Introduction: Conduction system injury requiring permanent pacemaker implantation (PPM) becomes increasingly clinically relevant as transcatheter aortic valve replacement (TAVR) is employed in intermediate or low-risk patients (pts), given the potentially increased morbidity of PPM in pts with longer life expectancies and the low incidence of PPM implantation if pts are treated surgically. Therefore, identification of the pts at high-risk for PPM post TAVR may help guiding appropriate management strategies.
Hypothesis: Analysis of 3D reconstruction and tissue characteristics of the aortic valve apparatus may identify high-risk pts requiring PPM after TAVR.
Methods: CT images of 34 pts with TAVR were analyzed using 3D anatomical models of the aortic valve apparatus (segmentation) created by manually thresholding images from 320-800 HU for the separation of the aortic root from the atria and ventricles. 3D calcium volumes of the valve apparatus in the “conduction system zone” (Fig.) were quantified, where the conduction system enters the ventricular septum at the junction of right- and non-coronary cusps. The threshold of calcium volumes for stratification of PPM was 115 mm3 after the analysis of a ROC curve.
Results: 17 pts receiving PPM after TAVR were analyzed and compared to 17 pts without PPM. Average calcium volumes in the conduction system zone were three-fold higher in pts receiving PPM than in those without (190 ± 75 vs, 57± 38 mm3, p<0.05). Using calcium volumes of 115 mm3 at the conduction system zone as the cutoff value, the prediction accuracy for PPM after TAVR was 79% with sensitivity of 82% and specificity of 76%.
Conclusion: 3D reconstruction and tissue characterization of the aortic valve apparatus could identify the majority of the pts with severe aortic stenosis at high-risk for PPM after TAVR. With development of an automatic algorithm, this method may potentially become part of comprehensive risk evaluation prior to TAVR and reduce PPM burden and cost.