ORIGINAL ARTICLE

Cardiac magnetic resonance versus transthoracicechocardiography for the assessment andquantification of aortic regurgitation in patientsundergoing transcatheter aortic valve implantationHenrique B Ribeiro, Florent Le Ven, Éric Larose, Abdellaziz Dahou,Luis Nombela-Franco, Marina Urena, Ricardo Allende, Ignacio Amat-Santos,Maria de la Paz Ricapito, Christophe Thébault, Marie-Annick Clavel,Robert Delarochelliére, Daniel Doyle, Éric Dumont, Jean G Dumesnil, Philippe Pibarot,Josep Rodés-Cabau

▸ Additional material ispublished online only. To viewplease visit the journal online(http://dx.doi.org/10.1136/heartjnl-2014-305615).

Quebec Heart & Lung Institute,Laval University, Quebec City,Quebec, Canada

Correspondence toDr Josep Rodés-Cabau, QuebecHeart & Lung Institute, LavalUniversity, 2725 CheminSte-Foy, Quebec City, Quebec,Canada G1V 4G5;josep.rodes@criucpq.ulaval.ca

Received 29 January 2014Revised 31 May 2014Accepted 17 June 2014

To cite: Ribeiro HB, LeVen F, Larose É, et al. HeartPublished Online First:[please include Day MonthYear] doi:10.1136/heartjnl-2014-305615

ABSTRACTBackground The transthoracic echocardiographic (TTE)evaluation of the severity of residual aortic regurgitation(AR) following transcatheter aortic valve implantation(TAVI) has been controversial and lacks validation.Objectives This study sought to compare TTE andcardiac magnetic resonance (CMR) for assessment of ARin patients undergoing TAVI with a balloon-expandablevalve.Methods TTE and CMR exams were performedpre-TAVI in 50 patients and were repeated postprocedurein 42 patients. All imaging data were analysed incentralised core laboratories.Results The severity of native AR as determined bymultiparametric TTE approach correlated well with theregurgitant volume and regurgitant fraction determinedby CMR prior to TAVI (Rs=0.79 and 0.80, respectively;p<0.001 for both). However, after TAVI, the correlationbetween the prosthetic AR severity assessed by TTE andregurgitant volume and fraction measured by CMR wasonly modest (Rs=0.59 and 0.59, respectively; p<0.001for both), with an underestimation of AR severity by TTEin 61.9% of patients (1 grade in 59.5%). The TTE jetdiameter in parasternal view and the multiparametricapproach (Rs=0.62 and 0.59, respectively; both withp<0.001) showed the best correlation with CMRregurgitant fraction post-TAVI. The circumferential extentof prosthetic paravalvular regurgitation showed a poorcorrelation with CMR regurgitant volume and fraction(Rs=0.32, p=0.084; Rs=0.36, p=0.054, respectively).Conclusions The severity of AR following TAVI with aballoon-expandable valve was underestimated byechocardiography as compared with CMR. The jetdiameter, but not the circumferential extent of the leaks,and the multiparametric echocardiography integrativeapproach best correlated with CMR findings. Theseresults provide important insight into the evaluation ofAR severity post-TAVI.

INTRODUCTIONTranscatheter aortic valve implantation (TAVI) hasbeen established as the gold standard treatment forpatients with severe symptomatic aortic stenosisconsidered inoperable and a reasonable alternative

in those deemed at high risk for conventional surgi-cal aortic valve replacement (SAVR).1 However, theoccurrence of residual aortic regurgitation (AR) sec-ondary to paravalvular leaks (PAR) remains a majorlimitation of the procedure.2 3 The presence ofmoderate or severe residual AR has been associatedwith increased short-term and long-term mortalityfollowing TAVI, and even mild PARs have beenlinked to poorer outcomes.4 5 An accurate evalu-ation of the presence and severity of residual ARpost-TAVI is, therefore, of major prognosticimportance.Doppler-echocardiography has been the most

common method used for AR assessment followingTAVI, but the echocardiographic grading of para-valvular AR is challenging and has not yet beenvalidated.2–4 The limited body of evidence for theechocardiographic parameters and criteria used inthe evaluation of paravalvular AR post-TAVI andthe need for their further validation have beenhighlighted in the recommendations of the ValveAcademic Research Consortium (VARC-2).6

