Membranous septum area and the risk of conduction abnormalities following transcatheter aortic valve implantation

Background

Conduction abnormalities (CA) after TAVI remain problematic. Membranous septum (MS) depth correlates inversely with new CA though within-patient variability exists.

Objectives

To determine the association of CT-derived MS area with new CA after TAVI.

Methods

MS depth was measured along its width (20 ​% intervals) to calculate MS area in 140 patients without CA. The primary outcome was PPI or new persistent LBBB at discharge.

Results

New CA occurred in 49 (35 ​%) patients of whom 10 (7.1 ​%) required PPI and 39 (27.9 ​%) developed persisting LBBB. MS area was significantly smaller in those with new CA (20.1 [8.6] vs. 41.2 [18.0] mm2; p ​< ​0.01). By multivariable regression, a model including MS area and TAVI contact (MS width∗implant depth): MS area ratio showed better discrimination for new CA compared with a model including MS depth and MS depth – implant depth (AUC 0.89 [95 ​% CI 0.83–0.94] vs. 0.84 [95 ​% CI 0.76–0.90]; p ​= ​0.05, respectively). Optimal cut off point for correct classification of new CA for MS depth was 3.9 ​mm (sensitivity 73 ​%, specificity 76 ​%, PPV 58 ​% and NPV 84 ​%), 28.0 ​mm² for MS area (sensitivity 88 ​%, specificity 78 ​%, PPV 68 ​% and NPV 92 ​%) and 1.88 (sensitivity 63 ​%, specificity 81, PPV 77 ​% and NPV 68 ​%) for TAVI contact: MS area ratio. To minimize new CA, maximal valve implant depth should ≤ (1.88 ∗ MS area)/MS width.

Conclusions

Pre-procedural assessment of the MS area offers additional predictive value for development of new conduction abnormalities after TAVI when compared with MS depth and can guide implant depth.