A total of 707 patients underwent TAVI at the 2 participating centers between May 2010 and December 2015, and 554 of them underwent a balloon-expandable valve implantation. Exclusion criteria consisted of self-expandable valve implantation (n=153), a pre-existing PPM (n=82), left bundle branch block (LBBB) (n=41), right bundle branch block (n=52), transient CA detected during a 24-hour electrocardiogram monitoring prior to TAVI (n=9), and a valve-in-valve procedure (n=23). The final study population consisted of 347 patients. Continuous electrocardiogram recording during the procedure was performed in a subgroup of 75 consecutive patients between February 2013 and November 2015 who underwent a TAVI procedure including BAV step in 1 of the 2 study centers.

Indications for TAVI and the approach were determined by local Heart Teams and data were prospectively gathered in local datasets. Outcomes were defined according to the Valve Academic Research Consortium-2 criteria.11 Patients signed informed consent forms before the procedure.

The TAVI procedures were performed with the balloon-expandable valve SAPIEN XT or SAPIEN 3 (Edwards Lifesciences, Irvine, California, United States) as previously reported.12,13 The decision to perform BAV prior to valve implantation was left at operator's discretion. In the case of BAV, moderate BAV under rapid pacing with an undersized balloon was used in all cases.

A 12-lead electrocardiogram was obtained upon hospital admission in all patients. Continuous electrocardiogram recording during TAVI procedures was carried-out using a 2-limb lead electrocardiogram. In addition, in a subgroup of 75 consecutive patients undergoing TAVI in 1 of the 2 study centers, a 6-limb lead electrocardiogram was recorded immediately before TAVI, and immediately after each of the following procedural steps: placement of the stiff-wire in the left ventricle, BAV, valve implantation, and valve postdilation or implantation of a second valve if needed. In addition, any new CA was recorded at the time of occurrence (any time during the procedure). A 12-lead electrocardiogram was recorded immediately post-TAVI and daily until hospital discharge and all patients were under continuous electrocardiogram monitoring for at least 72hours postprocedure.

All electrocardiograms were prospectively analyzed by a cardiologist at each center. Diagnosis of new conduction disturbances was based on the recommendations of the American Heart Association/American College of Cardiology Foundation/Heart Rhythm Society for the standardization and interpretation of electrocardiograms.14 Indications for PPM were in accordance with current recommendations.15 Transient new-onset LBBB was defined as a new LBBB that resolved before the 1-month follow-up. Atrioventricular block (AVB) resolution in patients receiving a PPM was defined as a ventricular pacing<1% at 1-month follow-up.16

Patients were followed up through outpatient visits at 1-month follow-up. A 12-lead electrocardiogram was obtained in all patients. In addition, ventricular pacing rates were evaluated in patients receiving a PPM post-TAVI.

Data are expressed as mean±standard deviation or median [interquartile range] for continuous variables and as numbers and percentages for categorical variables. Continuous variables were compared using the 2-sided Student t test and Mann-Whitney U test, according to the normality of the distribution. Categorical variables were compared using the chi-square or Fisher exact test as appropriate. A P value<.05 was considered significant. Analyses were conducted using the Statistical Package for Social Sciences version 22 (SPSS Inc, IBM, Armonk, New York, United States).

The main baseline characteristics of the 75 patients with continuous electrocardiogram procedural monitoring/recording are displayed in Table 1. A total of 75 CA occurred in 58 (77.3%) patients during the hospitalization period. The types of CA are detailed in Table 2. New-onset LBBB occurred in 48 (64%) patients and a third-degree AVB in 16 (21.3%) patients. The timing of onset of LBBB and third-degree AVB are shown in Figure 1. Up to 54.2% of new-onset LBBB and 43.7% of third-degree AVB episodes occurred before valve implantation.

Figure 1.

Timing of conduction abnormalities during TAVI procedure. Number of patients with new LBBB and third-degree AVB at each step of the TAVI procedure. AVB, atrioventricular block; LBBB, left bundle branch block; TAVI, transcatheter aortic valve implantation.

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Persistent new-onset LBBB or unresolved AVB requiring PPM implantation before hospital discharge occurred in 25 of 75 patients, 46.3% of patients with a new LBBB or third-degree AVB related to the TAVI procedure. The occurrence of CA before valve implantation (during wire manipulation or BAV) tended to be associated with a higher rate of persistent LBBB or unresolved AVB at hospital discharge (54.5 vs 31.8%, P=.097). At 1-month follow-up, 18 out of 74 patients (24.3%) with complete follow-up (33.3% of patients with new-onset LBBB or third-degree AVB) had a persistent LBBB or unresolved AVB with a ventricular pacing>1% of the time. The occurrence of CA before valve implantation was not associated with a higher rate of persistent CA at 1-month follow-up (39.4 vs 23.8%; P=.236) (Figure 2A).

Figure 2.

Persistence of conduction abnormalities over time. Number of patients with new-onset LBBB or unresolved AVB (A) and new-onset LBBB (B) at each time point according to its onset before or after valve implantation. AVB, atrioventricular block, FU, follow-up; LBBB, left bundle branch block, VI, valve implantation. aP=.097. bP=.236. cP=.028. dP=.054.

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Up to 60.4% of new LBBB occurring during the procedural time resolved during the hospitalization period, most of them (86.2%) within the first 24hours following TAVI. Among the 19 (39.6%) patients with persistent LBBB upon hospital discharge, in 6 (31.6%) patients there was LBBB resolution at 1-month follow-up. The persistence of LBBB over time according to the timing of onset (before or after valve implantation) is shown in Figure 2B. LBBB persisted more frequently at hospital discharge (53.8 vs 22.7%; P=.028) and at the 1 month follow-up (38.5 vs 13.6%; P=.054) when occurring before valve implantation.

