Disturbances in atrioventricular conduction and the additional need for a permanent pacemaker are recognized complications after transcatheter aortic valve replacement (TAVR). We analyzed the incidence of postprocedural conduction disorders and the need for permanent pacemaker implantation in patients undergoing TAVR with the Edwards SAPIEN valve. In 125 consecutive patients with symptomatic, severe aortic stenosis undergoing TAVR, a standard 12-lead electrocardiogram was obtained before and serially after the procedure. The cohort was divided into 2 groups with regard to the post-TAVR appearance of conduction disturbances, defined as left bundle branch block, right bundle branch block, fascicular hemiblock, atrioventricular block, and the need for a permanent pacemaker. The patients with and without conduction disturbances were compared. After TAVR, 19 patients (15.2%) met the study definition of a “new conduction defect” and 5 patients (4%) required a permanent pacemaker because of an advanced atrioventricular block. New left bundle branch block appeared in 5 patients (4%) and left anterior hemiblock in 9 (7.2%). No new right bundle branch block or left posterior hemiblock was observed. Although most baseline, echocardiographic, and procedural characteristics were equally distributed, the patients with new conduction disturbances more often had diabetes mellitus and peripheral vascular disease. Also, they more often were taking an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker, and the procedure was performed more often with apical access (12 [63.2%] vs 7 with femoral access [36.8%], p = 0.002). In conclusion, although the incidence of conduction disturbances was high after TAVR using the Edwards SAPIEN valve, with a significant increase in the rate of left bundle branch block and left anterior hemiblock, the need for permanent pacemaker implantation after TAVR with this valve remained low.
Percutaneous implantation without replacement of the valve is a promising alternative. In the randomized Placement of Aortic Transcatheter Valves (PARTNER) trial, high-risk patients with aortic stenosis who underwent transcatheter aortic valve replacement (TAVR) had better outcomes than those receiving medical treatment, and no inferiority was found compared to open surgical valve replacement with regard to safety. In addition to the PARTNER trial, centers in North America and Europe have reported encouraging clinical results with both types of aortic prostheses and both transfemoral and transapical approaches. Because of the proximity of the aortic valve to the conduction system, perivalvular tissue and calcific deposition in the aortic valve can produce electrocardiographic evidence of injury to the conduction system. Unsurprisingly, surgical aortic valve replacement can also produce such findings. Occasionally, permanent electronic pacing is required. The present study was undertaken to ascertain the frequency with which electrocardiographic evidence of conduction system injury was found after percutaneous implantation of an Edwards SAPIEN (Edwards Lifesciences, Irvine, California) aortic valve and to identify the factors associated with such appearance.
Methods
The study population consisted of 159 consecutive patients with severe symptomatic aortic stenosis who underwent percutaneous implantation of an Edwards SAPIEN aortic valve. All were participants in the PARTNER trial. Of those, 34 were excluded from the present analysis, because a permanent pacemaker was in place before TAVR in 31 and 3 died during the procedure. The remaining 125 patients formed the population for the present analysis (91 [72.8%] in cohort A and 34 [27.2%] in cohort B).
The clinical, electrocardiographic, echocardiographic, angiographic, and procedural details were prospectively recorded and entered into a registry by trained research personnel from the Cardiovascular Research Institute data center at MedStar Health Research Institute/MedStar Washington Hospital Center (Washington, DC). Data analysis and statistical support were also provided by that group. Every patient underwent right-sided heart catheterization and coronary arteriography before valve implantation. Those with coronary lesions underwent percutaneous coronary intervention when required.
For aortic valve placement, a 22F or 24F sheath was used for access to the femoral artery, and a 24F sheath was used for the apical approach. After arterial or intraventricular access, 10 to 70 U/kg of unfractionated heparin was administered. Before valve placement, balloon aortic valvuloplasty was performed. Positioning of the dilating balloon occurred during rapid ventricular pacing (about 180 beats/min). Subsequent placement of the prosthesis in the aortic annulus was guided by fluoroscopy, and the valve was deployed during rapid ventricular pacing. The final placement and function of the prosthesis was assessed by angiography and intraoperative transesophageal echocardiography.
An electrocardiogram was recorded before and serially after the procedure. The outcome variable of interest was the appearance of new conduction abnormalities during the procedure. Left bundle branch block (LBBB), right bundle branch block (RBBB), left anterior hemiblock (LAHB), left posterior hemiblock, and atrioventricular block requiring permanent pacing were defined according to the Electrocardiography and Arrhythmias Committee of the American Heart Association.
