Author + information
- Received December 15, 2015
- Revision received February 3, 2016
- Accepted February 26, 2016
- Published online August 1, 2016.
- Yigal Abramowitz, MD,
- Yoshio Maeno, MD, PhD,
- Tarun Chakravarty, MD,
- Yoshio Kazuno, MD,
- Nobuyuki Takahashi, MD,
- Hiroyuki Kawamori, MD, PhD,
- Geeteshwar Mangat, MD,
- Wen Cheng, MD,
- Hasan Jilaihawi, MD and
- Raj R. Makkar, MD∗ ()
- ↵∗Reprint requests and correspondence:
Dr. Raj R. Makkar, Cedars-Sinai Heart Institute, 127 South San Vicente Boulevard, AHSP, Suite A3600, Los Angeles, California 90048.
Objectives The aim of this study was to evaluate the impact of increased aortic angulation (AA) on acute procedural success following transcatheter aortic valve replacement (TAVR).
Background The degree of angulation between the aorta and the heart can make accurate positioning of the bioprosthesis during TAVR more demanding, particularly in instances of an extremely angulated or horizontal aortic root. Nonetheless, there are limited data on the impact of AA on the acute success of TAVR.
Methods We assessed 582 patients who underwent TAVR at our institute and had contrast computed tomography available for AA evaluation. TAVR endpoints, device success, and adverse events were considered according to the Valve Academic Research Consortium-2 definitions.
Results The mean angulation of the aorta was 47.3 ± 8.7°. Patients were therefore divided into 2 groups: AA <48° and AA ≥48°. AA in the 480 patients who underwent balloon-expandable (BE) TAVR did not influence acute procedural success or short-term clinical outcome. In contrast, increased AA among the 102 patients who underwent self-expandable (SE) TAVR was found to significantly attenuate procedural success (area under the curve: 0.73; 95% confidence interval: 0.61 to 0.85; p = 0.008). The numerical cutoff for AA with the highest sum of sensitivity and specificity for device success was ≥48° (sensitivity 85%, specificity 61%). Moreover, patients whose AA was ≥48° were also associated with an increased need for a second valve and post-dilation, had increased fluoroscopy time and increased valve embolization, and had increased post-procedural paravalvular regurgitation greater than or equal to mild following SE TAVR. Major complications at 30 days, including mortality were similar between AA groups. Six-month mortality was also similar between both AA groups.
Conclusions Increased aortic root angulation adversely influences acute procedural success following SE but not BE TAVR. Because of these data, BE valves may be preferred when evaluating patients with high AA before TAVR.
Transcatheter aortic valve replacement (TAVR) has emerged as a treatment option for inoperable or high-risk surgical patients with severe aortic valve disease (1,2). The horizontal aorta poses significant anatomic and technical challenges to successful positioning and optimal deployment of the bioprosthetic valve during TAVR (3–5). Patients with aortic angulation (AA) >70° are usually excluded from clinical trials of self-expandable (SE) TAVR (6). Nonetheless, there are limited data on the impact of AA on the acute success of TAVR. A previous report found an association between increased AA diagnosed angiographically and increased post-procedural paravalvular regurgitation (PVR) among 50 patients who underwent SE TAVR (7). Evaluation of the aortic valve complex and the ascending aorta with computed tomography (CT) provides useful information for treatment planning because it enables evaluation of aortic valve calcification, assessment of the takeoff of the ascending aorta, and accurate measurement of the aortic annulus (4,8).
The purpose of the present study was to evaluate the impact of increased AA on acute procedural success following TAVR.
