Predictors of new conduction disturbance in the BAV cohort
The current study revealed that the implantation depth – MS length and severe LVOT calcification were independent predictors of new CD following TAVR for BAV with SAPIEN 3. The findings on implantation depth and MS length were consistent with prior studies concerning BAV regardless of the THVs (24 ) and with TAV with self-expandable THV (18 ). In addition, the high implantation technique with balloon-expandable SAPIEN 3 THV achieved lower rate of new conduction disturbances. Furthermore, high implantation was considered safe and provided good hemodynamic results (16 ). Our study implicates the advantage of high implantation for BAV in terms of reducing CD. The comparison between deeper implantation depth (implantation depth < MS) and higher implantation depth (implantation depth ≥ MS) showed a similar complication rate other than CD and similar hemodynamic outcomes.
The impact of LVOT calcification on new CD has been controversial. Although some studies did not find association with LVOT calcification and an increased risk of PPI (28, 29 ), the location of LVOT calcification has been reported as a predictor of PPI in the other studies (19, 30 ). LVOT calcification below NCC (19 ), LCC (30 ), and RCC (30 ) were individually reported as the predictor of new PPI. Our analysis revealed the overall LVOT calcification, regardless of the location, as a predictor of new CD, however, the distribution of calcification was not assessed.
Careful THV sizing and implantation strategy is implicated for the TAVR for BAV anatomy with severe LVOT calcification. The LVOT calcification may increase mechanical stress to the LVOT tissue and conduction system (19, 30 ). In theory, this problem might be solved with the high implantation technique because high-implanted THV would have less chance to interact with the conduction system nor the LVOT calcification.