The development of permanent atrial fibrillation was also noted. According to the North American Society of Pacing and Electrophysiology/European Society of Cardiology International Consensus, permanent atrial fibrillation was defined as an episode lasting >1 year for which cardioversion failed to interrupt the arrhythmia for ≥24 hours. A conduction disturbance was defined as a composite variable including the development of advanced atrioventricular block requiring permanent pacemaker implantation, LBBB, RBBB, LAHB, or left posterior hemiblock.
For comparison, we divided the cohort into 2 groups. Group 1 consisted of 106 patients in whom no conduction disturbance appeared and group 2, the 19 patients in whom a disturbance appeared.
Statistical analysis was performed using the SAS, version 9.1, program (SAS Institute, Cary, North Carolina). Normally distributed continuous variables are expressed as the mean ± SD, and comparisons were made using Student’s t test. For those variables not normally distributed, the median and interquartile intervals are reported, and comparisons were made using the Wilcoxon rank sum test. Categorical variables are expressed as frequencies and percentages and were compared using the chi-square or Fisher’s exact test, as appropriate. Statistical significance was defined as a 2-sided p value <0.05. All the measurements were measured in their original scales.
Results
The baseline clinical characteristics are summarized in Table 1 . The advanced age (mean 84.2 years) of all 125 patients was noteworthy. Of those 125 patients, 19 (15.4%) developed conduction disturbances and 106 (84.6%) did not. The clinical characteristics were similar in both groups, except for greater rates of diabetes mellitus (p = 0.05) and peripheral vascular disease (p = 0.03) and a greater frequency of angiotensin-converting enzyme inhibitor/angiotensin II receptor blocker use (p = 0.02) in the conduction disturbance group. Because of the multiple comparisons, these differences could have occurred by chance.
| Variable | Conduction Disturbance | p Value | |
|---|---|---|---|
| No (n = 106) | Yes (n = 19) | ||
| Age (years) | 84.2 ± 6.2 | 84.2 ± 4.0 | 0.99 |
| Women | 63 (59.4%) | 12 (63.2%) | 0.76 |
| Society of Thoracic Surgeons score | 11.6 ± 4.1 | 11.6 ± 2.7 | 0.93 |
| Standard European System for Cardiac Operative Risk Evaluation | 13.3 ± 2.8 | 14.8 ± 3.2 | 0.06 |
| Logistic European System for Cardiac Operative Risk Evaluation | 39.5 ± 21.1 | 49.7 ± 24.1 | 0.07 |
| Cardiogenic shock | 2 (4.5%) | 0 | 1.00 |
| Body mass index (kg/m 2 ) | 27.7 ± 6.8 | 24.9 ± 5.7 | 0.09 |
| Diabetes mellitus | 31 (29.2%) | 10 (52.6%) | 0.05 |
| Systemic hypertension ⁎ | 99 (93.4%) | 19 (100.0%) | 0.59 |
| Hyperlipidemia † | 75 (70.8%) | 14 (73.7%) | 0.80 |
| Coronary artery disease ‡ | 55 (51.9%) | 10 (52.6%) | 0.95 |
| Chronic obstructive pulmonary disease | 27 (25.5%) | 4 (21.4%) | 0.78 |
| Renal failure (creatinine clearance <60 ml/min) | 77 (74.0%) | 17 (89.5%) | 0.24 |
| Previous stroke or transient ischemic attack | 29 (27.4%) | 5 (26.3%) | 0.93 |
| Previous coronary artery bypass grafting | 31 (29.2%) | 8 (42.1%) | 0.27 |
| Prior percutaneous coronary intervention | 16 (15.1%) | 4 (22.2%) | 0.50 |
| Peripheral vascular disease | 25 (23.6%) | 9 (47.4%) | 0.03 |
| β Blocker | 74 (69.8%) | 13 (68.4%) | 0.90 |
| Angiotensin-converting enzyme inhibitor/angiotensin receptor blocker | 52 (49.1%) | 15 (78.9%) | 0.02 |
| Digoxin | 6 (5.7%) | 3 (15.8%) | 0.14 |
| Statin | 69 (65.1%) | 15 (78.9%) | 0.24 |
⁎ History of hypertension diagnosed and/or treated with medication or current treatment with diet and/or medication by a physician.
† History of documented diagnosis of hypercholesterolemia and/or hypertriglyceridemia, treated with diet or medication.
‡ History of previous myocardial infarction, angina pectoris, or requirement of revascularization procedure (coronary artery bypass grafting or percutaneous transluminal coronary angioplasty).
