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Editorial

Evaluating paravalvular leak after TAVR Deepika Gopalakrishnan,1,2 Ambarish Gopal,1,2 Paul A Grayburn1,2 Aortic regurgitation (AR) after transcatheter aortic valve replacement (TAVR) has been associated with significant adverse outcomes;1–4 therefore, its assessment is clinically important. The most common cause of AR post-TAVR is paravalvular leak (PVL), which occurs if the valve is undersized; annulus geometry is markedly elliptical or the prosthetic valve does not seat properly against the native valve tissue due to excessive calcium or malpositioning. The second Valve Academic Research Consortium-2 (VARC-2) gives recommendations for grading the severity of PVL5 but these are based on expert consensus and not empirically-derived data. Two papers attempt to address the difficult and clinically vexing problem of how to grade the severity of PVL after TAVR.6 7 Both studies compare transthoracic echocardiography (TTE) with cardiac MRI (CMR) for grading severity of PVL. Both pertain to balloon-expandable valves (Sapien, Sapien XT, Sapien 3, Edwards Lifesciences, Irvine, California, USA) using both transfemoral and transapical approaches. Both used a similar methodology for CMR quantitation of regurgitant fraction (RF) and regurgitant volume (RV) by phase contrast imaging. Orwat et al6 compared TTE grading with quantitative flow measurement by CMR with calculation of RF for the assessment of AR. CMR was completed in 59 of 65 consecutive patients a median of 69 days post-TAVR, with both TTE and CMR being done on the same day. TTE grading of PVL as none, mild, moderate or severe was done subjectively by incorporating circumferential extent of the AR jet origin in a short-axis view, jet width in a long-axis view and diastolic flow reversal in the descending aorta. No mention is made of the use of continuous wave Doppler measurements of pressure-half time or end-diastolic velocity (a surrogate of the pressure difference between the aortic and left ventricular end-diastolic pressures). Generally, there was good agreement between CMR and TTE with regard to absence of AR. Overall, there 1

Heart Hospital Baylor Plano, Baylor Jack & Jane Hamilton Heart & Vascular Center and Baylor University Medical Center, Dallas, Texas, USA; 2Baylor Scott & White Healthcare System, Texas, USA Correspondence to Dr Paul A Grayburn, Baylor Heart and Vascular Institute, 621 N. Hall St., Suite H030, Dallas, TX 75226, USA; [email protected]

was only fair agreement between TTE and CMR for AR grading (κ=0.33) with TTE tending to underestimate AR severity. The sensitivity of TTE for moderate AR was only 19% (three of 16 patients). It is not clear whether the TTE misclassifications were clustered among patients with more than one AR jet or whether any particular TTE parameter was superior to others. Inter-observer and intraobserver variability are not presented and the TTE studies appear to have been read by one of two, but not both, experienced echocardiographers. Despite these significant limitations, the study provides support for what clinicians experienced in TAVR strongly suspect: that TTE is excellent for ruling out PVL, but not very good at assessing its severity. Ribeiro et al7 performed baseline evaluation of AR severity in 50 patients prior to TAVR and in 42 of those patients following TAVR. The severity of native AR and PVL was determined by TTE by integration of colour Doppler parameters, including number of AR jets, jet width and circumferential extent of AR in a short-axis view. Inter-observer agreement for TTE was good before and after TAVR (κ=0.85 and 0.82, respectively). However, intraobserver agreement was good before TAVR (κ=0.85) but modest after TAVR (κ=0.68). AR severity by TTE correlated well with CMR measurement of RF and RV in native valves. However, correlation post-TAVR between TTE and CMR was only modest with TTE underestimating the severity of AR. By TTE, 12% of patients had moderate or severe AR post-TAVR compared with 26% of patients by CMR. TTE jet diameter in the parasternal view (R2=0.62) and the multiparametric approach (R2=0.59) showed the best, although only modest, correlations with RF by CMR. There was poor correlation between circumferential extent of prosthetic paravalvular AR (R2=0.36) by TTE and RF by CMR. This probably relates to the low temporal resolution and beam width artefact of colour Doppler, such that one cannot easily distinguish a truly crescent-shaped regurgitant orifice from a markedly eccentric PVL with a small orifice that extends along the annulus and then turns toward the LV outflow tract. Use of other important TTE-derived parameters, such as the continuous wave Doppler profile of AR, flow

