Abstract
Background
Balloon valvuloplasty has been considered a mandatory step of the transcatheter aortic valve implantation (TAVI), although it is not without risk. The aim of this work was to evaluate the feasibility and safety of TAVI performed without pre-dilation (direct TAVI) of the stenosed aortic valve.
Material and Methods
Between June 2012 and June 2013, 55 consecutive TAVI performed without pre-dilation at our institution using the self-expandable CoreValve prosthesis (Medtronic, Minneapolis, MN) were analyzed and compared with 45 pre-dilated TAVI performed the previous year. Inclusion criteria were a symptomatic and severe aortic stenosis. Exclusion criteria were defined as presence of pure aortic regurgitation, degenerated surgical bioprosthesis or bicuspid aortic valve and prior procedure of balloon aortic valvuloplasty performed as a bridge to TAVI.
Results
High-burden calcification in the device landing zone, assessed by CT scan, was found in most of the patients. The valve size implanted was similar in both groups. Device success was higher in direct TAVI (85% vs. 64%, p = 0.014), mostly driven by a significant lower incidence of paravalvular leak (PVL ≥2; 9% vs. 33%, p = 0.02). Safety combined end point at 30 days was similar in both groups.
Conclusion
Compared to TAVI with pre-dilation, direct TAVI is feasible regardless of the presence of bulky calcified aortic valve and the valve size implanted. Device success was higher in direct TAVI, mostly driven by a lower incidence of paravalvular leak. Safety at 30 days was similar in two groups.
1
Introduction
Transcatheter aortic valve implantation (TAVI) has gained rapid momentum increasing the number of procedures performed using both balloon-expandable and self-expandable prosthesis. Today there is strong evidence that this technology is highly effective in patients with symptomatic severe aortic stenosis and high surgical risk . From the very beginning of TAVI technology, valve preparation with balloon valvuloplasty before the device placement has been considered a mandatory step in a TAVI procedure to facilitate the implantation of the prosthesis and to reduce the radial counter-force to ensure optimal device expansion. However, balloon valvuloplasty carries specific complications and can be held solely responsible for distal embolization resulting in strokes, conduction disturbances and severe aortic regurgitation with hemodynamic relevance. Recent publication by Grube et al. demonstrated the feasibility of performing TAVI with self-expandable valve without balloon pre-dilation (direct TAVI), with a technical success rate of 96.7%. The purposes of this study were 1) to assess the feasibility of consecutive direct TAVI compared to an historical control group undergoing pre-dilation; 2) to address the role of the amount of calcium on native valve cusps and the valve size on device success in direct TAVI compared to the control group; and 3) to compare the safety at 30-day follow-up in both groups.
2
Methods
2.1
Population
Between June 2012 and June 2013, we prospectively included all consecutive patients undergoing TAVI using the self-expanding 18-F Medtronic CoreValve prosthesis (Medtronic, Minneapolis, MN) at our institution. Clinical, electrocardiographic and echocardiographic evaluation was performed at baseline and after the procedure, at hospital discharge and at 30-day follow-up. All patients underwent pre-procedural computed tomography (CT) screening, which was also used to quantify valve calcification and its distribution on the three valve cusps. The total amount of calcification in the device landing zone (DLZ) was assessed by a semi-quantitative estimation on the basis of the DLZ calcification score (DLZ-CS): grade 1 = mild calcification, 2 = moderate calcification, 3 = heavy calcification (mostly associated with commissural fusion), and 4 = massive calcification including large calcification clumps out-reaching the annulus level . Patient inclusion criteria have been described elsewhere . Exclusion criteria for direct TAVI were: pure aortic regurgitation, degenerated surgical bioprosthesis, bicuspid aortic valve, previous procedure of balloon aortic valvuloplasty performed as a bridge to TAVI and pre-dilation performed to exclude coronary occlusion. All patients provided written informed consent before the procedure.
2.2
Procedure and definition
Design characteristics of CoreValve prosthesis as well as the procedural characteristics have been described elsewhere . The vascular access (trans-femoral, trans-subclavian, trans-aortic route) was chosen on the basis of CT scan analysis. Since June 2012, the direct TAVI technique has became a routine procedure in our cath lab. We retrospectively compared the results with pre-dilated TAVI performed the previous year. CT scan data regarding the grade of aortic valve calcification were analyzed by two independent experts operators (E.G., D.M.). After placing a manually shaped, stiff guide wire in the ventricle and replacing the pigtail catheter, the prosthesis was advanced over the aortic arch or directly through the ascending aorta (in case of trans-aortic approach) and placed within the diseased native valve. Inability to advance the prosthesis up to the final position within the native valve was considered a device failure. The prosthesis was then implanted within the native valve followed by repeated invasive hemodynamic gradient measurement as well as angiographic assessment of paravalvular regurgitation. In case of significant paravalvular leak (≥ 2 +), post-dilation, implantation of a second device or conversion to surgery was considered. The assessment of aortic regurgitation severity was evaluated by an aortographic contrast injection after device deployment using a scale of 1 + to 4 + and by the recent quantified index of aorta regurgitation severity (AR index) . Feasibility was assessed by the device success, defined according to Valve Academic Research Consortium-2 (VARC-2) criteria . Particularly, in direct TAVI group we evaluated the ability to cross the native aortic valve without balloon pre-dilation with a final correct position of the device in the proper anatomical location with a good performance of the prosthesis (aortic valve area > 1.2 cm 2 and a mean aortic valve gradient < 20 mm Hg, without moderate or severe paravalvular regurgitation). Patients were followed by clinical and echocardiographic assesment at 1-, 6-, and 12-month follow-ups. Clinical events were defined on the basis of the VARC-2 definitions .
