Po-05-019 when right is wrong: incidence and outcomes of right bundle branch block following transcatheter aortic valve replacement

Right bundle branch block (RBBB) following transcatheter aortic valve replacement (TAVR) for aortic stenosis is uncommon. However, its incidence and prognosis have not been well-described. To characterize the incidence of post-TAVR RBBB alongside its associated risk of permanent pacemaker (PPM) implantation and mortality. All patients ≥18 years who underwent TAVR at the Mayo Clinic Enterprise from June 2010 to May 2021 were considered; patients with pre-TAVR RBBB and/or PPM were excluded from the analysis. Clinical history, imaging variables, and electrocardiographic data were abstracted from the electronic medical records. Post-TAVR RBBB, defined as new onset RBBB in the postprocedure period, was manually verified by the study authors. The risks of PPM implantation (within 90-days post-TAVR) and mortality following TAVR were compared between patients with and without post-TAVR RBBB using the Kaplan-Meier method and Cox proportional hazards modeling. Out of 1992 patients included, 15 (0.75%) experienced new RBBB post-TAVR. There was a higher proportion of patients who had valve oversizing among patients with new RBBB post-TAVR versus not (17.9% versus 10.0%, p=0.034). There were no other significant differences in demographics or clinical characteristics between patients with and without post-TAVR RBBB including age at TAVR, sex, type of valve implanted, valve size, aortic valve calcium score, or left ventricular ejection fraction (Table 1). Ten patients (66.7%) with post-TAVR RBBB experienced high-grade atrioventricular block (≥2 consecutive blocked P waves) and subsequently underwent PPM implantation (median 4 days; interquartile range 1-90 days), compared to 268/1977 (13.6%) without RBBB (Figure 1). After adjustment for age, sex, balloon expandable valve, annulus diameter, and valve oversizing, post-TAVR RBBB was significantly associated with PPM implantation (hazard ratio [HR] 8.36, 95% confidence interval [CI] 4.19-16.7; p<0.001). No statistically significant increase in mortality was seen with post-TAVR RBBB (HR 0.83, 95% CI 0.33-2.11; p=0.69) following adjustment for age and sex. Although encountered rarely, post-TAVR RBBB was associated with an elevated risk of PPM implantation. The mechanisms for its development and its clinical prognosis require further study.Tabled 1Table 1: Baseline characteristics of study cohortMedian (IQR) or No. (%) of patientsVariableNNo RBBB (N=1977)New-Onset RBBB (N=15)P-valueAge at TAVR1,99281.3 (75.4, 86.0)82.6 (78.8, 87.4)0.45Sex (Males)1,9921,111 (56.2%)9 (60.0%)0.80Balloon Expandable Valve1,9921,744 (88.2%)12 (80.0%)0.41Valve size1,99226.0 (23.0, 29.0)26.0 (24.5, 29.0)0.49Annulus Area (cmˆ2) based on CT1,8504.7 (4.0, 5.4)4.6 (4.3, 5.1)0.81Annulus Diameter (mm)1,93027.0 (25.0, 29.1)26.0 (25.1, 28.8)0.87Valve Oversizing *1,85010.0 (3.0, 18.5)17.9 (15.4, 23.4)0.034LVEF (%)1,89762.0 (55.0, 66.0)61.5 (54.2, 67.8)0.97AV Peak Velocity1,8974.2 (4.0, 4.6)4.1 (4.0, 4.3)0.42AV Mean Gradient1,89743.0 (38.0, 51.0)41.5 (41.0, 44.8)0.76AV Area1,8970.8 (0.7, 0.9)0.9 (0.8, 1.0)0.33LVOT AV Velocity Ratio1,8970.2 (0.2, 0.2)0.2 (0.2, 0.3)0.47LVOT AV TVI Ratio1,8970.2 (0.2, 0.2)0.2 (0.2, 0.3)0.51LVOT Dimension1,7292.2 (2.1, 2.3)2.2 (2.1, 2.3)0.77LV Geometry9710.64Concentric Hypertrophy359 (37.4%)5 (45.5%)Concentric Remodeling264 (27.5%)2 (18.2%)Eccentric Hypertrophy158 (16.5%)3 (27.3%)Normal Geometry179 (18.6%)1 (9.1%)LVED Dimension1,55649.0 (45.0, 53.0)48.0 (43.0, 53.5)0.64Aortic Valve Calcium Score1,7302,281.0 (1,556.5, 3,169.5)2,729.0 (1,979.1, 3,480.5)0.31Myocardial Infarct1,987137 (6.9%)2 (13.3%)0.28Congestive Heart Failure1,987522 (26.5%)5 (33.3%)0.56Charlson Comorbidity Index1,9872.0 (0.0, 4.0)2.0 (1.0, 4.0)0.61STS Risk Score1,7304.8 (3.0, 8.0)4.0 (3.1, 9.2)0.86P-values result from a Wilcoxon rank sum test (continuous variables) or Fisher’s exact test (categorical variables). *Valve oversizing = (Nominal Area / Annulus area (mm)) -1) *100 AV – aortic valve; CT – computed tomography; IQR – interquartile range; LVEF – left ventricular ejection fraction; LVOT – left ventricular outflow tract; STS – Society of Thoracic Surgeons; TAVR – transcatheter aortic valve replacement; TVI - tissue velocity index Open table in a new tab