Prosthesis oversizing in balloon-expandable transcatheter aortic valve implantation is associated with contained rupture of the aortic root

CT-angiography-based evaluation of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI)-predictive value and optimal thresholds for major anatomic parameters

BACKGROUND/OBJECTIVES

To evaluate the predictive value of CT-derived measurements of the aortic annulus for prosthesis sizing in transcatheter aortic valve implantation (TAVI) and to calculate optimal cutoff values for the selection of various prosthesis sizes.

METHODS

The local IRB waived approval for this single-center retrospective analysis. Of 441 consecutive TAVI-patients, 90 were excluded (death within 30 days: 13; more than mild aortic regurgitation: 10; other reasons: 67). In the remaining 351 patients, the CoreValve (Medtronic) and the Edwards Sapien XT valve (Edwards Lifesciences) were implanted in 235 and 116 patients. Optimal prosthesis size was determined during TAVI by inflation of a balloon catheter at the aortic annulus. All patients had undergone CT-angiography of the heart or body trunk prior to TAVI. Using these datasets, the diameter of the long and short axis as well as the circumference and the area of the aortic annulus were measured. Multi-Class Receiver-Operator-Curve analyses were used to determine the predictive value of all variables and to define optimal cutoff-values.

RESULTS

Differences between patients who underwent implantation of the small, medium or large prosthesis were significant for all except the large vs. medium CoreValve (all p's<0.05). Furthermore, mean diameter, annulus area and circumference had equally high predictive value for prosthesis size for both manufacturers (multi-class AUC's: 0.80, 0.88, 0.91, 0.88, 0.88, 0.89). Using the calculated optimal cutoff-values, prosthesis size is predicted correctly in 85% of cases.

CONCLUSION

CT-based aortic root measurements permit excellent prediction of the prosthesis size considered optimal during TAVI.

Open issues in transcatheter aortic valve implantation. Part 1: patient selection and treatment strategy for transcatheter aortic valve implantation

An exponential increase in the use of transcatheter aortic valve implantation (TAVI) in patients with severe aortic stenosis has been witnessed over the recent years. The current article reviews different areas of uncertainty related to patient selection. The use and limitations of risk scores are addressed, followed by an extensive discussion on the value of three-dimensional imaging for prosthesis sizing and the assessment of complex valve anatomy such as degenerated bicuspid valves. The uncertainty about valvular stenosis severity in patients with a mismatch between the transvalvular gradient and the aortic valve area, and how integrated use of echocardiography and computed tomographic imaging may help, is also addressed. Finally, patients referred for TAVI may have concomitant mitral regurgitation and/or coronary artery disease and the management of these patients is discussed.

Ruptures of the device landing zone in patients undergoing transcatheter aortic valve implantation: an analysis of TAVI Karlsruhe (TAVIK) patients

BACKGROUND

Aortic rupture of the device landing zone is a rare complication of transcatheter aortic valve implantation (TAVI) and it is associated with significant mortality.

METHODS

This study reports on the experience of a single-center in a case series of more than 1,000 implants. We explored patient and procedural characteristics aiming at identifying variables that increase the risk for aortic root rupture.

RESULTS

Among a total of 1,000 TAVI procedures, six patients (0.6 %) had a rupture of the device landing zone. Five of these patients received the balloon-expandable Edwards SAPIEN valve (5/813; 0.62 %) of which four had a supraannular and one a subannular rupture. One patient received the self-expanding Medtronic CoreValve (1/199; 0.5 %; p = n.s. vs. SAPIEN) and had an annular rupture. Factors that were associated with aortic rupture were: (1) the relative size of the valve compared with the aortic annulus and its geometric form; (2) the need for post-dilation of the new valve because of paravalvular leakage; and (3) the location and severity of calcification. We determined, to avoid aortic rupture, caution may be necessary in the presence of the following conditions: (1) flat sinuses of Valsalva and severe calcifications of either the body or the free edge of the aortic cusps (supraannular rupture); (2) an ellipsoid annulus and bulky calcifications on either the base of the cusps or the rim of the annulus (annular rupture); and (3) a narrow left-ventricular outflow tract (LVOT) and bulky calcification of the LVOT (subannular rupture). After considering these precautions, we observed no case of aortic root rupture in the following 600 cases.

