Conduction disturbances and permanent cardiac pacing after transcatheter implantation of the CoreValve aortic bioprosthesis: initial single centre experience.

BACKGROUND: The rate of significant conduction disturbances requiring permanent pacemaker implantation (PPI) following surgical aortic valve replacement (AVR) is 2-8%. Transcatheter aortic valve implantation (TAVI) is an alternative management approach in patients with severe aortic stenosis who are not considered candidates for AVR. The TAVI using the CoreValve (CV) bioprosthesis is associated with a nearly 30% rate of conduction disturbances requiring postprocedural PPI.

AIM: To provide an initial evaluation of the rate of conduction disturbances and the need for PPI, and to analyse factors that increase the risk of this complication in patients undergoing TAVI using CV bioprosthesis. In addition, we evaluated the rate of permanent conduction disturbances in patients who underwent PPI at one year after TAVI.

METHODS: We studies 22 initial patients in a single centre who underwent CV bioprosthesis implantation in 2009-2010. After exclusion of 6 patients with preprocedural PPI, we ultimately evaluated 16 patients. Uni- and multivariate analyses were performed using χ(2), Fisher, and Wilcoxon tests, and logistic regression analysis was performed using the SAS software.

RESULTS: Overall, 8 (50%) patients in our study group required PPI after TAVI (TAVI + PPI), and the remaining 8 patients did not require PPI (TAVI). The most common indication for PPI was complete heart block. The decision to implant a pacemaker was made on average at 9 ± 7 days following TAVI (range 3 to 22 days). When we analysed risk factors for PPI that were unrelated to the TAVI procedure, we found that the TAVI + PPI group was characterised (vs the TAVI group) by a significantly larger diameter of the native aortic valve (p = 0.03) and a larger left ventricular outflow tract (LVOT) dimension in the frontal (p = 0.02) and the corresponding frontal dimension in the transverse view (p = 0.01) by computed tomography angiography. Logistic regression analysis showed that the risk of PPI increased more than 2.5 times for each increase in the aortic annulus diameter by 1 mm (OR 2.64; 95% CI 0.90-7.74). None of the risk factors related to TAVI resulted in a significant increase in the rate of PPI. Among the patients who underwent PPI, we only noted a trend for a larger valvulotomy balloon diameter (p = 0.08), shorter procedure duration (p = 0.06), and deeper CV insertion within LVOT (p = 0.09). In addition, the bioprosthesis was inserted deeper in those patients who developed new LBBB after TAVI (p = 0.06). The ECG analysis at one day after the procedure showed a significant prolongation of PR, QRS, QT, and QTc intervals, and increased left axis deviation in the TAVI + + PPI group. In addition, the TAVI + PPI group showed increased QRS duration (p = 0.03) and increased left axis deviation (p = 0.049) compared to the TAVI group. Each increase in QRS duration by 10 ms was associated with 2.5-fold increase in the risk of PPI (OR 1.10; 95% CI 0.97-1.22), and each increase in PR interval duration by 10 ms with a 23% increase in risk (OR 1.02; 95% CI 0.99-1.05). New LBBB following CV implantation was noted significantly more frequently in the TAVI + PPI group vs the TAVI group (p 〈 0.0003). Pacemaker interrogation at one year after TAVI showed that the mean percentage of ventricular pacing in all patients with a pacemaker (DDD and VVI) pacing was 41%, and it was less than 10% in 2 patients.

CONCLUSIONS: 1. Transcatheter implantation of a CV bioprosthesis is associated with an increased risk of persistent conduction disturbances and subsequent PPI. 2. New LBBB after TAVI may predict the need for PPI. 3. Careful ECG monitoring is necessary for one week after CV bioprosthesis implantation due to a risk of atrioventricular conduction disturbances and the need for PPI. 4. Patients at an increased risk of postprocedural PPI may be those with deep bioprosthesis insertion in LVOT, larger LVOT diameter, and larger aortic annulus diameter in the frontal view. These observations require confirmation in a larger group of patients.