Background
Transcatheter aortic valve implantation (TAVI) is an alternative to conventional surgery in high-risk patients with severe aortic stenosis (AS), but data regarding mitral regurgitation (MR) characteristics and changes after TAVI are sparse.
Methods
A total of 254 patients with severe AS referred for TAVI were prospectively enrolled. Comprehensive echocardiography was performed at baseline and at 7 days and 1 month in patients who underwent TAVI. MR was semiquantitatively graded from 0 to 4. Overlap of the anterior mitral leaflet and the device was measured using transesophageal echocardiography immediately after TAVI.
Results
At screening, MR was absent in 26%, grade 1 in 44%, grade 2 in 25%, and grade ≥3 in 5% and was organic in 68% and functional in 32%. TAVI was finally performed using the Edwards Sapien valve in 119 patients, including four with MR grade ≥ 3. MR grade significantly decreased at 7 days ( P = .003) but remained unchanged at 1 month ( P = .55), whereas reverse remodeling occurred only at 1 month (improvements in left ventricular [LV] end-systolic diameter and ejection fraction; P < .05 for both). MR changes over time significantly differed according to ejection fraction and LV diameters (all P values for interaction < .005) but not according to aortic mean gradient, MR etiology, or overlap of the anterior mitral leaflet and the device (all P values for interaction > .15).
Conclusions
In patients referred for TAVI, MR is common, mainly organic, and rarely severe. After TAVI, MR improved within 7 days in both organic and functional MR, was not influenced by overlap of the anterior mitral leaflet and the device, but was associated with improvement in LV ejection fraction. Possible MR improvement should be taken into account in patient selection for TAVI especially, in cases of LV dysfunction or enlargement and MR of borderline severity.
In patients undergoing aortic valve replacement (AVR) for severe aortic stenosis (AS), mitral regurgitation (MR) is a common associated finding that negatively affects outcomes. However, after AVR, MR is susceptible to decrease because of left ventricular (LV) reverse remodeling. In patients at high risk for surgery, transcatheter aortic valve implantation (TAVI) has emerged as an alternative to conventional surgery. In this population of elderly patients with severe comorbidities and often reduced ejection fractions (EFs), MR etiologies and changes after TAVI have never been specifically evaluated. To date, data regarding MR characteristics and changes in patients undergoing TAVI are sparse, and previous studies were impeded by small sample sizes and an absence of homogenous MR evaluation and have led to contradictory results. Furthermore, the impact of the interaction between the anterior mitral leaflet (AML) and the device on MR changes remains unclear. Thus, we aimed to describe MR characteristics and changes in a large population of patients referred for TAVI.
Methods
Population
From October 2006 to October 2009, patients referred to our department for the evaluation and management of severe symptomatic AS and who were considered potential candidates for TAVI were prospectively enrolled. The screening included clinical evaluation, transthoracic and if necessary transesophageal echocardiography, coronary angiography, aortic and femoroiliac angiography, and multislice computed tomography. The decision to perform TAVI was taken by a multidisciplinary medicosurgical team on the basis of surgical risk (contraindications to or high risk for conventional AVR as generally reflected by a European System for Cardiac Operative Risk Evaluation score ≥ 20% or Society of Thoracic Surgeons predicted risk of mortality ≥ 10%), life expectancy (>1 year), anatomy (suitable aortic annular diameter [18–25 mm], tricuspid aortic valve, and absence of bulky calcifications close to the coronary ostia or LV thrombus) and if there was no need for surgical coronary artery revascularization.
TAVI Procedure
The transfemoral approach was considered the first option, and the transapical approach was used when contraindications to the transfemoral access were present (femoroiliac diameter ≤ 6–9 mm according to the device used, severe calcifications or tortuosity, previous aortofemoral bypass, bulky aortic atherosclerosis). The balloon-mounted Edwards Sapien valve (Edwards Lifesciences, Irvine, CA) was used. Procedures were performed in the catheterization laboratory, or operating room, under general anesthesia and both fluoroscopic and transesophageal echocardiographic guidance.
