Importance of Size and Circumferential Shape of the Aortic Annulus Assesed with Computed Tomography to Determine Post-Tavi Aortic Regurgitation

Aims: Aortic regurgitation (AR) after TAVI has been related to higher mortality. Several predictors of AR, some of them based on multislice computed tomography (MSCT), have been described to the date, but little is known on how the aortic annulus (AA) shape may affect the valve expansion leading to AR. Methods: TAVI was implanted in 88 pts in our institution between april/2009 and december/2012. We included 66 of them who underwent MSCT before the procedure. Calcium degree of aortic valve was classified in low, moderate or severe by an expert in cardiac imaging. Major, minor and mean AA were estimated, and its area was automatically determined. The ratio major/minor AA diameters was calculated as an index of circumferencial shape (more circumferential as closer to 1). Results: Mean age was 81±6 yrs, 37.9% were females. Mean STS-score was 6.8±4.8% and logisticEuroSCORE 16.7±9.4%. Mean ejection fraction was 54.9±14.1% and a 7.5% presented 3 to 4 degrees AR at baseline. The valve was considered severely calcified in 56.1%. Four pts required a second valve implantation and 20 pts (30.3%) post-dilation leading to a final mild degree of AR in 35 pts (53.0%), moderate in 25 pts (37.8%), and severe in 2 pts (3.0%). The procedure was successful in the 97% and 3 deaths (4.5%) occurred during the in-hospital stay. Significant differences were found between AA diameter as measured by echo (23.8±2.7 mm) and MSCT (24.6±2.9 mm), p<0.001. The main predictors related to post-TAVI AR≥2 were a lower baseline LVEF with 55% (IQR: 35-64) vs. 62% (IQR: 47-67), p=0.020, and several parametres from MSCT: Maximum AA diameter of 28.0±5.6 vs. 26.1±4.2 mm, p=0.012; median AA area of 813 (IQR: 715-890) mm vs. 648 (IQR: 570-719), p<0.001; and a mean index of circumferential shape of 0.76±0.13 vs. 0.83±0.11, p=0.031. Also, when severely calcification of the valve occurred AR≥2 was more frequent (74% vs. 26%, p=0.033). The ROC curve analysis determined 28.5 mm as the best cut-off value of maximum diameter to determine worse AR (S=74.0%, Sp=58.0%, 95% CI[0.544-0.846], p=0.009) and 734 mm2 for AA area (S=78%, Sp=77%, 95% CI[0.648-0.911], p<0.001). In the multivariant model, AA area was the only independent predictor of post-TAVI AR≥2 with an OR=1.008 for each mm2 of increase, 95% CI (1.003-1.012), p=0.001. Conclusions: Post-TAVI AR can be predicted by several parametres of MSCT including severe calcification of the valve, but also AA morphology as determined by the index of circumferential shape and its area.