Present treatment options for atrial fibrillation

Three-dimensional catheter tip force sensing using multi-core fiber Bragg gratings

Awareness of catheter tip interaction forces is a crucial aspect during cardiac ablation procedures. The most important contact forces are the ones that originate between the catheter tip and the beating cardiac tissue. Clinical studies have shown that effective ablation occurs when contact forces are in the proximity of 0.2 N. Lower contact forces lead to ineffective ablation, while higher contact forces may result in complications such as cardiac perforation. Accurate and high resolution force sensing is therefore indispensable in such critical situations. Accordingly, this work presents the development of a unique and novel catheter tip force sensor utilizing a multi-core fiber with inscribed fiber Bragg gratings. A customizable helical compression spring is designed to serve as the flexural component relaying external forces to the multi-core fiber. The limited number of components, simple construction, and compact nature of the sensor makes it an appealing solution towards clinical translation. An elaborated approach is proposed for the design and dimensioning of the necessary sensor components. The approach also presents a unique method to decouple longitudinal and lateral force measurements. A force sensor prototype and a dedicated calibration setup are developed to experimentally validate the theoretical performance. Results show that the proposed force sensor exhibits 7.4 mN longitudinal resolution, 0.8 mN lateral resolution, 0.72 mN mean longitudinal error, 0.96 mN mean lateral error, a high repeatability, and excellent decoupling between longitudinal and lateral forces.

Apixaban for reduction in stroke and other ThromboemboLic events in atrial fibrillation (ARISTOTLE) trial: design and rationale

Atrial fibrillation (AF) is associated with increased risk of stroke that can be attenuated with vitamin K antagonists (VKAs). Vitamin K antagonist use is limited, in part, by the high incidence of complications when patients' international normalized ratios (INRs) deviate from the target range. The primary objective of ARISTOTLE is to determine if the factor Xa inhibitor, apixaban, is noninferior to warfarin at reducing the combined endpoint of stroke (ischemic or hemorrhagic) and systemic embolism in patients with AF and at least 1 additional risk factor for stroke. We have randomized 18,206 patients from over 1,000 centers in 40 countries. Patients were randomly assigned in a 1:1 ratio to receive apixaban or warfarin using a double-blind, double-dummy design. International normalized ratios are monitored and warfarin (or placebo) is adjusted aiming for a target INR range of 2 to 3 using a blinded, encrypted point-of-care device. Minimum treatment is 12 months, and maximum expected exposure is 4 years. Time to accrual of at least 448 primary efficacy events will determine treatment duration. The key secondary objectives are to determine if apixaban is superior to warfarin for the combined endpoint of stroke (ischemic or hemorrhagic) and systemic embolism, and for all-cause death. These will be tested after the primary objective using a closed test procedure. The noninferiority boundary is 1.38; apixaban will be declared noninferior if the 95% CI excludes the possibility that the primary outcome rate with apixaban is >1.38 times higher than with warfarin. ARISTOTLE will determine whether apixaban is noninferior or superior to warfarin in preventing stroke and systemic embolism; whether apixaban has particular benefits in the warfarin-naïve population; whether it reduces the combined rate of stroke, systemic embolism, and death; and whether it impacts bleeding.

Antithrombotic therapy in atrial fibrillation: guidelines translated for the clinician

Atrial fibrillation (AF) is the most common cardiac arrhythmia in clinical practice, accounting for approximately one-third of hospitalizations for cardiac rhythm disturbances. The highest incidence of AF is in patients 70-80 years old and other high-risk populations. Although the diagnosis of AF is usually straightforward, effective treatment strategies are less well implemented. This is particularly true for antithrombotic therapy, which is very effective at preventing thromboembolic complications of AF. Stroke is the most significant morbidity in AF patients. The yearly risk of stroke increases from 1.5% for AF patients aged 50-59 to 23% for those aged 80-89. Ischemic strokes secondary to AF carry twice the risk of death when compared with strokes from other causes. We provide a practical and useful review of the most recent American College of Cardiology/American Heart Association/European Society of Cardiology guidelines-based care and future directions of antithrombotic therapy for patients with AF.

Stroke prevention in diabetic and other high cardiovascular risk patients

Diabetes is a major risk factor for stroke that is usually associated with risk factors such as hypertension, obesity, albuminuria, and dyslipidemia. Furthermore, atrial fibrillation and heart failure, two of the most important risk factors of stroke, are common in the diabetic population. With the rising epidemic of diabetes, the incidence of stroke is also on the rise. Implementations of effective stroke prevention strategies appear to be the most rational option to curb this growing epidemic. In this review, we examine the epidemiologic and the pathophysiologic association between stroke and diabetes, highlighting the population-based stroke preventive measures. These include hygienic and lifestyle changes, that if applied effectively could offer a great potential for stroke prevention and reduction of the cardiovascular burden in the diabetic populations.