have continued the search for safer and more effective strategies for rhythm control. As ongoing clinical trials evaluate the precise role of catheter ablation of AF, a new antiarrhythmic drug, dronedarone, has recently emerged as a promising antiarrhythmic agent for rhythm control, which also reduces hospitalizations in high-risk patients with AF.