Overtreatment and undertreatment with anticoagulation in relation to cardioversion of atrial fibrillation (the RHYTHM-AF study).

Antithrombotic therapy is central to the management of atrial fibrillation. This analysis from the RHYTHM-atrial fibrillation (RHYTHM-AF) registry explored the appropriateness of antithrombotic therapy in relation to stroke risk and atrial fibrillation duration in patients with atrial fibrillation. RHYTHM-AF, a prospective multinational registry, enrolled consecutive adult patients with atrial fibrillation considered for cardioversion.

Comparison of the intrinsic vasorelaxant and inotropic effects of the antiarrhythmic agents vernakalant and flecainide in human isolated vascular and cardiac tissues.

This study explored the intrinsic vasorelaxant and inotropic effects of the mixed potassium and sodium channel blocker atrial antiarrhythmic vernakalant and the class IC antiarrhythmic agent flecainide in human isolated subcutaneous resistance artery and in ventricular trabecular muscle preparations. At test concentrations encompassing free plasma concentrations associated with clinical efficacy for conversion of atrial fibrillation, vernakalant (1-10 μM) displayed no significant direct effects on human resistance artery tone or ventricular contractility. In contrast, tested at equimolar concentrations, flecainide significantly reduced peak isometric contractile force (10 μM) and maximal rates of force development and decline (3 and 10 μM) in the human ventricular muscle preparation while displaying no significant effect on human resistance artery tone.

Mechanisms of embryonic coronary artery development.

Coronary artery development is a complex vasculogenic process that begins shortly after heart looping. Coronary vasculogenesis is regulated by the myocardium, but is spatially and temporally dependent on the epicardium and its precursor, the proepicardial organ, for the provision of coronary vascular progenitor cells. Better understanding of the mechanisms of coronary artery development may clarify mechanisms of disease and suggest new potential therapies for disorders of the coronary vasculature.