Echocardiography
All patients underwent comprehensive transthoracic echocardiography at baseline using a high-end, commercially available ultrasound system (iE33, Philips Medical Systems, Andover, MA; Vivid 7, GE Vingmed Ultrasound AS, Horten, Norway; or Sequoia C512, Siemens Medical Systems, Erlangen, Germany) using regular clinical settings. Assessment of AS severity was based on aortic mean gradient and aortic valve area. LV diameters were measured using M-mode imaging and left atrial area in the four-chamber apical view. EF was visually assessed. Systolic pulmonary artery pressure was estimated using peak tricuspid regurgitation velocity. MR degree was assessed on the basis of the integration of color Doppler jet area, vena contracta, and proximal isovelocity surface area and graded from 0 to 4 (0 = no MR, 1 = mild MR, 2 = mild to moderate MR, 3 = moderate to severe MR, 4 = severe MR). Examples of MR severity are presented in Figure 1 . Jet area was measured in the apical view as the largest color jet. The vena contracta was measured perpendicularly to the jet in parasternal long-axis or apical view. Proximal isovelocity surface area was measured in the most appropriate incidence to obtain a flow convergence parallel to the ultrasound beam. The degree of mitral calcification (leaflets and annulus) was semiquantitatively graded (none, mild, moderate, or severe). MR etiology was classified as organic if MR was due to prolapse, calcification, rheumatic, or endocarditic lesions and functional in the case of an absence of mitral valve abnormalities with valve tethering and incomplete closure. During the procedure, transesophageal echocardiography was used to verify the correct positioning of the catheter, guidewire, and device and to detect complications. AML-device overlap, defined as the distance between the insertion of the AML and the most apical extent of the prosthesis, was measured immediately after implantation in the long-axis view (120°; Figure 2 ). Comprehensive transthoracic echocardiography was performed at 7 days and 1 month at the implanting center. Degree of aortic regurgitation after TAVI was also semiquantitatively assessed as previously reported. All echocardiograms were reviewed by the two first authors. MR grading was performed separately, and consensus was reached in case of discrepancy. Interobserver variability was good (κ = 0.85).
Statistical Analysis
Data are presented as mean ± SD, median (interquartile range), or percentages as appropriate. Comparisons of patients who ultimately underwent TAVI and those who did not were performed using t tests or χ 2 tests as appropriate. Comparisons of echocardiographic parameters according to MR etiology also used t tests or χ 2 tests as appropriate. Among the patients undergoing TAVI, comparisons of the echocardiographic characteristics before and 7 days after TAVI and before and 1 month after TAVI used paired t tests. Comparisons of MR changes between time periods used paired t tests. In patients who completed all examinations, evaluation of MR degree over time was analyzed using repeated-measures analysis of variance, taking into account MR severity at baseline, 7 days, and 1 month. Interaction testing was used to analyze the effect of baseline characteristics on the evolution pattern of MR. P values < .05 were considered statistically significant.
Results
Baseline Characteristics of Patients Screened for TAVI
Between October 2006 and October 2009, 254 patients were referred to our institution for TAVI. Clinical and echocardiographic characteristics are presented in Table 1 . The mean age was 82 ± 8 years, and 123 (48%) were women. All patients had severe AS (mean aortic valve area, 0.7 ± 0.2 cm 2 ; mean gradient, 47 ± 17 mm Hg). The mean EF was 48 ± 14% (range, 15%–70%). MR was absent in 67 patients (26%), grade 1 in 112 (44%), grade 2 in 63 (25%), grade 3 in 10 (4%), and grade 4 in two (1%). Organic MR was observed in 127 patients (68%) and functional MR in 60 (32%). Mechanisms of organic MR were leaflet calcifications in 84 patients (66%), leaflet thickening in 34 (27%), and valve prolapse in nine (7%). Patients with organic MR presented with higher EFs (53 ± 11% vs 33 ± 12%, P < .0001), smaller mitral annular diameters (39 ± 5 vs 42 ± 4 mm, P = .009), and more frequent annular calcifications (98 patients [77%] vs 24 patients [40%], P < .0001).
