4D flow CMR detects progressive improvement in ventricular function following cardioversion of atrial fibrillation

Background Atrial fibrillation (AF) causes impairment of cardiac hemodynamics and substantial cardiovascular morbidity. While AF is difficult to assess with cardiac gated CMR, successful electrical cardioversion of chronic AF is often followed by a transient period of atrial stunning where absence of mechanical atrial contraction, similar to that seen in AF, persists despite reinstitution of sinus rhythm. 4D flow CMR enables assessment of ventricular function according to the volume and kinetic energy of different LV flow components. The volume and end-diastolic kinetic energy (KE) of LV inflow passing directly to ensuing outflow (Direct flow) reflect aspects of left atrial-ventricular coupling and have been proven to be markers of LV dysfunction in failing hearts. In this study we hypothesize that left atrial (LA) stunning will contribute to impaired LV function reflected by reduced volume and end-diastolic KE of the LV Direct flow component.