The onset of the new CA occurred after the procedure in 6 patients: 3 (18.75%) third-degree AVB and 3 (6.25%) new LBBB. These third-degree AVBs occurred during the first 24hours after the procedure, and 2 of them were persistent at 30-days follow-up. In the 3 patients with a new LBBB after the procedure, only 1 of them occurred after the first 24hours. In 2 patients, the LBBB was associated with other CA leading to PPM implantation and showed persistent LBBB or unresolved AVB at 30-days follow-up.

Nine patients received a PPM during the hospitalization period. The reasons for PPM were complete AVB in 8 (88.8%) patients and new-onset LBBB and first-degree AVB in 1 patient. No differences were observed in the rate of unresolved AVB requiring PPM implantation regarding its timing of onset (57.1% before vs 44.4% after valve implantation; P=.50). All second-degree AVBs were transient. At 1-month follow-up, the mean rate of ventricular pacing in patients requiring PPM before hospital discharge was of 82.7±34.5%. Atrioventricular block resolution with a ventricular pacing<1% occurred in 1 patient, without differences between those occurring before and those after valve implantation (25% vs 0%; P=.50).

A total of 264 out of 347 (76.1%) patients underwent TAVI with BAV preceding valve implantation, and 83 (23.9%) patients underwent direct TAVI. The main baseline clinical characteristics and echocardiographic and procedural findings of the study population according to the use of BAV are shown in Table 3. Patients in the direct TAVI group were older (82±7 vs 80±8 years; P=.019), had a higher left ventricular ejection fraction (60±13 vs 56±14%; P=.037), underwent TAVI more frequently using the transfemoral approach (89.2 vs 74.3%; P=.004), and more frequently received a SAPIEN 3 valve (20.5 vs 8.3%; P=.002).

New-onset LBBB persistent at hospital discharge was observed in 57 (16.4%) patients, 16 (19.3%) in the direct TAVI group and 41 (15.5%) in the BAV group prior to valve implantation group (P=.45). In addition, 32 (9.2%) patients required PPM implantation after TAVI without differences between groups (direct TAVI: 9.6%, BAV prior to TAVI: 9.1%; P=.91) (Table 4). The reasons for PPM were third-degree AVB in 22 (68.7%) patients, new first-degree AVB and LBBB in 3 (9.4%) patients, second-degree AVB in 2 (6.2%) patients, intermittent LBBB and right bundle branch block in 2 (6.2%) patients, slow atrial flutter in 1 (3.1%) patient, and sinus node dysfunction with severe bradycardia in 2 (6.2%) patients. Overall, 77 (22.2%) patients had a persistent LBBB or third-degree AVB requiring PPM implantation without significant differences between groups (direct TAVI: 25.3%, BAV prior to TAVI: 21.2%; P=.434) (Table 4). There were 4 in-hospital deaths and 6 patients did not complete the 1 month follow-up visit. At 1-month follow-up, 45 patients had persistent LBBB or unresolved third-degree AVB with a ventricular pacing rate>1%, 10 (47.6%) in the direct TAVI group and 35 (76.1%) in the BAV prior to TAVI group, P=.021 (Figure 3). The main baseline clinical characteristics and echocardiographic and procedural findings of patients with new CA according to resolution of the CA at 1-month follow-up are shown in Table 5. These results did not change when differences between the BAV and direct TAVI groups (age, left ventricular ejection fraction, chronic obstructive pulmonary disease, transfemoral approach, and SAPIEN 3 device) were entered into a multivariate model. The electrocardiograms of patients with persistent CA tended to show a longer PR and QRS duration, but these differences were not statistically significant (175.4±26.3 vs 195.7±40.6; P=.114) and (93.8±9.3 vs 99.3±18.3; P=.288), respectively. The use of BAV prior to TAVI was the only factor associated with a lack of resolution of the CA (persistent LBBB or unresolved third-degree AVB with a ventricular pacing rate>1%) at 1-month follow-up (OR, 3.5; 95%CI, 1.17-10.43; P=.021).

Figure 3.

Persistent conduction abnormalities at 1-month follow-up according to the use of BAV prior to valve implantation. Rates of persistent LBBB or unresolved AVB with a ventricular pacing>1% and persistent LBBB at 1-month follow-up in patients undergoing BAV before valve implantation vs direct TAVI. AVB, atrioventricular block; BAV, balloon aortic valvuloplasty; LBBB, left bundle branch block; TAVI, transcatheter aortic valve implantation.

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At 1-month follow-up, LBBB persisted in 34 (64.1%) patients discharged with a new-onset LBBB: 7 (43.7%) patients in the direct TAVI group and 27 (73%) patients in the BAV prior to TAVI group, P=.042 (Figure 3).

The main limitation of this study is its small sample size. However, this was due in part to the exclusion of patients with pre-existing CA. In addition, this study currently represents the largest study with continuous electrocardiogram monitoring and systematic electrocardiogram recording during the TAVI procedure. The choice of direct TAVI or BAV preceding TAVI was not randomized, and we cannot exclude the influence of potential confounders on the results obtained. Two different generations of balloon-expandable valves (SAPIEN XT and SAPIEN 3), which might have a different impact on CA, were used. Although the direct TAVI strategy was more frequently used in patients receiving a SAPIEN 3 valve, the groups of persistent CA were well-balanced with respect to this variable.