Additionally, the Placement of Aortic TranscatheterValve (PARTNER) trial,7 8 a randomised study thatincluded centrally analysed echocardiography,weighted more heavily on the circumferentialextent of paravalvular AR,9 although this para-meter has neither been well validated.6

Cardiovascular magnetic resonance (CMR) isaccepted as a non-invasive and safe technique thatpermits serial assessment of LV mass, volume andfunction, and it is considered the ‘gold standard’method for measuring these parameters.3 10 11

Furthermore, CMR allows the direct measurementof the severity of AR with high accuracy and repro-ducibility by using the technique of phase-contrastvelocity mapping. This method has been correlatedwith long-term clinical outcomes in patients withnative valve AR.12 However, data on the CMRevaluation of AR in the setting of TAVI have beenlimited to studies including very small number ofpatients who had received most likely a self-expandable valve.13 14 The aim of this prospectivestudy was to compare AR detection and severitygrading using multiparametric transthoracic

Ribeiro HB, et al. Heart 2014;0:1–9. doi:10.1136/heartjnl-2014-305615 1

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Doppler-echocardiography (TTE) approach versus CMR inpatients undergoing TAVI with a balloon-expandable valve.

METHODSStudy populationWe prospectively enrolled 50 patients diagnosed with severesymptomatic aortic stenosis who were accepted for a TAVI pro-cedure at a single Canadian centre. All patients had a CMR per-formed within 7 days (median 1 (1, 2) days) before TAVI, and42 of them had a repeated CMR exam within 30 days (median6 (3–24) days) following TAVI. The reasons to not repeat theCMR exam after TAVI were pacemaker implantation post-TAVI(n=4), death (n=2) and logistic reasons (n=2). TTE examswere performed before the TAVI procedure (median 15 (7, 35)days) and within 30 days (median 6 (6, 22) days) after the pro-cedure. CMR and TTE exams were performed <7 days apartafter TAVI in all cases (median 0 (−1, 5) days) in similar haemo-dynamic conditions. All clinical events during the follow-upperiod were defined according to the VARC-2 criteria.6 Detailsabout the TAVI procedure have been provided elsewhere.1 Allpatients received a balloon-expandable valve (Edwards-SAPIEN,SAPIEN XT or SAPIEN 3 valves, Edwards Lifesciences, Irvine,California). All baseline and procedural characteristics were pro-spectively collected on preset data collection forms. Baselinecomorbidities were defined according to the Society of ThoracicSurgeons predicted risk of mortality criteria and periproceduralevents according to the VARC-2 criteria.6

Doppler-echocardiography measurementsAll TTE exams were analysed in a central echocardiographylaboratory by experienced technicians supervised by a cardiolo-gist. The following measurements were obtained in all patients:aortic annulus diameter, left ventricular ejection fraction (LVEF)calculated with the biplane Simpson method, mean transvalvulargradient calculated with the Bernoulli formula and the valveeffective orifice area calculated by the continuity equation. TheAR was graded using an integrative multiparametric approachbased on semiquantitative and qualitative parameters, whichmainly included visual assessment of the number of jets, jet(s)width (parasternal and apical views) and the circumferentialextent of PAR regurgitation, as recommended by the AmericanSociety of Echocardiography guidelines and the VARC-2,respectively.6 15 16 AR was classified as none/trace, mild, moder-ate and severe.7 8 16 17 The number of AR jets as well as the jet(s) width and extent in the ventricle characteristics were assessedin parasternal short-axis and long-axis views and apical three-chamber and five-chamber views. The jet width was measuredjust below the native or prosthetic valve cusps for central ARand just below the apical border of the prosthetic stent for PAR.In case of disagreement between different echocardiographicparameters in the evaluation of AR severity, a final decision wastaken after assessing and interpreting all parameters. The cir-cumferential extent (%) of the prosthetic PAR was assessed inthe parasternal short-axis view and classified according to thefollowing definition: no or trace (no regurgitant colour flow orpinpoint jet), mild (extent <10%), moderate (extent of 10%–

