The aims of the present study were to investigate the incidence and characteristics of conduction disorders (CDs) after transcatheter aortic valve implantation (TAVI), to analyze the predictors of permanent pacemaker (PPM) implantation, and to evaluate the outcomes of CDs over time. In particular, we sought to investigate whether the depth of deployment and other technical aspects of valve implantation might predict the need for PPM implantation after TAVI. TAVI has been reported to favor the onset or worsening of CDs often requiring PPM implantation. A total of 70 patients with aortic stenosis due to dystrophic calcification underwent TAVI with third-generation CoreValve Revalving System from May 2007 to April 2009. We collected electrocardiograms at baseline, during TAVI, during hospitalization and at the 1-, 3-, 6-, and 12-month follow-up visits thereafter. The clinical, anatomic, and procedural variables were tested to identify the predictors of PPM implantation. The PPM dependency at follow-up was analyzed. Six patients were excluded from the analysis because of a pre-existing PPM. Of the 64 patients, 32 (50%) had one or more atrioventricular-intraventricular CDs at baseline. TAVI induced a worsening in the CDs in 49 (77%) of the 64 patients, with 25 (39%) requiring in-hospital PPM implantation. On multivariate analysis, the independent predictors of PPM implantation were the depth of the prosthesis implantation (p = 0.039) and the pre-existing right bundle branch block (p = 0.046). A trend in the recovery of the CDs over time was recorded, although 2 patients required PPM implantation 1 month after discharge for late complete atrioventricular block. In conclusion, TAVI often induces or worsens CDs, requiring PPM in more than one third of patients, although a trend in the recovery of CDs during the midterm was recorded. The independent predictors of PPM implantation were the depth of prosthesis implantation and pre-existing right bundle branch block.
The aim of the present study was to investigate the incidence and characteristics of conduction disorders (CDs) in patients undergoing transcatheter aortic valve implantation (TAVI) and the need for subsequent permanent pacemaker (PPM) implantation. In addition, to help identify the clinical, anatomic, and procedural predictors of postoperative PPM implantation and the outcome of CDs over time. In particular, we sought to investigate whether the depth of deployment and other technical aspects of valve implantation might predict the need for PPM implantation after TAVI.
Methods
The data from 70 consecutive patients with aortic valve stenosis undergoing TAVI at our Department at Padova University from May 2007 to April 2009 were analyzed. A total of 6 patients were excluded from the analysis because they already had undergone PPM implantation before TAVI. All patients were a part of the multicenter, expanded evaluation registry after conformité européenne mark approval. The inclusion and exclusion criteria for TAVI have been previously reported.
All procedures were performed using the third-generation self-expanding CoreValve Revalving System (Medtronic, Minneapolis, Minnesota), as previously described, using a transfemoral or transubclavian approach, according to the anatomy of the iliac and femoral arteries. Implantation success was defined as the correct positioning and performance of the prosthesis. Procedural success was defined as the success of implantation, with the patient leaving the catheterization laboratory alive. The good performance of the bioprosthesis was defined as a reduction in the mean transaortic gradient to <20 mm Hg and aortic regurgitation to ≤2+/4, as evaluated on an aortic angiogram or echocardiogram.
The degree of aortic valve calcium was scored according to the presence and extent of cusp calcification as it appeared on the aortic angiogram. The grading was as follows: grade 1, no calcification; grade 2, mild calcification appearing as a thin marginal rim in one or more cusps; grade 3, moderate calcification characterized by a thick rim occupying the entire surface of one or more cusps; and grade 4, severe calcification, defined as the presence of heavy calcification of all cusps or bulky calcification.
The depth of bioprosthesis implantation was measured in the right anterior oblique projection as the distance (in millimeters) of the aortic prosthesis within the left ventricular outflow tract, from the lower edge of the noncoronary cusp (D1) and from the lower edge of the left coronary cusp (D2) to the ventricular end of the prosthesis frame using quantitative angiographic digital techniques (Allura, Philips Medical System, Best, The Netherlands). The difference between D2 and D1 was calculated as the coaxial index. Prosthesis implantation was defined as coaxial when the coaxial index ranged from −1.0 mm to +1.0 mm and noncoaxial when the coaxial index was >+1.0 mm or <−1.0 mm. The ratio between the prosthesis nominal diameter and native annulus size was calculated as the prosthesis/annulus ratio. The ratio between the diameter of the deployed prosthesis measured at the level of the aortic annulus and the native aortic annulus was calculated as the prosthesis expansion index.