The baseline echocardiographic parameters are listed in Table 2 . No significant differences were found. However, the left ventricular outflow tract diameter was insignificantly smaller in those who developed conduction disturbances. The baseline and postprocedure hemodynamic parameters are listed in Table 3 . The cardiac output was lower both before (p = 0.01) and after (p = 0.03) valve placement in those with new conduction disturbances. The hemodynamic response to valve replacement was virtually identical whether or not new conduction disturbances appeared.
| Variable | Conduction Disturbance | p Value | |
|---|---|---|---|
| No (n = 106) | Yes (n = 19) | ||
| Ejection fraction (%) | 52.6 ± 15.1 | 50.8 ± 13.4 | 0.63 |
| Moderate-to-severe calcified aortic valve | 77 (72.6%) | 13 (68.4%) | 0.78 |
| Left ventricular outflow tract diameter (mm) | 2.2 ± 2.1 | 1.9 ± 0.2 | 0.24 |
| Aortic valve area (cm 2 ) | 0.6 ± 0.1 | 0.6 ± 0.1 | 0.65 |
| Peak flow velocity (m/s) | 4.5 ± 0.7 | 4.2 ± 0.8 | 0.08 |
| Mean gradient (mm Hg) | 51.3 ± 16.0 | 47.0 ± 18.6 | 0.30 |
| Maximum gradient (mm Hg) | 80.0 ± 24.3 | 71.2 ± 26.4 | 0.15 |
| Pulmonary artery systemic pressure (mm Hg) | 50.1 ± 16.0 | 48.5 ± 16.4 | 0.70 |
| Variable | Conduction Disturbance | p Value | |
|---|---|---|---|
| No (n = 106) | Yes (n = 19) | ||
| Aortic valve area before (cm 2 ) | 0.6 ± 0.2 | 0.6 ± 0.2 | 0.63 |
| Aortic valve area after (cm 2 ) | 1.9 ± 0.2 | 2.0 ± 0.2 | 0.36 |
| Mean gradient before (mm Hg) | 46.0 ± 17.5 | 43.5 ± 13.7 | 0.55 |
| Mean gradient after (mm Hg) | 38.8 ± 45.4 | 31.7 ± 20.5 | 0.29 |
| Maximum gradient before (mm Hg) | 79.4 ± 23.8 | 75.6 ± 28.4 | 0.50 |
| Pulmonary artery systemic pressure before (mm Hg) | 50.1 ± 16.0 | 48.5 ± 16.4 | 0.70 |
| Pulmonary artery systemic pressure after (mm Hg) | 44.5 ± 13.4 | 42.2 ± 10.6 | 0.48 |
| Cardiac output before (l ml/min) | 3.5 ± 1.2 | 2.9 ± 0.8 | 0.01 |
| Cardiac output after (l ml/min) | 4.0 ± 1.2 | 3.3 ± 0.9 | 0.03 |
The TAVR details, emphasizing the size of the predilation balloon and the prosthetic valve relative to the echocardiographically measured size of the left ventricular outflow tract, are listed in Table 4 . No differences were found in the incidence of conduction disturbances with any of these parameters. The basic electrocardiographic measurements before and after TAVR are listed in Table 5 . The mean heart rate was faster after the procedure (p <0.001), and atrial fibrillation was present in an equal number of patients. The PR interval was shorter (p <0.001) and the QRS duration (p <0.001) and the rate-corrected QT interval (p <0.001) were somewhat longer. The preprocedure prevalence of conduction disturbances and the incidence of new abnormalities after TAVR are listed in Table 6 . Five patients developed an advanced atrioventricular block lasting >24 hours and required permanent pacing (placed 5 ± 1.41 days after the procedure). After 30 days, 2 still needed the pacemaker, and 1 patient had atrial fibrillation and RBBB. Two patients did not undergo follow-up examinations at our center. Of these 5 patients, 2 (40.0%) had had a RBBB before the procedure. Another 5 patients developed LBBB (1 patient with preprocedure LAHB and atrial fibrillation and the other 4 with basal sinus rhythm), and 9 developed LAHB. Thus, 19 developed the primary end point of the present analysis.
| Variable | Conduction Disturbance | p Value | |
|---|---|---|---|
| No (n = 106) | Yes (n = 19) | ||
| Balloon size (mm) | 20.1 ± 5.6 | 20.0 ± 0.1 | 0.35 |
| Valve size (23 mm) | 70 (66.0%) | 11 (57.9%) | 0.6 |
| Valve size (26 mm) | 36 (34.0%) | 8 (42.1%) | 0.6 |
| Apical access | 26 (68.4%) | 12 (31.6%) | <0.001 |
| Femoral access | 80 (92.0%) | 7 (8.0%) | <0.001 |
| Balloon/left ventricular outflow tract ratio | 1.01 ± 0.1 | 1.03 ± 0.1 | 0.36 |
| Valve size/left ventricular outflow tract ratio | 1.25 ± 0.12 | 1.20 ± 0.14 | 0.13 |
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