29%) and severe (extent ≥30%) (figure 1).6

CMR measurementsThe CMR exams were performed using a 1.5 Tesla PhilipsAchieva (Philips Healthcare, Best, The Netherlands) scanneroperating release 2.6 level 3 and dedicated phased-array cardiaccoil during successive end-expiratory breath-holds. Cine imagingof cardiac function was performed by steady-state free

precession technique at 30 phases per cardiac cycle (by vector-cardiographic gating) in 8–14 parallel short-axis and two-chamber, four-chamber and two orthogonal left ventricularoutflow tract (LVOT) planes (8 mm thickness, 0 mm gap).Typical parameters included TR/TE of 3.4/1.2 ms, flip angle40°, number of excitations (NEX) of 1, yielding in-plane spatialresolution of 1.6×2 mm. In addition, through-plane phase-contrast (sQFlow SENSE) imaging was performed in the aortaat the sino-tubular junction. Velocity encoding maximum value(Venc) was set at 200 cm/s. Caution was taken to exclude theprosthesis from acquisition slice to avoid artefacts. However, ifsignificant turbulence, aliasing or prosthesis stent-related arte-facts were seen in the velocity image, the acquisition wasrepeated a few millimetres downstream from the valve and/orwith a higher-velocity window (velocity was increased by 50 cm/s). CMR imaging parameters were the following: TR/TE of4.60–4.92/2.76–3.05 ms, flip angle 15°, 24 phases, pixel spacing1.32–2.07 mm and slice thickness 10 mm and acquisitionmatrix of 256×208. Each phase-contrast velocity mappingacquisition produced two cine images: one magnitude imageand one phase image.

The CMR analysis was performed by two investigators blindedto clinical and TTE results in a central CMR core laboratory. Forassessment of AR, a region of interest identifying the aortic rootwas defined, and flow was integrated for the whole cardiac cycleto provide forward and regurgitant flow through the aortic valveper cardiac cycle. Regurgitant fraction (RF) was calculated asfollows: [regurgitant volume (RV)/total forward volume]×100(figure 1). CMR grades of AR were defined according to RFusing similar reference cut-point values as previously described innative AR as follows: none/trace (RF<5%), mild (5%–19%),moderate (20%–29%) and severe (≥30%).17 LV volumes and EFswere calculated with the use of end-diastolic and end-systolicendocardial semiautomated tracings.

Before TAVI, intraobserver agreement for grading of ARweighted κ was 0.99 for CMR and 0.85 for TTE (p<0.001 forboth). Interobserver agreement weighted κ was 0.96 for CMRand 0.85 for TTE (p<0.001 for both). After TAVI, intraobser-ver agreement weighted κ was 0.99 for CMR and 0.82 for TTE(p<0.001 for both). Interobserver agreement weighted κ was0.92 for CMR and 0.68 for TTE (p<0.001 for both).

Statistical analysisContinuous variables were tested for distribution normality withthe Shapiro–Wilk test and expressed as mean±SD or median(25–75th IQR). Categorical variables are reported as n (%). Forcomparison of baseline and post-TAVI TTE and CMR para-meters, paired Student’s t test or Wilcoxon signed-rank test wasused, based on the distribution of the change in values.Correlations and agreements between CMR and TTE para-meters were assessed by Spearman coefficient, and rates ofagreement were evaluated using the weighted κ and Bowker’stest of symmetry. Comparison of the accuracy of pre-TAVI andpost-TAVI agreement between TTE and CMR was performedwith the generalised linear model. To test the interobserver andintraobserver variability, the measurements in 30 randompatients were repeated after 2 weeks by the same and byanother observer. The weighted κ was used to test the variabil-ity. The results were considered significant with p values <0.05.All analyses were conducted using the statistical package SPSSV.19 (SPSS, Chicago, Illinois, USA).

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RESULTSBaseline and procedural characteristics of the study populationare shown in table 1.

Echocardiographic data at baseline and after TAVIBaseline and post-TAVI TTE characteristics are shown in table 2.According to the multiparametric AR grade, 14.0% of the patientspresented moderate or severe AR at baseline and 11.9% afterTAVI. Also, following TAVI, the presence of AR was paravalvularin all cases, and there were four patients (9.5%) with concomitantmild central AR. According to the circumferential extent of pros-thetic PAR jet(s), nine patients (21.4%) would be considered ashaving moderate AR and seven (16.7%) as severe AR.