CONCLUSION

The data indicate that to reduce the frequency of aortic rupture, a careful pre-procedural planning appears essential to avoid this serious and potentially deleterious complication.

Reproducibility of aortic annulus measurements by computed tomography

OBJECTIVES

To evaluate a systematic approach for measurement of aortic annulus dimensions by cardiac computed tomography.

METHODS

CT data sets of 64 patients were evaluated. An oblique cross-section aligned with the aortic root was created by systematically identifying the caudal insertion points of the three aortic cusps and sequentially aligning them in a double oblique plane. Aortic annulus dimensions, distances of coronary ostia and a suitable fluoroscopic projection angle were independently determined by two observers.

RESULTS

Interobserver intraclass correlation coefficients (ICC) for aortic annulus diameters were excellent (ICC 0.89-0.93). Agreement for prosthesis size selection was excellent (ĸ = 0.86 for mean, ĸ = 0.84 for area-derived and ĸ = 0.91 for circumference-derived diameter). Mean distances of the left/right coronary ostium were 13.4 ± 2.4/14.4 ± 2.8 mm for observer 1 and 13.2 ± 2.7/13.5 ± 3.2 mm for observer 2 (p = 0.30 and p = 0.0001, respectively; ICC 0.76/0.77 for left/right coronary artery). A difference of less than 10° for fluoroscopic projection angle was achieved in 84.3% of patients.

CONCLUSIONS

A systematic approach to generate a double oblique imaging plane exactly aligned with the aortic annulus demonstrates high interobserver and intraobserver agreements for derived measurements which are not influenced by aortic root calcification.

KEY POINTS

• Systematic approach to generate a double oblique imaging plane for TAVI evaluation. • This method is straightforward and software independent. • An approach with high reproducibility, not influenced by aortic root calcification.

Transcatheter aortic valve implantation in patients of small body size

AIMS

The aim of this study was to evaluate the efficacy and safety of transcatheter aortic valve implantation (TAVI) in patients of small body size (SB).

METHODS AND RESULTS

Between October 2006 and November 2011, 424 patients undergoing TAVI were evaluated. Patients with a small body surface area (BSA; <1.75 m(2)) were defined as the "SB group" (n = 215) and the remaining large BSA patients as the "LB group" (n = 209). In the SB group, mean annulus diameter measured by CT and minimal femoral artery diameter were significantly smaller (23.1 ± 1.92 vs. 24.3 ± 1.91 mm, P < 0.01; 7.59 ± 1.06 vs. 8.29 ± 1.34 mm, P < 0.01, respectively). The logistic EuroSCORE was similar between groups (22.5 ± 10.4 vs. 23.4 ± 12.0; P = 0.43). Equivalent device success (91.2% vs. 91.4%; P = 0.94) and 30-day survival rates (85.1% vs. 87.6%; P = 0.46) were achieved in both groups. Vascular complications and the 30-day combined safety end point rate were significantly higher in the SB group (13.0% vs. 4.3%, P < 0.01; 27.4% vs. 18.3%, P = 0.03, respectively). Similar post-procedural mean pressure gradient was achieved in both groups (10.2 ± 4.3 vs. 11.0 ± 4.6 mmHg; P = 0.12). Multivariate analysis showed that BSA was one of the independent predictors of 30-day combined safety end point (Odds ratio: 0.20; 95% confidence interval (CI): 0.05-0.88; P = 0.03). However, Kaplan-Meier analysis revealed no significant difference in mid-term survival rate between groups (log-rank P = 0.64).

CONCLUSIONS

TAVI in SB patients resulted in similar clinical outcomes with effective post-procedural hemodynamics compared with LB patients. Care should be taken to avoid vascular complications in SB patients.

Impact of post-implant SAPIEN XT geometry and position on conduction disturbances, hemodynamic performance, and paravalvular regurgitation

OBJECTIVES

This report sought to study the impact of the balloon-expandable SAPIEN XT (Edwards Lifesciences, Irvine, California) transcatheter heart valve (THV) stent frame geometry and position on outcomes of transcatheter aortic valve replacement (TAVR).

