UNLABELLED This study investigates the natural course of paravalvular regurgitation (PAR) with serial transesophageal echocardiography (TEE) measurements. METHODS TEE studies were performed at 30 days and 1 year post TAVI with the self-expanding CoreValve for the treatment of severe aortic valve stenosis in 50 patients. In addition to conventional measurements, PAR perimeter and orifice area were assessed in the cross-sectional short-axis view at the level of the native aortic annulus. RESULTS At 30 days, PAR was classified as none in 26 patients (52%), mild in 19 patients (38%) and moderate in 5 patients (10%). Between 30 days and 1 year, the number and size of PAR jets decreased and PAR was absent in 30 patients (60%) (P=.58 compared with 30-day results). Paravalvular regurgitation perimeter decreased from 8.2 ± 10.9% to 4.7 ± 7.7% (P<.01), a relative reduction of 43%. Cross-sectional area of regurgitation decreased from 0.22 ± 0.36 cm² to 0.12 ± 0.20 cm² (P=.01), a relative reduction of 45%. This improvement was observed in patients with mild and moderate PAR. No patient without PAR at 30 days developed PAR at 1-year follow-up. CONCLUSIONS PAR perimeter and area as visualized by Color-Doppler TEE in the cross-sectional view decreased by about 45% between 30 days and 1 year post implantation of the self-expanding CoreValve.