CMR data at baseline and after TAVIBaseline and post-TAVI CMR data are shown in table 3. Therewere no significant changes in left and right ventricles dimensionsand functions parameters following TAVI. According to the CMRAR grade, eight patients (19.1%) would be considered as havingmoderate AR and three (7.1%) as severe AR post-TAVI.

Correlation between TTE and CMR AR gradesThe severity of AR at baseline and post-TAVI as determined bymultiparametric TTE approach correlated with the RV and RFas determined by CMR, p<0.001 (figure 2). However, bettercorrelations were observed pre-TAVI than post-TAVI for bothwith RV (Rs=0.79 pre-TAVI vs Rs=0.59 post-TAVI, p<0.001)and RF (Rs=0.80 pre-TAVI vs Rs=0.59 post-TAVI, p<0.001)(table 4). The number of jets and jet width also had modest cor-relation before TAVI (all with p<0.001), and this correlationwas also weaker but still significant (all with p<0.01) afterTAVI. The distribution of RF and RV by CMR after TAVI,according to the number of jets by echocardiography, is shownin online supplementary figure S1. On the other hand, thecircumferential extent of prosthetic PAR measured on the short-axis view showed poor correlation with AR RV and RFmeasured by CMR (RV: Rs=0.32, p=0.084; RF: Rs=0.36,p=0.054). The AR grade defined according to the circumferen-tial extent of PAR (VARC-2)6 also correlated poorly with CMRquantitative parameters of AR (RV: Rs=0.34, p=0.027; RF:Rs=0.33, p=0.034).

Figure 1 Examples of discrepancies between echocardiographic and cardiac magnetic resonance (CMR) quantification of aortic regurgitation (AR).Example 1: transthoracic echocardiography showing jet arc length in the short-axis view that covers >30% of circumference (A) consistent withsevere AR, whereas CMR shows a regurgitant fraction (RF) of 14% (B), which is consistent with mild AR by CMR. Example 2: transthoracicechocardiography showing jet arc length in the short-axis view that covers 10%–20% of circumference (C) consistent with moderate AR, while CMRshowed a RF of 36%, which is consistent with severe AR.

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The agreement between TTE and CMR grades was strongerbefore TAVI (weighted κ=0.766, p<0.001) as compared withpost-TAVI (weighted κ=0.300, p=0.375) (figure 3). Eighty percent of the patients had the same AR grade at TTE and CMRbefore TAVI versus 33.3% after TAVI, and this difference wasstatistically significant (p<0.001). Before TAVI, discrepancies inAR grade were essentially found between grade none/trace andmild (16%) with both under and overestimation (12% and 4%,respectively), and no more than one grade change. After TAVI,

the TTE AR grade (multiparametric) was lower than CMRgrade in a large proportion of patients (61.9%) reaching onegrade in 59.5% and two grades in 2.4% (figure 3).Furthermore, in 14.3% (n=6) of the patients, AR was evaluatedas ≤ mild by TTE but was classified as ≥ moderate by CMR(figure 3). Finally, concordance between circumferential extentof AR by TTE (VARC-2) and CMR AR grade was also poor(45.2%) after TAVI, with overestimation and underestimation ofat least one grade in 16 (38.1%) and 7 (16.7%) patients,respectively (figures 1 and 4).

DISCUSSIONDespite recent advances in the transcatheter heart valve systemsand the increasing experience of the centres/operators, TAVI isstill associated with a much higher rate of PAR as comparedwith SAVR.2 3 18 Nonetheless, there has been considerable vari-ability in the frequency and severity of PAR after TAVI, with arate of moderate/severe AR ranging from none to as much as24%.2 3 Several factors such as the use of different imagingmodalities between studies (transthoracic vs transesophagealechocardiography, 2D vs 3D echocardiography or angiography),timing of assessment and the absence of standardised criteria

Table 1 Clinical and procedural characteristics of the studypopulation

Variable All patients (n=50)

Clinical variablesAge (years) 79±7Male sex 28 (56)BMI (kg/m2) 28.4±4.6NYHA class

I–II 16 (32)III–IV 34 (68)