All patients underwent standard 12-lead electrocardiography before the procedure. To assess intraoperative CDs, 3-lead continuous electrocardiographic monitoring was recorded and electronically stored throughout the procedure. After the procedure, continuous monitoring was routinely performed in all patients during the hospital stay. Postoperatively, 12-lead electrocardiography was performed daily during hospitalization and at 1-, 3-, 6-, and 12-month follow-up visits thereafter to detect any modifications in the atrioventricular (AV) and intraventricular conduction. The analyses of the records were performed by an experienced electrophysiologist. The presence of CDs at any time was defined by the presence of at least one of the following abnormalities: first-, second-, or third-degree AV block, left bundle branch block (BBB), right BBB, and/or left anterior or posterior hemiblock. The currently accepted criteria were used to code for each of these CD. The requirement for PPM implantation was determined by the attending cardiologist according to the standardized criteria from the American College of Cardiology/American Heart Association/Heart Rhythm Society 2008 Guidelines for Device-Based Therapy of Cardiac Rhythm Abnormalities. All systems were implanted using a transvenous subclavian approach.
Follow-up data were collected at 1, 3, 6, and 12 months and yearly thereafter. Periprocedural death was defined as any death within 30 days after the procedure or any death before discharge. The clinical follow-up events included death from all causes, cardiac death (including all unexplained deaths), acute myocardial infarction, stroke, cardiac heart failure requiring rehospitalization, and PPM implantation. Moreover, at each temporal step, a 12-lead electrocardiogram was collected in all patients, to record modifications in AV and intraventricular conduction. In patients with a PPM, the percentage of ventricular pacing was detected by PPM interrogation. Moreover, to evaluate the PPM dependency in patients with a paced baseline electrocardiogram, the pacemaker was programmed to VVI at the lowest rate possible and the underlying rhythm was obtained. The patients were considered pacemaker dependent if they continued to be paced or had complete AV block or atrial fibrillation with inadequate ventricular response. The patients were considered as nonpacemaker dependent if they had sinus rhythm or atrial fibrillation with an adequate ventricular response.
The categorical data are expressed as numbers and percentages and compared by Fisher’s or chi-square exact test as appropriate. The continuous variables are expressed as the mean ± SD and compared using Student’s t test. The preoperative clinical variables, anatomic characteristics, and procedural data thought likely to influence the conducting system were tested by univariate logistic regression analysis to determine the predictors of postoperative PPM implantation. This model included all the variables with a biologically relevant correlation to the onset of CD: age, gender, anatomic characteristics (e.g., aortic valve area, calcium score, aortic regurgitation, left ventricular mass index), effects of drugs (type of anesthesia), technical aspects that might mechanically effect the conduction system (e.g., valvuloplasty balloon diameter, prosthesis size, prosthesis/annulus diameter ratio, need for postdilation, depth of implantation, prosthesis expansion index, and valve-in-valve), all pre-existing CDs (AV block I, left BBB, anterior hemiblock, posterior hemiblock, right BBB, bifascicular block). Multiple stepwise logistic regression analyses of those significant variables (p <0.10) on univariate analysis were performed to identify independent predictors of PPM implantation. Univariate and multivariate analyses were also performed considering the same variables to identify predictors of worsening in CDs. The odds ratios and their corresponding 95% confidence intervals are provided. A p value of <0.05 with a 2-tailed test was considered statistically significant. Statistical analysis was performed using the statistical software Statistical Package for Social Sciences, version 17.0, for Windows (SPSS, Chicago, Illinois).
Results
The baseline characteristics were similar between those patients who required PPM implantation and those who did not ( Table 1 ). Implantation success was achieved in 62 (97%) of the 64 patients, with procedural success in 61 (95%) of 64. The procedural data were similar between those who required PPM implantation and those who did not, except for the depth of prosthesis implantation measured from the lower edge of the noncoronary cusp (D1), which was significantly deeper (i.e., more ventricular) in the patients who underwent PPM implantation than in those who did not. Also, the hospital stay was longer in patients who underwent PPM implantation ( Table 2 ).