We retrospectively examined 582 patients with severe symptomatic aortic stenosis who underwent TAVR at our institute and had contrast CT available for AA evaluation. All patients had congestive heart failure with New York Heart Association functional class II to IV symptoms. All underwent pre-procedural coronary angiography to assess the need for revascularization. Aortic valve disease was assessed with transthoracic echocardiography performed by experienced echocardiographers. Evaluation of aortic stenosis severity was performed based on peak velocity, mean gradient, and calculation of the aortic valve area (AVA) using the continuity equation as recommended by current guidelines. All patients had an AVA of <1 cm2 and an indexed AVA (AVA/body surface area) of <0.6 cm2/m2. Patients were also evaluated by an electrocardiographically gated, multislice CT angiography study with a Siemens Somatom Cardiac 64 scanner or a Siemens Somatom Flash scanner (Siemens Medical Solutions USA Inc., Malvern, Pennsylvania). Angulation of the aorta was calculated from a coronal projection at the level of the aortic annulus (Figure 1). AA was defined as the angle between the horizontal plane and the plane of the aortic annulus. The measurement of AA was performed blinded to the implanted valve type. The mean AA was 47.3 ± 8.7°. Patients were therefore divided into 2 groups: AA <48° and AA ≥48°. From a repeated measurement for a subset of 20 randomly selected patients, intraobserver and interobserver variability for AA was satisfactory (intra-observer: intraclass correlation coefficient: 0.95; p < 0.001; interobserver: intraclass correlation coefficient: 0.93; p < 0.001). Aortic valve calcium was quantified by a standard Agatston methodology for all available noncontrast CT scans, with a threshold for calcium detection set at 130 HU and 3-mm slice thickness (9).
Prosthetic valve size selection was based on CT or immediate pre-procedural 3-dimensional transesophageal echocardiography. The vascular access approach was chosen on the basis of the individual patient’s risk profile. Stiff guidewires used during the procedure included the Amplatz extra stiff wire in cases of balloon-expandable (BE) valves (Cook Medical, Bloomington, Indiana) and either the Amplatz super stiff (Boston Scientific, Marlborough, Massachusetts), Confida (Medtronic, Minneapolis, Minnesota), or Lunderquist extra stiff (Cook Medical) in cases of SE valves. All patients were considered high risk for valve surgery by our institutional heart team. Baseline clinical, echocardiographic, and procedural details for TAVR were recorded for all patients, including 1 month clinical and echocardiographic assessments during a follow-up visit. TAVR endpoints, device success, and adverse events were considered according to the Valve Academic Research Consortium-2 definitions (10). Post-TAVR PVR was assessed in line with Valve Academic Research Consortium-2 criteria with peri-procedural transesophageal echocardiography examinations reviewed retrospectively. This was performed by one of the physician readers experienced in the assessment of TAVR echocardiograms, blinded to the clinical data. The study was approved by the institutional review board, and informed consent was obtained from all subjects.
All data were summarized and displayed as mean ± SD for continuous variables and as number (percentage) of patients in each group for categorical variables. The Student t test and the Pearson chi-square test or Fisher exact test were used to evaluate statistical significance between continuous and categorical variables, respectively. For each acute procedural success outcome variable that was found to be significantly associated with AA in a univariable model, we performed a logistic regression analysis, including baseline variables that were found to be different between the AA groups with a p value of <0.1. Receiver-operating characteristic (ROC) curves were generated using device success as the event. A cutoff of AA was examined using the area under the curve (AUC) on the basis of the highest sum of the sensitivity and specificity for the prediction of device success. All of the analyses were considered significant at a 2-tailed p value of <0.05. The SPSS statistical package version 20.0 (IBM, Armonk, New York) was used to perform all statistical evaluations.
Overall, 677 patients underwent CoreValve (Medtronic) or Sapien/Sapien XT/Sapien 3 (Edwards Lifesciences, Irvine, California) TAVR at our institute during the study period. Ninety-five patients who did not have concurrent contrast CT scans available for analysis of AA were excluded. Of the remaining 582 patients, 299 patients had AA <48° (AA: 40.6 ± 5.1°), and 283 had AA ≥48° (AA: 54.4 ± 5.2°). The baseline clinical patient characteristics and pre-TAVR imaging details of the study population are shown in Table 1. Body mass index was significantly higher among patients with AA ≥48° (27.6 ± 5.9 kg/m2 vs. 26.2 ± 5.2 kg/m2; p = 0.003). All other baseline clinical, echocardiographic, and CT variables were similar between both groups (Table 1).
