Substudy results stratified by the type of PVSFR. The prevalence of PVSFR is shown based on the type of PVSFR. Biphasic PVSFR was detected mostly in DMR and laminar PVSFR appeared in functional MR aetiologies. A-FMR, atrial functional mitral regurgitation; DMR, degenerative mitral regurgitation; PVSFR, pulmonary venous systolic flow reversal; V-FMR, ventricular functional mitral regurgitation.