Diabetes 15 (30)Hypertension 41 (82)Coronary artery disease 32 (64)Prior CABG 21 (42)History of atrial fibrillation 16 (32)Cerebrovascular disease 7 (14)Peripheral vascular disease 14 (28)COPD 17 (34)eGFR (mL/min) 66.2±20.8LogEuroSCORE (%) 22±13.9STS-PROM (%) 6±3.7

Procedural variablesSuccess* 45 (90)Approach

Transapical 16 (32)Transfemoral 29 (58)Transaortic 5 (10)

Prosthesis typeSapien 9 (18)Sapien XT 39 (78)Sapien 3 2 (4)

Prosthesis size (mm)20 1 (2)23 21 (42)26 17 (34)29 11 (22)

Valve-in-valve 9 (18)30-day outcomesNew pacemaker 4 (8)Major vascular complications 2 (4)Major or life-threatening bleeding 8 (16)Acute renal failure 2 (4)Stroke 1 (2)Death 2 (4)Hospitalisation length (days) 8 (4.8, 11.5)

Values are n (%), mean (±SD) or median [IQR].*Following VARC-2 criteria.6

BMI, body mass index; NYHA, New York Heart Association; CABG, coronary arterialbypass graft; COPD, chronic obstructive pulmonary disease; eGFR, estimatedglomerular filtration; LogEuroSCORE, logistic EuroSCORE predicted risk of mortality;STS-PROM, Society of Thoracic Surgeons predicted risk of mortality; VARC, ValveAcademic Research Consortium.

Table 2 Baseline and post-TAVI transthoracic echocardiographycharacteristics of the study population

Variable

Baseline (n=50)LVEF (%) 53±13Peak gradient (mm Hg) 69±23Mean aortic gradient (mm Hg) 41±15Aortic valve area (cm2) 0.70±0.22PSAP (mm Hg) 41±13Moderate/severe mitral regurgitation 11 (22)Multiparametric AR gradeNone/trace 17 (34)Mild 26 (52)Moderate 5 (10)Severe 2 (4)

Post-TAVI (n=42)LVEF (%) 53±12Peak gradient (mm Hg) 24±13Mean aortic gradient (mm Hg) 13±8Aortic valve area (cm2) 1.48±0.53PSAP (mm Hg) 44±13Moderate/severe mitral regurgitation 10 (23.8)Multiparametric AR gradeNone/trace 26 (61.9)Mild 11 (26.2)Moderate 4 (9.5)Severe 1 (2.4)

Circumferential extent of prosthetic paravalvularregurgitation (%)

12.8 (4.7, 25)

AR grade based on circumferential extent (using VARC-2 criteria)None/trace 16 (38.1)Mild 10 (23.8)Moderate 9 (21.4)Severe 7 (16.7)

Values are n (%), mean (±SD) or median [IQR].TAVI, transcatheter aortic valve implantation; LVEF, left ventricular ejection fraction;PSAP, pulmonary systolic arterial pressure; AR, aortic regurgitation; VARC, ValveAcademic Research Consortium.

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Table 3 Baseline and post-TAVI cardiac magnetic resonance (CMR) characteristics of the study population

Variable Pre-TAVI Post-TAVI p Value

Baseline (n=42) (n=42)LV end diastolic volume (mL) 146.3±47.4 156.5±60.6 0.656LV end systolic volume (mL) 65.7±44.9 72±54.3 0.897LV cardiac output (L/s) 5.6±1.2 6.1±1.3 0.076LVEF (%) 58.5±14.6 57.7±14.4 0.907LV mass (g) 116.6±36.9 124±34.2 0.186RV end diastolic volume (mL) 114±35.1 126.9±47.1 0.223RV end systolic volume (mL) 52.2±26.6 61.6±43.3 0.406RV cardiac output (mL) 4.3±1.1 4.8±1.4 0.064RVEF (%) 55.9±11.4 54.3±13.6 0.887Total forward volume (mL) 59.1±15.3 66.3±18.5 0.044Regurgitant volume (mL) 4.5 (2, 10.8) 6 (3, 10) 0.195Regurgitant fraction (%) 9 (3.8, 17.3) 9.5 (6.8, 20.1) 0.580Aortic regurgitation according to CMR –

None/trace 13 (31) 9 (21.4)Mild 22 (52.4) 22 (52.4)Moderate 4 (9.5) 8 (19.1)Severe 3 (7.1) 3 (7.1)

Values are n (%) or mean (±SD).TAVI, transcatheter aortic valve implantation; LV, left ventricular; LVEF: LV ejection fraction; RV, right ventricular; RVEF, RV ejection fraction.