BACKGROUND

Post-implant THV geometry and position might impact atrioventricular conduction, hemodynamic performance, and annular sealing.

METHODS

Eighty-nine consecutive patients who underwent TAVR with a Sapien XT THV had pre- and post-implant multidetector computed tomography, transthoracic echocardiography, and electrocardiograms performed to assess THV stent geometry, atrioventricular conduction, and hemodynamic performance.

RESULTS

The THV Circularity (THV eccentricity <10% [eccentricity = minimum stent diameter/maximum stent diameter]) and under-expansion (THV area/nominal THV area <90%) were present in 97.8% (2 of 89) and 0%, respectively. Low THV implantation was associated with new left bundle branch block and complete heart block (3.4 ± 2.0 mm vs. 5.5 ± 2.9 mm, p = 0.01) and with the need for permanent pacemaker implantation (3.5 ± 2.0 mm vs. 7.1 ± 2.5 mm, p = 0.001). In contrast, labeled THV size and THV area oversizing was not associated with atrioventricular conduction disturbances. The relation between inflow stent frame area and annular area was related to paravalvular regurgitation (p = 0.025). Labeled prosthesis size but not prosthesis expansion or eccentricity was related to valve gradient (p = 0.005) and effective orifice area (p < 0.001).

CONCLUSIONS

Low implantation depth of balloon-expandable THVs is associated with clinically significant new conduction disturbances and permanent pacemaker implantation. Importantly, annular area oversizing was not associated with these complications.

Imaging in Transcatheter Aortic Valve Replacement (TAVR): role of the radiologist

BACKGROUND

Transcatheter aortic valve replacement (TAVR) is a novel technique developed in the last decade to treat severe aortic stenosis in patients who are non-surgical candidates because of multiple comorbidities.

METHODS

Since the technique is performed using a transvascular approach, pre-procedural assessment of the aortic valve apparatus, ascending aorta and vascular access is of paramount importance for both appropriate patient selection and correct device selection. This assessment is performed by a multi-disciplinary team with radiology being an integral and important part.

RESULTS

Among imaging modalities, there is growing scientific evidence supporting the crucial role of MDCT in the assessment of the aortic valve apparatus, suitability of the iliofemoral or alternative pathway, and determination of appropriate coaxial angles. MDCT also plays an important role in post-procedure imaging in the assessment of valve integrity and position.

CONCLUSION

This review outlines the principal aspects of TAVR, the multidisciplinary approach and utilisation of different imaging modalities, as well as a step-by-step approach to MDCT acquisition protocols, reconstruction techniques, pre-procedure measurements and post-procedure assessment.

TEACHING POINTS

• TAVR is a new technique to treat severe aortic stenosis in high-risk and nonsurgical candidates. • MDCT assessment of the aortic annulus is important for appropriate patient and device selection. • Multidisciplinary approach is required for patient selection, procedure planning and performance. • MDCT is required for assessment of the aortic root, iliofemoral or alternative vascular pathway.

Mechanisms and management of TAVR-related complications

Patients with severe aortic stenosis who are at high surgical risk or not considered to be suitable candidates for surgical aortic valve replacement are increasingly being treated with transcatheter aortic valve replacement (TAVR). Although this novel treatment modality has been proven to be effective in this patient population, serious complications occur in approximately one-third of patients during the month after the procedure. Such events include myocardial infarction, cerebrovascular events, vascular complications, bleeding, acute kidney injury, valve regurgitation, valve malpositioning, coronary obstruction, and conduction disturbances and arrhythmias, which can all lead to death. Prevention of these complications should be based on patient screening and selection by a dedicated 'heart team' and the use of multimodality imaging. Anticipation and early recognition of these complications, followed by prompt management using a wide range of percutaneous or surgical rescue interventions, is vital to patient outcome. Continuous patient assessment and reporting of complications according to standardized definitions, in addition to growing operator experience and upcoming technological refinements, will hopefully reduce the future rate of complications related to this procedure.