Gopalakrishnan D, et al. Heart December 2014 Vol 100 No 24

reversal in the descending aorta and calculation of RF and RV by volumetric methods, was not addressed in this paper. VARC-2 is the current standard used in TAVR research studies.5 It recommends quantitative grading that has been developed and validated for native AR such as effective regurgitant orifice area (EROA) and vena contracta width. Unfortunately, these methods are difficult to apply in paravalvular AR post-TAVR, partly due to shadowing from the prosthetic valves and the native valve calcium and partly because PVL may include multiple jets and irregular, eccentric or serpiginous jets. All these limitations are potentially overcome by CMR. Phase contrast imaging by CMR is an excellent, reproducible and accurate modality to measure RF (aortic backward flow/aortic forward flow×100). The major limitation is that backward flow by CMR includes coronary flow in addition to AR. At rest, coronary blood flow is approximately 40 mL/min and can rise to over 200 mL/min with peak hyperaemia,8 corresponding to roughly 1%–5% of cardiac output. Orwat et al6 considered an RF value 900 TAVR procedures, including balloon-expandable and self-expanding devices. We find that echocardiography is excellent for ruling out paravalvular AR. However, differentiating mild from moderate paravalvular AR is often very difficult, especially when more than one jet is present, or when there is both PVL and central AR. The grading of paravalvular AR post-TAVR continues to remain an unsolved problem with no validated, reproducible, precise measures currently available. The studies by Orwat et al6 and Ribeiro et al,7 despite their limitations, support the growing clinical consensus that echocardiographic grading of PVL is subjective and tends to underestimate AR severity, especially when only colour Doppler imaging is used. While colour Doppler imaging of AR is excellent for ruling out PVL, CMR should be used when PVL is present and of uncertain severity. When a single small round PVL is present posteriorly by colour Doppler, PVL is likely mild and CMR not needed. 1903

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Editorial When multiple jets are present or the orifice is not round, colour Doppler will likely underestimate PVL and CMR should be considered. Unfortunately, pacemakers are common in these patients and may preclude use of CMR. Therefore, future studies should focus on using CMR to validate echocardiographic algorithms for TTE grading of AR post-TAVR. Further studies are needed, with larger numbers of patients and a more thorough echocardiographic approach that includes pressure-half time and end-diastolic velocity of the AR jet by continuous wave Doppler, RV and RF by quantitative Doppler techniques and perhaps 3D echocardiographic measurement of vena contracta area, which is now standard for measuring EROA in mitral regurgitation.9 Hopefully, we can develop a reproducible and accurate method of evaluating PVL post-TAVR. As demonstrated by the studies by Orwat et al6 and Ribeiro et al,7 it is certainly needed. Contributors All authors contributed to conception, writing and editing of this editorial. All have approved the final version. Funding None.

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Competing interests None. Provenance and peer review Commissioned; internally peer reviewed.

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To cite Gopalakrishnan D, Gopal A, Grayburn PA. Heart 2014;100:1903–1904.

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Published Online First 2 September 2014 6

▸ http://dx.doi.org/10.1136/heartjnl-2014-305665 ▸ http://dx.doi.org/10.1136/heartjnl-2014-305615

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Heart 2014;100:1903–1904. doi:10.1136/heartjnl-2014-306390

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from the German transcatheter aortic valve interventions registry. Heart 2011;97:899–906. Hayashida K, Lefevre T, Chevalier B, et al. Impact of post-procedural aortic regurgitation on mortality after transcatheter aortic valve implantation. JACC Cardiovasc Interv 2012;5:1247–56. Kodali SK, Williams MR, Smith CR, et al. Two-year outcomes after transcatheter or surgical aortic-valve replacement. N Engl J Med 2012;366:1686–95. Kappetein AP, Head SJ, Généreux P, et al. Updated standardized endpoint definitions for transcatheter aortic valve implantation: the Valve Academic Research Consortium-2 consensus document. Eur Heart J 2012;22:2403–18. Orwat S, Diller G, Kaleschke G, et al. Aortic regurgitation severity after transcatheter aortic valve implantation is underestimated by echocardiography compared to magnetic resonance imaging. Heart 2014;100:1933–8. Ribeiro H, Le Ven F, Dahou A, et al. Cardiac magnetic resonance versus transthoracic echocardiography for the assessment and quantification of aortic regurgitation in patients undergoing transcatheter aortic valve implantation. Heart 2014;100:1924–32. Gould KL, Johnson NP, Bateman TM, et al. Anatomic versus physiologic assessment of coronary artery disease. Role of coronary flow reserve, fractional flow reserve, and positron emission tomography imaging in revascularization decision-making. J Am Coll Cardiol 2013;62:1639–53. Grayburn PA, Weissman NJ, Zamorano JL. Quantitation of mitral regurgitation. Circulation 2012;126:2005–17.

Gopalakrishnan D, et al. Heart December 2014 Vol 100 No 24

Downloaded from http://heart.bmj.com/ on June 6, 2015 - Published by group.bmj.com

Evaluating paravalvular leak after TAVR Deepika Gopalakrishnan, Ambarish Gopal and Paul A Grayburn Heart 2014 100: 1903-1904 originally published online September 2, 2014

doi: 10.1136/heartjnl-2014-306390 Updated information and services can be found at: http://heart.bmj.com/content/100/24/1903

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Evaluating paravalvular leak after TAVR.

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