Procedural details for patients who underwent BE and SE TAVR are shown in Table 2. Overall, the transfemoral approach was used in 87.2% of the cases, transapical approach in 3.1%, transaortic approach in 8.7%, and the subclavian approach in 1.0%. BE TAVR was performed in 480 patients and SE TAVR in 102 patients. For BE TAVR, there was no significant difference in valve type, valve sizes, device success, post-procedural PVR, and 30-day complications, including mortality between both AA groups (Tables 2 and 3, Figure 2). Device success remained nonsignificantly different between groups after excluding the 73 patients who underwent an alternative access (Table 3). In patients who had SE TAVR, acute procedural success was lower among patients with increased AA. Device success was significantly lower in the AA ≥48° group (76.1% vs. 96.4%; p = 0.002). In a multivariable model, including baseline and procedural variables that were different between AA groups (body mass index and bioprosthetic valve size), device success remained significantly lower in the higher AA group (odds ratio [OR]: 0.15; 95% confidence interval [CI]: 0.03 to 0.78; p = 0.02) (Table 3). AA was evaluated with ROC curve analysis for its predictive value of device success in the 102 patients who underwent SE TAVR. AA as a continuous variable was found to predict device success (AUC: 0.73; 95% CI: 0.61 to 0.85; p = 0.008) (Figure 3). The numerical cutoff for AA with the highest sum of sensitivity and specificity for device success was ≥48° (sensitivity 85%, specificity 61%). Need for post-dilation was significantly higher in the group with AA ≥48° (47.8% vs. 14.3%; p < 0.001). Post-procedural rates of PVR greater than or equal to mild were significantly higher with increased AA (PVR greater than or equal to mild: 63% vs. 34% in the high and low AA groups, respectively; p = 0.02). In the multivariable model, it remained an independent predictor of higher PVR rates (OR for PVR greater than or equal to mild: 2.76; 95% CI: 1.15 to 6.6; p = 0.02). All 4 cases of SE valve embolization were in patients with AA ≥48° (p = 0.04). These 4 cases included implantation of 2 cases of 31-mm valves, 1 case of a 29-mm valve, and 1 case of a 26-mm valve. The range of AA in these cases was 50° to 57°. In 2 of these cases, the valve moved up into the ascending aorta following complete deployment, and in 2 cases, a partially deployed valve was ejected into the left ventricular outflow tract or to the ascending aorta and could not be retrieved, and therefore, was deployed in the descending aorta. Major complications at 30 days, including mortality, were similar between the AA groups. Six-month mortality was also similar between both AA groups (Table 2).
Horizontal aorta, the extreme form of increased aortic root angulation, can set significant challenges while performing TAVR (3–5,11,12). Nonetheless, the effect of increased AA on acute procedural success following TAVR was not previously examined systematically. In the present study, we found the mean aortic root angulation to be 47.3 ± 8.7°. We divided the patients into high (≥48°) and low (<48°) AA groups and assessed the influence of AA on acute device success following TAVR. In patients who underwent BE TAVR (n = 480), we found similar high device success and low PVR rates in both AA groups. In contrast, in patients who underwent SE TAVR (n = 102), we found an inverse ratio between increased aortic root angulation and acute procedural success. Higher AA was associated with lower device success rates, higher post-procedural PVR rates, a higher need for post-dilation or a second valve, and a higher incidence of valve embolization following SE TAVR.
The degree of angulation between the aorta and the heart can make accurate positioning of the bioprosthesis during TAVR more demanding, particularly in instances of a horizontal aortic root with a vertical aortic annulus (4,5). Moreover, an angle between the plane of the aortic valve annulus and horizontal plane/vertebrae of >70° is an exclusion criteria for clinical trials with SE valves (6). A few case reports have described the challenges posed by an extremely angulated aorta during SE TAVR and have suggested measures, such as the buddy balloon technique, to overcome the difficulties to accurately position the bioprosthetic valve (3,11,12). The transapical or direct aortic approach using mini-thoracotomy may be reasonable alternatives in such challenging cases (3,13).
There are limited data regarding the effect of the range of AA on acute device success following TAVR. In the present study, we found that aortic root angulation did not influence the short-term clinical outcome following BE TAVR. All measures of short-term procedural success, including device success, need for a second valve or post-dilation, PVR rates, major complications, and mortality were similar between the 2 AA groups (Table 2, Figure 2). The relatively short valve stent frame and the flexibility of the delivery system were the main factors that contributed to these results.
Interestingly, we demonstrated an independent significant correlation between increased AA and reduced device success in patients who underwent SE TAVR. ROC curve analysis showed the best cutoff for prediction of decreased device success to be similar to the cutoff we chose based on mean AA (between 47° and 48°). Several measures of procedural success were significantly different in the increased AA group: lower device success (76.1% vs. 96.4%); increased need for a second valve and post-dilation; increased fluoroscopy time; increased valve embolization rates; and increased PVR greater than or equal to mild (Table 2, Figure 2). It should be noted that these differences did not result in a significant increase in short-term mortality or complications following SE TAVR.