| Variable | Total (n = 64) | PPM After TAVI (n = 25) | No PPM After TAVI (n = 39) | p Value |
|---|---|---|---|---|
| Age (years) | 0.567 | |||
| Mean ± SD | 80.97 ± 6.55 | 81.56 ± 5.10 | 80.59 ± 7.37 | |
| Range | 55–91 | |||
| Men | 29 (45%) | 15 (60%) | 14 (36%) | 0.058 |
| Logistic EuroSCORE | 0.464 | |||
| Mean ± SD | 23.64 ± 14.72 | 25.47 ± 15.70 | 22.66 ± 14.00 | |
| Range | 3–71 | |||
| New York Heart Association | 0.719 | |||
| I | 9 (14%) | 2 (8%) | 7 (18%) | |
| II | 19 (30%) | 8 (32%) | 11 (28%) | |
| III | 32 (50%) | 13 (52%) | 19 (49%) | |
| IV | 4 (6%) | 2 (8%) | 2 (5%) | |
| Canadian cardiovascular society | 0.629 | |||
| 0 | 39 (61%) | 17 (68%) | 22 (56%) | |
| 1 | 2 (3%) | 1 (4%) | 1 (3%) | |
| 2 | 6 (9%) | 3 (12%) | 3 (8%) | |
| 3 | 10 (16%) | 2 (8%) | 8 (21%) | |
| 4 | 7 (11%) | 2 (8%) | 5 (13%) | |
| Calcium score | 0.595 | |||
| ≤2 | 17 (27%) | 8 (32%) | 9 (23%) | |
| 3 | 30 (47%) | 10 (40%) | 20 (51%) | |
| 4 | 17 (27%) | 17 (28%) | 10 (26%) | |
| Coronary artery disease | 40 (63%) | 17 (71%) | 23 (61%) | 0.586 |
| Congestive heart failure | 30 (47%) | 13 (52%) | 17 (44%) | 0.511 |
| Cerebral vascular accident | 7 (11%) | 2 (8%) | 5 (13%) | 0.547 |
| Chronic kidney disease | 35 (55%) | 17 (68%) | 18 (46%) | 0.087 |
| Chronic obstructive pulmonary disease | 14 (22%) | 7 (29%) | 7 (18%) | 0.298 |
| Peripheral vascular disease | 22 (34.4%) | 8 (32.0%) | 14 (35.9%) | 0.749 |
| Previous cardiac surgery | 16 (25.0%) | 9 (36%) | 7 (17.9%) | 0.104 |
| Neurologic dysfunction | 10 (15.6%) | 3 (12%) | 7 (17.9%) | 0.523 |
| Liver cirrhosis | 5 (7.8%) | 1 (4%) | 4 (10.3%) | 0.363 |
| Porcelain aorta ⁎ | 15 (23.4%) | 3 (12%) | 12 (30.8%) | 0.084 |
| Hostile thorax † | 9 (14.1%) | 3 (12.0%) | 6 (15.4%) | 0.704 |
| Aortic valve area (cm 2 ) | 0.78 ± 0.21 | 0.80 ± 0.20 | 0.77 ± 0.22 | 0.544 |
| Ejection fraction (%) | 52.32 ± 13.24 | 51.68 ± 12.95 | 52.74 ± 13.58 | 0.759 |
⁎ Defined as an aorta with diffuse, circumferential, plate-like calcification involving the whole proximal ascending aorta, precluding cannulation or cross-clamping.
† Included patients with a severe deformity of the thorax, severe connective tissue disease, and previous mediastinal/thorax radiotherapy.