2.3
Statistical analysis
Continuous variables were expressed as mean ± standard deviation and categorical variables were presented as counts and percentage. Group comparisons were analyzed using the Student t test for continuous variables, and chi-square test or Fisher test for categorical variables. The results were considered significant with a p values < 0.05. All analyses were performed using SPSS version 12 statistical software (SPSS Inc., Chicago, IL).
2
Methods
2.1
Population
Between June 2012 and June 2013, we prospectively included all consecutive patients undergoing TAVI using the self-expanding 18-F Medtronic CoreValve prosthesis (Medtronic, Minneapolis, MN) at our institution. Clinical, electrocardiographic and echocardiographic evaluation was performed at baseline and after the procedure, at hospital discharge and at 30-day follow-up. All patients underwent pre-procedural computed tomography (CT) screening, which was also used to quantify valve calcification and its distribution on the three valve cusps. The total amount of calcification in the device landing zone (DLZ) was assessed by a semi-quantitative estimation on the basis of the DLZ calcification score (DLZ-CS): grade 1 = mild calcification, 2 = moderate calcification, 3 = heavy calcification (mostly associated with commissural fusion), and 4 = massive calcification including large calcification clumps out-reaching the annulus level . Patient inclusion criteria have been described elsewhere . Exclusion criteria for direct TAVI were: pure aortic regurgitation, degenerated surgical bioprosthesis, bicuspid aortic valve, previous procedure of balloon aortic valvuloplasty performed as a bridge to TAVI and pre-dilation performed to exclude coronary occlusion. All patients provided written informed consent before the procedure.
2.2
Procedure and definition
Design characteristics of CoreValve prosthesis as well as the procedural characteristics have been described elsewhere . The vascular access (trans-femoral, trans-subclavian, trans-aortic route) was chosen on the basis of CT scan analysis. Since June 2012, the direct TAVI technique has became a routine procedure in our cath lab. We retrospectively compared the results with pre-dilated TAVI performed the previous year. CT scan data regarding the grade of aortic valve calcification were analyzed by two independent experts operators (E.G., D.M.). After placing a manually shaped, stiff guide wire in the ventricle and replacing the pigtail catheter, the prosthesis was advanced over the aortic arch or directly through the ascending aorta (in case of trans-aortic approach) and placed within the diseased native valve. Inability to advance the prosthesis up to the final position within the native valve was considered a device failure. The prosthesis was then implanted within the native valve followed by repeated invasive hemodynamic gradient measurement as well as angiographic assessment of paravalvular regurgitation. In case of significant paravalvular leak (≥ 2 +), post-dilation, implantation of a second device or conversion to surgery was considered. The assessment of aortic regurgitation severity was evaluated by an aortographic contrast injection after device deployment using a scale of 1 + to 4 + and by the recent quantified index of aorta regurgitation severity (AR index) . Feasibility was assessed by the device success, defined according to Valve Academic Research Consortium-2 (VARC-2) criteria . Particularly, in direct TAVI group we evaluated the ability to cross the native aortic valve without balloon pre-dilation with a final correct position of the device in the proper anatomical location with a good performance of the prosthesis (aortic valve area > 1.2 cm 2 and a mean aortic valve gradient < 20 mm Hg, without moderate or severe paravalvular regurgitation). Patients were followed by clinical and echocardiographic assesment at 1-, 6-, and 12-month follow-ups. Clinical events were defined on the basis of the VARC-2 definitions .
2.3
Statistical analysis
Continuous variables were expressed as mean ± standard deviation and categorical variables were presented as counts and percentage. Group comparisons were analyzed using the Student t test for continuous variables, and chi-square test or Fisher test for categorical variables. The results were considered significant with a p values < 0.05. All analyses were performed using SPSS version 12 statistical software (SPSS Inc., Chicago, IL).