Only one previous study examined the effect of aortic root angulation on the outcome following TAVR. Sherif et al. (7) evaluated 50 patients who underwent SE CoreValve TAVR. They assessed AA using left ventriculography in a right anterior oblique projection of 30° during preparation of the patients for the procedure. They found a greater chance of significant PVR with a greater AA. The main limitations of this study were the relatively small number of patients, the evaluation of only SE valves, and the method of AA assessment, which did not include CT, which is considered a more accurate modality to assess the aortic valve and aortic root before TAVR (4).
Possible reasons for the difference in outcomes in patients with higher AA following SE but not BE valve implantations are illustrated in Figure 4. In cases of SE valves, the longer valve stent frame (49 to 52 mm) in the presence of a more angulated aorta may result in less accurate and less symmetrical positioning of the valve, adversely affecting acute procedural success. Moreover, stent deformation, which is also influenced by the stiffness of the aorta and the calcific nature of the aortic root and valve, may affect the radial force of the prosthesis and its ability to completely seal the paravalvular space (7). In cases of the shorter stent frame of BE valves (14.0 to 22.5 mm), there is less interaction with the aorta, and the frame apposition is localized primarily to the aortic annulus, thus minimizing the previously mentioned adverse effects. Moreover, the delivery system of BE valves (Edwards Novaflex or Commander) enables active flexion and extension during valve advancement, a feature that helps the operator to optimize coaxial alignment of the prosthesis when faced with challenging aortic anatomy.
In cases of extreme AA, using a buddy balloon technique may ease the advancement of the undeployed valve into the annulus (11). In extreme AA cases of SE implantations, it may be useful to mount a snare catheter onto the delivery system and advance both together (12). This technique allows the snare catheter to be placed anywhere along the delivery system for applying traction as it navigates through the aortic arch and root. The operator can apply a constant flexion force on the delivery system through the proximal end of the snare catheter, thereby aligning it toward the center of the annulus.
In SE TAVR, the Lundequist guidewire has increased stiffness compared with both the Amplatz supra stiff and Confida guidewires, and the operator may choose a stiffer wire when faced with an increased AA to have better control while advancing the valve. Newer generation repositionable SE valves may be more efficient in cases of extreme angulation of the aorta.
The main limitations of the present study are that it represents a retrospective, single-center experience. The higher volume of BE valve implantations compared with SE valve implantation may also have influenced the results. Moreover, only 13% of the patients had alternative access TAVR in the present cohort, and therefore, the suggested cutoff of AA is valid mostly for patients who had transfemoral access TAVR. Future studies with a larger number of patients, longer follow-up, and use of different valve types, including re-positional SE devices may further clarify this subject. A randomized trial with both BE or SE valves for patients with increased AA may also better evaluate the effect of aortic root angulation on the clinical outcome following TAVR.
Increased aortic root angulation adversely influences acute procedural success following SE but not BE TAVR. Because of these data, BE valves might be preferred when evaluating patients with high AA before TAVR.
COMPETENCY IN PATIENT CARE AND PROCEDURAL SKILLS: Patients with increased aortic angulation who undergo TAVR represent a challenging subset of patients in whom the rates of procedural success and occurrence of post-procedural PVR may be higher with the use of self-expandable valves.
TRANSLATIONAL OUTLOOK: Future studies with new-generation valves should address aortic angulation evaluation and its relation to both short- and long-term clinical outcome following TAVR.
This study was funded by the Cedars-Sinai Heart Institute. Dr. Jilaihawi is a consultant for Edwards Lifesciences Corporation, St. Jude Medical, and Venus MedTech. Dr. Makkar has received grant support from Edwards Lifesciences Corporation and St. Jude Medical; is a consultant for Abbott Vascular, Cordis, and Medtronic; and holds equity in Entourage Medical. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.
- Abbreviations and Acronyms
- aortic angulation
- area under the curve
- aortic valve area
- confidence interval
- computed tomography
- odds ratio
- paravalvular regurgitation
- receiver-operating characteristic
- transcatheter aortic valve replacement
- Received December 15, 2015.
- Revision received February 3, 2016.
- Accepted February 26, 2016.
- American College of Cardiology Foundation
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