| Variable | Total (n = 64) | PPM After TAVI (n = 25) | No PPM After TAVI (n = 39) | p Value |
|---|---|---|---|---|
| Procedural success | 61 (95%) | 23 (92%) | 38 (97%) | 0.315 |
| General anesthesia | 15 (23%) | 8 (33%) | 7 (18%) | 0.360 |
| Double-lumen intubation | 8 (13%) | 3 (12%) | 5 (13%) | 0.419 |
| Transesophageal echocardiography | 13 (20%) | 6 (27%) | 7 (21%) | 0.604 |
| Access | ||||
| Transfemoral | 60 (94%) | 22 (88%) | 38 (97%) | 0.128 |
| Transubclavian | 4 (6%) | 3 (12%) | 1 (3%) | |
| Prosthesis size (mm) | ||||
| 26 | 36 (56%) | 12 (48%) | 24 (62%) | 0.287 |
| 29 | 28 (44%) | 13 (52%) | 15 (39%) | |
| Predilation | 62 (97%) | 24 (96%) | 38 (97%) | 0.747 |
| Postdilation | 19 (30%) | 6 (24%) | 13 (33%) | 0.425 |
| Valve-in-valve | 5 (8%) | 3 (12%) | 2 (5%) | 0.318 |
| Prosthesis/annulus diameter ratio | 1.21 ± 8.89 | 1.20 ± 1.05 | 1.21 ± 7.80 | 0.561 |
| Depth of implantation (mm) | ||||
| D1 | 10.25 ± 3.39 | 11.34 ± 3.62 | 9.50 ± 3.04 | 0.031 |
| D2 | 11.41 ± 3.27 | 12.16 ± 3.25 | 10.89 ± 3.23 | 0.108 |
| Coaxial index (mm) | 1.15 ± 1.59 | 0.81 ± 1.47 | 1.39 ± 1.64 | 0.155 |
| Noncoaxial alignment | 44 (69%) | 15 (58%) | 29 (76%) | 0.114 |
| Prosthesis expansion index | 0.93 ± 0.11 | 0.93 ± 0.11 | 0.93 ± 0.12 | 0.727 |
| Procedural duration (minutes) | 72.7 ± 37.6 | 72.52 ± 28.33 | 72.74 ± 42.79 | 0.982 |
| Hospital stay (days) | 12.34 ± 8.37 | 15.27 ± 11.06 | 10.24 ± 5.24 | 0.022 |
Of the 64 patients, 32 (50%) had one or more degrees of AV-intraventricular CDs before TAVI, including first degree AV block (n = 15), complete left BBB (n = 9), right BBB (n = 8), anterior hemiblock (n = 11), and posterior hemiblock (n = 2; Table 3 ).
| Variable | Before TAVI | After TAVI | Last Follow-Up (6.0 ± 4.2 mo) | p Value | ||
|---|---|---|---|---|---|---|
| Before Versus After TAVI | After TAVI Versus Last Follow-Up | Before TAVI Versus Last Follow-Up | ||||
| Atrial fibrillation | 10/64 (16%) | 11/64 (17%) | 10/57 ⁎ (18%) | 0.705 | 0.655 | 0.655 |
| Left bundle branch block | 9/64 (14%) | 37/64 (58%) | 25/57 ⁎ (44%) | <0.0001 | 0.108 | <0.0001 |
| Right bundle branch block | 8/64 (13%) | 3/64 (5%) | 2/57 ⁎ (4%) | 0.059 | 0.317 | 0.046 |
| Anterior hemiblock | 11/64 (17%) | 3/64 (5%) | 4/57 ⁎ (7%) | 0.005 | 0.317 | 0.034 |
| Posterior hemiblock | 2/64 (3%) | 2/64 (3%) | 1/57 ⁎ (2%) | 1.000 | 0.317 | 1.000 |
| PR interval (ms) | 182.9 ± 5.7 | 211.1 ± 5.5 | 182.7 ± 29.9 | <0.0001 | <0.0001 | 0.761 |
| QRS width (ms) | 103.6 ± 4.1 | 144.3 ± 3.6 | 125.3 ± 26.3 | <0.0001 | <0.0001 | <0.0001 |
| QT (ms) | 406.2 ± 45.7 | 424.4 ± 47.7 | 411.5 ± 30.0 | 0.028 | 0.039 | 0.486 |
⁎ Three cases of periprocedural mortality and four with paced rhythm without adequate ventricular response during PPM inhibition excluded because analysis was not applicable.
After TAVI, worsening or new-onset CD appeared in most patients (77%). Left BBB was the most frequent new CD, appearing in 28 patients (44%), isolated or associated to new first-degree AV block ( Table 3 ). A complete AV block appeared in 19 patients ( Figure 1 ). During the hospitalization, 25 patients (39%) underwent PPM implantation. The indications for PPM implantation were permanent or transient complete AV block in 16, second-degree AV block associated with left BBB in 6, sick sinus syndrome in 1, and trifascicular block in 1 patient. Indeed, 1 patient who did not have any CD before TAVI underwent PPM implantation because of the development of first-degree AV block associated with new left BBB after TAVI, with progressive prolongation of PR and QRS intervals during hospital stay. Of the 25 patients requiring PPM implantation, 9 had no AV or intraventricular CD before TAVI, and 16 patients showed at least one CD ( Figure 2 ).
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