| Variable | Overall ( n = 254) | TAVI ( n = 119) | No TAVI ( n = 135) | P |
|---|---|---|---|---|
| Age (y) | 82 ± 8 | 82 ± 8 | 83 ± 8 | .50 |
| Women | 123 (48%) | 56 (47%) | 67 (50%) | .68 |
| European System for Cardiac Operative Risk Evaluation score (%) | 28 ± 16 | 28 ± 15 | 29 ± 17 | .81 |
| Aortic valve area (cm 2 ) | 0.7 ± 0.2 | 0.7 ± 0.2 | 0.7 ± 0.2 | .23 |
| Mean transaortic gradient (mm Hg) | 47 ± 17 | 50 ± 16 | 45 ± 17 | .02 |
| Systolic pulmonary artery pressure (mm Hg) | 49 ± 14 | 49 ± 14 | 49 ± 14 | .86 |
| LV end-diastolic diameter (mm) | 51 ± 9 | 49 ± 8 | 52 ± 10 | .04 |
| LV end-systolic diameter (mm) | 36 ± 12 | 34 ± 10 | 38 ± 13 | .01 |
| LV EF (%) | 48 ± 14 | 49 ± 13 | 47 ± 16 | .20 |
| MR grade | .67 | |||
| 0 | 67 (26%) | 29 (24%) | 38 (28%) | |
| 1 | 112 (44%) | 52 (44%) | 60 (44%) | |
| 2 | 63 (25%) | 34 (28%) | 29 (22%) | |
| 3 | 10 (4%) | 3 (3%) | 7 (5%) | |
| 4 | 2 (1%) | 1 (1%) | 1 (1%) | |
| Organic MR | 127 (68%) | 67 (74%) | 60 (62%) | .02 |
Treatment Strategy
Ultimately, 119 patients underwent TAVI using the Edwards Sapien valve, whereas 10 received Medtronic CoreValve devices (because of aortic annular diameters > 25 mm; Medtronic, Inc., Minneapolis, MN), 33 patients were redirected toward surgical AVR, and 92 remained on medical therapy because of technical contraindications to TAVI, life expectancy estimation < 1 year, severe mental deterioration, frailty, or refusal. Seventy-one patients (60%) were treated via the transfemoral approach and 48 (40%) via the transapical approach. A 26-mm prosthesis was used in 78 patients and a 23-mm prosthesis in 41 patients. Baseline characteristics of the patients who underwent TAVI and of those who did not are presented in Table 1 .
Among the 12 patients with MR grade ≥ 3, TAVI was performed in four patients (one patient with MR grade 4 and three patients with MR grade 3). MR etiology was functional in three patients and organic in one, considered inoperable. Among the remaining eight patients (five with organic MR and three with functional MR), two were redirected toward surgery (one because of small femoral artery diameters, the second because of severe left main stenosis) without associated mitral valve surgery, and six patients were conservatively managed (one for active cancer, one for extremely severe left ventricular dysfunction, two for severe neurologic dysfunction, one because of death during screening, and one for refusal of any procedure).
MR Changes in Patients Who Underwent TAVI Using the Edwards Sapien Prosthesis
Among the 119 patients who underwent TAVI with the Edwards Sapien valve, MR was absent at baseline in 29 patients (24%), grade 1 in 52 (44%), grade 2 in 34 (28%), and grade ≥ 3 in four (4%) ( Table 1 ). MR etiology was organic in 67 patients (74%) and functional in 23 (26%). Mean AML-device overlap, as assessed during transesophageal echocardiography immediately after TAVI completion, was 6 ± 2 mm (range, 1–15 mm).
Fifteen patients died during the first week after TAVI, including the patient with MR grade 4, and echocardiographic follow-up was available at 7 days in 95% of survivors (99 of 104). As expected, aortic valve area significantly increased and mean gradient significantly decreased. LV diameters and EF did not change, whereas MR significantly decreased ( P = .003; Table 2 ). Changes in MR degree are detailed in Figure 3 A. MR remained unchanged in 60 of 99 patients (61%), decreased in 28 (28%, most cases from grade 1 to grade 0), and increased in 11 (11%, most cases from grade 1 to grade 2).
| Parameter | Before TAVI ( n = 119) | 7 Days after TAVI ( n = 99) | 1 Month after TAVI ( n = 60) | P Value, before vs 7 Days after TAVI | P Value, 7 Days vs 1 Month after TAVI |
|---|---|---|---|---|---|
| LV end-diastolic diameter (mm) | 49 ± 8 | 49 ± 7 | 47 ± 7 | .25 | .08 |
| LV end-systolic diameter (mm) | 34 ± 10 | 33 ± 9 | 31 ± 8 | .39 | .02 |
| Left ventricular mass (g) | 259 ± 90 | 255 ± 79 | 232 ± 68 | .57 | .05 |
| LV EF (%) | 49 ± 13 | 50 ± 12 | 53 ± 11 | .17 | .006 |
| Mean transaortic gradient (mm Hg) | 50 ± 17 | 11 ± 4 | 10 ± 4 | <.0001 | <.0001 |
| Aortic valve area (cm 2 ) | 0.69 ± 0.17 | 1.77 ± 0.41 | 1.78 ± 0.45 | <.0001 | <.0001 |
| Aortic regurgitation grade after TAVI | — | 0.9 ± 0.6 | 1.0 ± 0.6 | .51 | |
| Left atrial area (cm 2 ) | 27 ± 8 | 26 ± 8 | 26 ± 8 | .57 | .17 |
| E/A ratio | 1.17 ± 0.90 | 1.05 ± 0.63 | 0.86 ± 0.31 | .26 | .07 |
| Systolic pulmonary artery pressure (mm Hg) | 48 ± 14 | 43 ± 12 | 44 ± 11 | .0001 | .008 |
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