Standardized imaging for aortic annular sizing: implications for transcatheter valve selection

The safety and efficacy of transcatheter aortic valve replacement procedures are directly related to proper imaging. This report revisits the existing noninvasive and invasive approaches that have concurrently evolved to meet the demands for optimal selection and guidance of patients undergoing transcatheter aortic valve replacement. The authors summarize the published evidence and discuss the strengths and pitfalls of echocardiographic, computed tomographic, and calibrated aortic balloon valvuloplasty techniques in sizing the aortic valve annulus. Specific proposals for 3-dimensional tomographic reconstructions of complex 3-dimensional aortic root anatomy are provided for reducing intermodality variability in annular sizing. Finally, on the basis of the sizing approaches discussed in this review, the authors provide practical recommendations for balloon-expandable and self-expandable prostheses selection. Strategic use of echocardiographic, multislice computed tomographic, and angiographic data may provide complementary information for determining the anatomical suitability, efficacy, and safety of the procedure.

Transfemoral aortic valve implantation in patients with an annulus dimension suitable for either the Edwards valve or the CoreValve

The aim of this study was to compare the outcomes of transcatheter aortic valve implantation using the Edwards SAPIEN valve and the Medtronic CoreValve in patients with annulus of intermediate size (20 to 25 mm). From October 2008 to April 2012, 662 consecutive patients who underwent transcatheter aortic valve implantation were studied at 2 French centers. After propensity score matching, a total of 192 patients with intermediate-sized aortic annulus who had received either Edwards (n = 96, mean age 82.4 ± 7.9 years, 48% men, 61.9% receiving the 26-mm valve) or CoreValve (n = 96, mean age 82.5 ± 7.7 years, 50% men, 64.6% receiving the 29-mm valve) prostheses through the transfemoral approach were studied. Adequate reduction in postprocedural mean pressure gradients was achieved with the Edwards valve and the CoreValve (10.9 ± 4.7 vs 9.1 ± 4.4 mm Hg, respectively, p <0.01). Major vascular complications (5.2% vs 3.1%, p = 0.36), device success (95.8% vs 93.8%, p = 0.52), and 30-day survival (90.6% vs 89.6%, p = 0.81) were similar. The incidence of postprocedural aortic regurgitation grade ≥2/4 and new pacemaker implantation was more frequent in the CoreValve group (14.3% vs 35.5%, p <0.01, and 4.2% vs 18.8%, p <0.01, respectively). There was no significant difference in 1-year cumulative survival rates in the Edwards valve group compared with the CoreValve group (80.1 ± 4.2% vs 75.6 ± 4.9%, log-rank p = 0.31). In conclusion, in patients with annulus of intermediate size, similar device success and short-term and midterm outcomes were achieved with either of the valves, irrespective of the specific complications related to each valve.

An update on complications associated with transcatheter aortic valve implantation: stroke, paravalvular leak, atrioventricular block and perforation

Transcatheter aortic valve implantation (TAVI) has become an alternative therapeutic option for patients with symptomatic severe aortic stenosis at high surgical risk and the standard of care in patients who are inoperable for open aortic valve replacement. With technological evolution and increasing experience, the procedure has become more predictable. Complications of TAVI, however, are not infrequent, and can range from minor to life-threatening events. Stroke, paravalvular leak, various forms of atrioventricular block, including the need for permanent pacemakers and aortic annular and ventricular perforation will be the focus of the present review. Other complications associated with TAVI (such as vascular injury, acute kidney injury, coronary obstruction, valve malpositioning or migration) are clinically important, but are beyond the scope of this article. Understanding the occurrence and pathophysiology of these complications may provide insights into the improvement of the transcatheter devices and techniques, and aid in extending the application of TAVI to a broader population.

Three-dimensional multidetector computed tomography versus conventional 2-dimensional transesophageal echocardiography for annular sizing in transcatheter aortic valve replacement: Influence on postprocedural paravalvular aortic regurgitation

OBJECTIVES

In transcatheter aortic valve replacement (TAVR), the influence of aortic annular assessment with either multidetector computed tomography (MDCT) or conventional transesophageal echocardiography (TEE) on the incidence of postprocedural paravalvular aortic regurgitation (PAR) was evaluated.

BACKGROUND

PAR remains a major limitation in TAVR. Appropriate selection of transcatheter heart valve (THV) size is crucial to prevent PAR.

