New-onset left bundle branch block (NO-LBBB) isfrequent after aortic valve replacement (AVR) andis associated with a higher occurrence of high-grade atrioventricular block (AVB) at one year. Standard electrophysiologic study (sEPS) is suboptimal for predicting occurrence of AVB. The incremental value of ajmaline challenge (ajEPS) in addition to sEPS to detect, among patients with NO-LBBB after AVR, those at risk of AVB still remains unknown.

We identified all the consecutive patients with NO-LBBB after AVR in a single academic center from January 2016 to December 2018. EPS consisted in infra-hisian conduction assessment at baseline and after atrial pacing without AJ and, since January 2018, before and after ajmaline injection. EPS was positive if HV interval ³70ms at baseline or ³100ms after ajmaline and if intra/infra hisian block was reported at baseline of after AJ. Permanent pacemaker (PPI) was implanted if EPS was positive. Primary composite endpoint was occurrence of AVB (documented by ECG or PM control) or cardiac syncope during the follow-up.

We included 86 patients (79±10 years old), 63 transcatheter aortic valve implantation and 23 aortic bioprosthesis. sEPS was performed in 56/86 patients and this test was positive for 21/56. In ajEPS group (30/86 patients), the test was positive for 8/30. During the follow-up (11±7 months), in sEPS group, 6/35 patients, with negative test, reached the endpoint (3 with AVB and 3 with cardiac syncope) while there was no event after negative ajEPS. sEPS and ajEPS provided respectively a sensivity of 45% and 100%; a specificity of 64% and 81%; a positive predictive value of 24% and 37,5% and negative at 83% and 100%. ajEPS is more efficiency to predict endpoint occurrence (P-value 0.014 Fisher test) compared to sEPS (P-value 0,73 fisher test)

Our results are in favour the use of Ajmaline in addition to standard EPS to identify patients with NO-LBBB after AVR who need a PPI.