Extrapolating echocardiographic determinants of elevated Left Atrial Pressure (LAP) to Cardiac Magnetic Resonance Imaging (CMR) to determine the best CMR correlate of elevated LAP

Background The ratio of the transmitral early inflow wave velocity (E wave velocity) and the velocity of the septal (or lateral) mitral annulus as measured by tissue Doppler (the e’ wave velocity) can be used to estimate left atrial pressure on echocardiographic examination. An elevated E/e’ (more than 15 when using the septal mitral annular velocity) is an established measure of elevated LAP. Furthermore when the left atrial pressure rises, simultaneous changes take place in the pulmonary venous flow. The normal flow pattern in the pulmonary veins consist of a prominent systolic and a smaller diastolic component with the ratio of the peak systolic to diastolic velocities more than 1. With elevated left atrial pressure the ratio drops to below 1.