3
Results
Between June 2012 and June 2013, 70 consecutive TAVI were performed at our institution using the self-expandable 18-F Medtronic CoreValve prosthesis. Fifteen patients (21%) were not included in the study according to the exclusion criteria (pure aortic regurgitation, n = 2; degenerated surgical bioprosthesis, n = 3; bicuspid aortic valve, n = 3; previous procedure of balloon aortic valvuloplasty performed as a bridge to TAVI, n = 5; pre-dilation performed to exclude the risk of coronary occlusion, n = 2). Fifty-five consecutive TAVI performed without pre-dilation (direct TAVI, 79%) were analyzed and compared with Forty-five pre-dilation TAVI performed between June 2011 and May 2012. Table 1 shows the baseline characteristics. Mean age and sex female were similar in both groups. The clinical risk profile was higher in direct TAVI compared to the pre-dilated group, particularly regarding STS score. No significant differences were observed in terms of aortic valve area, mean gradient and left ventricular function. Most of the calcifications in the DLZ were of grade 3 and 4 (heavy and massive calcifications) in both groups ( p = 0.8). The distribution of the calcifications on the native cusps of the valve was often asymmetric. The balloon for pre-dilation was undersized (mean balloon/annulus ratio of 0.8 ± 0.07). Device success was higher in direct TAVI compared to the control group (85% vs 64%, respectively, p = 0.014), mostly driven by a significant lower incidence of moderate to severe paravalvular leak post-implantation (PVL ≥ 2; 9% vs 33%, respectively, p = 0.02) as shown in Table 2 . Particularly, in the pre-dilated group, the bigger the valve size implanted, the higher the incidence of significant paravalvular leak. In direct TAVI this relationship was not observed as shown in Fig. 1 . Similarly, paravalvular leak post direct TAVI was not correlated with the high degree of calcification in the DLZ ( Fig. 2 ). However, no significant difference was observed between the two groups in terms of hemodynamic evaluation by aortic regurgitation index (33 ± 8 vs 31 ± 8, respectively, p = 0.26). In direct TAVI, the rate of post-dilation was reduced, although it was not statistically significant (34% vs 51%, respectively, p = 0.09), while the rate of second valve implanted was similar (3.6% vs 4%, respectively, p = 0.8). In the direct TAVI group, 3 of 55 (5%) cases are to be taken in account. A severe paravalvular leak due to an incomplete expansion of the prosthesis deployment at the level of the DLZ was observed in one case. In this individual, a device migration in a higher position (valsalva sinus) occurred during the post-dilation and a second valve implantation was required. Inability to advance the prosthesis up to the final position within the native valve was observed in another patient and a pre-dilation was needed. Finally, the third case had a severe hypotension with cardiac arrest during the placement of bioprosthesis within the native valve. A rapid deployment of the device resulted in immediate recovery. A good performance of prosthesis was observed in both groups with a similar final effective orifice area ( Table 2 ). There was no valve embolization in either group. The rate of new PM implantation after TAVI was reduced in the study group, although it was not statistically significant (5.5% vs 15.5%, respectively, p = 0.09). Follow-up at 30 days was available for all patients (100%) in both groups. Safety combined endpoint at 30 days was similar (14% vs 11%, respectively, p = 0.6) without any significant difference in the individual component of the end point ( Table 3 ).
| Direct TAVI ( n = 55) | Pre-dilated TAVI ( n = 45) | p -Value | |
|---|---|---|---|
| Age (years) | 83 ± 7 | 83 ± 8 | 0.8 |
| Sex, female, n (%) | 28 (51) | 20 (44) | 0.5 |
| Log Euroscore (%) | 27 ± 18 | 22 ± 14 | 0.12 |
| STS score (%) | 10 ± 8 | 7 ± 4 | 0.03 |
| Diabetes mellitus, n (%) | 20 (36) | 10 (22) | 0.12 |
| Hypertension, n (%) | 44 (80) | 31 (69) | 0.2 |
| Prior MI, n (%) | 11 (20) | 3 (6) | 0.05 |
| CAD, n (%) | 26 (47) | 19 (42) | 0.2 |
| Prior PCI, n (%) | 14 (25) | 8 (17) | 0.35 |
| Prior CABG, n (%) | 6 (11) | 6 (13) | 0.7 |
| Porcelain aorta | 6 (10) | 7 (15) | 0.49 |
| Clearance creatinine (ml/min) | 44 ± 23 | 50 ± 24 | 0.35 |
| AVAi (cmq/mq) | 0.39 ± 0.1 | 0.36 ± 0.1 | 0.09 |
| Peak gradient (mm Hg) | 75 ± 21 | 81 ± 26 | 0.2 |
| Mean gradient (mm Hg) | 44 ± 13 | 48 ± 16 | 0.15 |
| LVEF (%) | 49 ± 13 | 46 ± 17 | 0.27 |
| DLZ-CS | |||
| Grades 1–2 | 10 (18) | 9 (20) | 0.8 |
| Grades 3–4 | 45 (82) | 36 (80) | |
| Distribution of the calcification | |||
| Symmetric | 21 (38) | 18 (40) | 0.8 |
| Asymmetric | 34 (62) | 27 (60) | |
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