Impact of implantation depth and cusp-specific calcium score on the incidence of left bundle branch block and infranodal conduction delay after transcatheter aortic valve replacement

Abstract

Abstract Background Conduction disorders and left bundle branch block (LBBB) after transcatheter aortic valve replacement (TAVR) are common. Risk factors, however, remain incompletely understood. Purpose To assess the impact of valve implantation depth and overall and cusp-specific aortic valve calcification on the incidence of LBBB and infranodal conduction delay post-TAVR. Methods In all patients undergoing TAVR between June 2020 and June 2021 the His-Ventricle (HV) interval was measured at least twice (pre-and post-valve deployment) and in the case of LBBB additionally one day after TAVR. Infranodal conduction delay was defined as HV > 55ms. The implantation depth of the valve was defined as the distance between the lower edge of the valve frame and the aortic annulus level and examined by two independent raters. Aortic valve calcification was assessed using the Agatston calcium score: overall and for each aortic cusp separately. Patients with valve-in-valve procedures were excluded. Results A total of 101 patients (mean age 81±5.7 years, 47% women) were included. The mean implantation depth was 5±3.1 mm. The median calcium score was 1840 AU [IQR 632-2400]. The baseline median HV interval was 46ms [IQR 39-50] and 8 patients demonstrated LBBB at baseline. Post-valve deployment LBBB was observed in 52 patients (52%), in whom the median HV interval was 52 ms [IQR 44-57]. Infranodal conduction delay was noted in 27 of 101 patients (27%). There was no correlation of delta HV (pre- vs. post-TAVR) and implantation depth or calcium score (r=0.08 and r=0.01, respectively). Patients with LBBB and infranodal conduction delay had comparable valve implantation depths (p=0.5) and total calcium scores (p=0.19) compared to patients with no LBBB and no infranodal conduction delay. Left ventricular outflow tract calcification measured at non-coronary cusp (NCC) level was a significant predictor for infranodal conduction delay post-valve deployment in a multivariable logistic regression model (OR 1.62, 95% CI 1.06-2.69 per 100 AU increase, p=0.04) and in a quantile regression model (p=0.002, Figure). In all models, the implantation depth was unable to predict new conduction disorders. Conclusion While the implantation depth had no impact on the incidence of LBBB or infranodal conduction delay, preprocedural assessment of aortic valve calcification for the NCC may help identify patients at risk for conduction disorders after TAVR. Further studies are needed to confirm these findings.