METHODS

Outcomes following TAVR with a balloon-expandable THV were compared in two retrospective cohorts identified according to whether THV size selection was based on TEE (study group 1, n = 80) or MDCT (study group 2, n = 58).

RESULTS

The two study groups were comparable with regard to baseline clinical, risk score, and echocardiographic characteristics. The incidence of moderate/severe PAR was lower in study group 2 than in group 1, 8.6% versus 28.8% (P < 0.01). The difference between the THV nominal diameter and MDCT annular diameter was predictive of moderate/severe PAR (AUC 0.84; 95% CI: 0.72-0.92). Neither age, gender, body mass index, annular eccentricity index, aortic valve calcification nor the difference between the THV diameter and the TEE annular diameter predicted postprocedural PAR. Increased THV oversizing relative to the MDCT mean annular diameter was associated with reduced severity of PAR. No difference in perprocedural complications between two study groups was observed.

CONCLUSION

MDCT-based annular sizing in TAVR significantly reduces postprocedural PAR, and THV oversizing appears pivotal in this aspect. Further delineation of the optimal degree of THV oversizing is needed.

Anatomical and procedural features associated with aortic root rupture during balloon-expandable transcatheter aortic valve replacement

BACKGROUND

Aortic root rupture is a major concern with balloon-expandable transcatheter aortic valve replacement (TAVR). We sought to identify predictors of aortic root rupture during balloon-expandable TAVR by using multidetector computed tomography.

METHODS AND RESULTS

Thirty-one consecutive patients who experienced left ventricular outflow tract (LVOT)/annular/aortic contained/noncontained rupture during TAVR were collected from 16 centers. A caliper-matched sample of 31 consecutive patients without annular rupture, who underwent pre-TAVR multidetector computed tomography served as a control group. Multidetector computed tomography assessment included short- and long-axis diameters and cross-sectional area of the sinotubular junction, annulus, and LVOT, and the presence, location, and extent of calcification of the LVOT, as well. There were no significant differences between the 2 groups in any preoperative clinical and echocardiographic variables. Aortic root rupture was identified in 20 patients and periaortic hematoma in 11. Patients with root rupture had a higher degree of subannular/LVOT calcification quantified by the Agatston score (181.2±211.0 versus 22.5±37.6, P<0.001), and a higher frequency of ≥20% annular area oversizing (79.4% versus 29.0%, P<0.001) and balloon postdilatation (22.6% versus 0.0%, P=0.005). In conditional logistic regression analysis for the matched data, moderate/severe LVOT/subannular calcifications (odds ratio, 10.92; 95% confidence interval, 3.23-36.91; P<0.001) and prosthesis oversizing ≥20% (odds ratio, 8.38; 95% confidence interval, 2.67-26.33; P<0.001) were associated with aortic root contained/noncontained rupture.

CONCLUSIONS

This study demonstrates that LVOT calcification and aggressive annular area oversizing are associated with an increased risk of aortic root rupture during TAVR with balloon-expandable prostheses. Larger studies are warranted to confirm these findings.

SCCT expert consensus document on computed tomography imaging before transcatheter aortic valve implantation (TAVI)/transcatheter aortic valve replacement (TAVR)

Computed tomography (CT) plays an important role in the workup of patients who are candidates for implantation of a catheter-based aortic valve, a procedure referred to as transcatheter aortic valve implantation (TAVI) or transcatheter aortic valve replacement (TAVR). Contrast-enhanced CT imaging provides information on the suitability of the peripheral access vessels to accommodate the relatively large sheaths necessary to introduce the prosthesis. CT imaging also provides accurate dimensions of the ascending aorta, aortic root, and aortic annulus which are of importance for prosthesis sizing, and initial data indicate that compared with echocardiographic sizing, CT-based sizing of the prosthesis may lead to better results for postprocedural aortic valve regurgitation. Finally, CT permits one to predict appropriate fluoroscopic projections which are oriented orthogonal to the aortic valve plane. This consensus document provides recommendations about the use of CT imaging in patients scheduled for TAVR/TAVI, including data acquisition, interpretation, and reporting.