Using 5D flow MRI to decode the effects of rhythm on left atrial 3D flow dynamics in patients with atrial fibrillation

Purpose This study used a 5D flow framework to explore the influence of arrhythmia on thrombogenic hemodynamic parameters in patients with atrial fibrillation (AF). Methods A fully self‐gated, 3D radial, highly accelerated free‐running 5D flow sequence with interleaved four‐point velocity‐encoding was acquired using an in vitro arrhythmic flow phantom and in 25 patients with a history of AF (68 ± 8 y, 6 female). Self‐gating signals were used to calculate AF burden, bin data, and tag each k‐space line with its RRLength. Data were binned as an RR‐resolved dataset with four RR‐interval bins (RR1‐RR4, short‐to‐long) for compressed sensing reconstruction. AF burden was calculated as interquartile range of all intrascan RR‐intervals divided by median RR‐interval, and left atrial (LA) stasis as the percent of the cardiac cycle where the velocity was