Is There a Role for Vitamin K Antagonist in the Management of Atrial Fibrillation in 2023?

PURPOSE OF REVIEW: To address the following question: Are vitamin K antagonists (VKA) obsolete as stroke prevention therapy for patients with atrial fibrillation (AF) and thromboembolic risk factors? RECENT FINDINGS: A patient-level meta-analysis of the pivotal phase III randomized trials confirmed the favorable treatment effect of direct oral anticoagulants (DOAC) over VKA in multiple key patient subgroups. Among patients with AF and rheumatic heart disease (85% of whom had mitral stenosis), a randomized trial showed that rivaroxaban was not superior to VKA for stroke prevention. Caution should be exercised when prescribing DOAC for AF-related stroke prevention for patients with elevated body mass indices or history of bariatric surgery, patients with bioprosthetic heart valves, and those who require treatment with drugs that interact with cytochrome P450 and P-glycoprotein. Drug costs associated with DOAC remain considerably higher than VKA, by up to 30-fold. Direct oral anticoagulants are preferable over VKA in the large majority of eligible patients with AF and thromboembolic risk factors. The use of DOAC should be avoided for patients with mechanical heart valves or moderate/severe rheumatic mitral stenosis. Vitamin K antagonist is a reasonable option for patients who are under-represented in randomized trials, when there are significant drug-drug interactions or when patients cannot afford DOAC agents due to their higher costs.

The Prevalence of Low Left Atrial Appendage Emptying Velocity and Thrombus in Patients Undergoing Catheter Ablation for Atrial Fibrillation on Uninterrupted Peri-procedural Warfarin Therapy.

Introduction: The 2012 HRS/EHRA/ECAS guidelines encourage pre-procedural transesophageal echocardiography (TEE) prior to ablation for atrial fibrillation (AF), but acknowledge a lack of consensus in patients maintained on therapeutic warfarin before, during and after the procedure. This is partly because the incidence of left atrial appendage (LAA) thrombus is so low, that it is hard to draw clear conclusion regarding the characteristics of patients who develop thrombus. We hypothesize that the presence of low LAA emptying velocities, which predisposes to thrombus, and/or thrombus itself can be predicted in patients undergoing ablation, based upon clinical characteristics and transthoracic echocardiography (TTE). Methods: In this multicentre study, we undertook TTE and transesophageal echocardiograms (TEE) in 586 patients (age 59.9±0.4 years old, 64.5% male) undergoing catheter ablation for AF who were anticoagulated on warfarin (target international normalized ratio 2-3.5) for ≥3 consecutive weeks prior to procedure and maintained on warfarin for the procedure. Results: Low peak LAA emptying velocities (<40cm/s) were identified in 111 (24.7%) patients and LAA thrombus was identified in 3 patients (0.5%) despite having therapeutic INRs. The 3 patients with thrombus had LAA emptying velocities of 23, 29 and 31 cm/s. None of the remaining patients had a peri-procedural stroke. Patients with peak LAA emptying velocities <40cm/s or thrombus on TEE had significantly (p<0.05) higher CHA2DS2-VASc scores (1.7± 0.1 v's 1.4±0.1), and were more likely to have impaired LVSF (odds ratio [95% CI]: 2.66 [1.52-4.66]), a LA diameter >4.6cm on TTE (2.40 [2.13-5.41]), or persistent AF (2.60 [1.63-4.14]) compared to those with a higher LAA velocity without thrombus. Conclusion: In patients on uninterrupted warfarin therapy, a CHA2DS2-VASc score ≥1 or LA diameter >4.6cm on TTE identifies 91.5% of those at risk of developing thrombus with LAA emptying velocity of <40 cm/s and 100% of those with thrombus in our cohort.

Increased energy intake entirely accounts for increase in body weight in women but not in men in the UK between 1986 and 2000.

There is debate over the casual factors for the rise in body weight in the UK. The present study investigates whether increases between 1986 and 2000 for men and women were a result of increases in mean total energy intake, decreases in mean physical activity levels or both. Estimates of mean total energy intake in 1986 and 2000 were derived from food availability data adjusted for wastage. Estimates of mean body weight for adults aged 19-64 years were derived from nationally representative dietary surveys conducted in 1986-7 and 2000-1. Predicted body weight in 1986 and 2000 was calculated using an equation relating body weight to total energy intake and sex. Differences in predicted mean body weight and actual mean body weight between the two time points were compared. Monte Carlo simulation methods were used to assess the stability of the estimates. The predicted increase in mean body weight due to changes in total energy intake between 1986 and 2000 was 4·7 (95 % credible interval 4·2, 5·3) kg for men and 6·4 (95 % credible interval 5·9, 7·1) kg for women. Actual mean body weight increased by 7·7 kg for men and 5·4 kg for women between the two time points. We conclude that increases in mean total energy intake are sufficient to explain the increase in mean body weight for women between 1986 and 2000, but for men, the increase in mean body weight is likely to be due to a combination of increased total energy intake and reduced physical activity levels.