Figure 2 Quantification of regurgitant volume (A and B) and fraction (C and D) as determined by cardiac magnetic resonance, according to theaortic regurgitation (AR) grade as determined by a multiparametric echocardiography evaluation before (A and C) and after transcatheter aorticvalve implantation (TAVI; B and D). Data presented as median (IQR 25–75) and errors bars represent 95% CI.

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and a central echocardiography core laboratory to evaluate PARmay in part explain these differences.

In the PARTNER trial cohorts A and B, the incidence ofresidual moderate/severe AR was of 12.2% and 11.8%, respect-ively, which is similar to the 11.9% observed in our study usinga central core laboratory evaluation.7 8 19 However, the rate ofmoderate/severe AR post-TAVI as evaluated by CMR was abouttwofold higher (∼26%). To date, there have been very few dataevaluating AR by CMR after TAVI. In a previous small studyperformed exclusively in patients receiving a self-expandablevalve, moderate/severe AR as evaluated by CMR was observedin 12.5% of the patients.13 This may be explained by the factthat although AR quantification was performed by phase-contrast sequences, AR severity cut-points were chosen accord-ing to a prior study that used only a volumetric method. Thisled to higher cut-point values (ie, >30% for AR grades III andIV) and may have been influenced by concomitant valvular dis-eases such as mitral regurgitation, which is very frequent inpatients referred for TAVI.20 Interestingly, a recent study usingthe same CMR methodology as in the present study (phase-contrast) in patients treated with both self-expandable andballoon-expandable valves, the rate of moderate/severe AR was19%,14 consistent with our results.

The discrepancies in AR severity grading between TTE andCMR might be, in part, due to the fact that the PAR jets areoften multiple, eccentric and of irregular shape.9 15 16

Furthermore, they are not free jets in the centre of the LVOTbut are often confined against the LVOTwall. Acoustic shadow-ing from the annulus and LVOT calcifications and Dopplerattenuation from the prosthetic valve stent may further jeopard-ise accurate quantification of regurgitant jets and may result inan underestimation of AR severity. Indeed, up to 14% of thepatients with moderate/severe AR as determined by CMR wereclassified by TTE as AR grade ≤ mild, which is consistent with

the results of a previous study using self-expandable valves.21

This inaccurate quantification of AR grade may also explainwhy even mild AR has been related to increased mortality at2 years in the PARTNER trial.5

In the PARTNER trial,7 8 the severity of residual AR wasgraded according to the American Society of Echocardiographyrecommendations for native valves,16 but the circumferentialextent of prosthetic PARs was weighted more heavily than otherparameters for the final assessment of AR grade.9 Importantly,the present study revealed that this parameter has a poor correl-ation with CMR parameters of AR, mainly due to an overesti-mation of the severity of AR. In fact, PAR jet diameter showed abetter correlation with CMR parameters for the evaluation ofAR severity post-TAVI, similar to that obtained with the use ofmultiparametric TTE AR grading. Still, these methods in TTEpresented a poor agreement with CMR AR grade classification,highlighting that multiple parameters and imaging modalitiesmay be considered in the sake of proper grade classification, butnot to rely only on the circumferential extent of PAR.

CMR allows accurate and highly reproducible estimation ofAR through a direct quantitative assessment of the regurgitationvolume and fraction, irrespective of the number and eccentricityof regurgitant jets and the presence of concomitant valve dis-eases.13 14 17 22 However, the higher costs, lower availabilityand the presence of relative or absolute contraindications inmany patients (eg, those with pacemakers) make CMR unlikelyto replace TTE as the primary modality for assessment of PARand AR grading after TAVI. The results of the present studyhighlight the potential role of CMR in those patients in whomthere is a discrepancy between TTE assessment of transcathetervalve AR and patient’s clinical status. The findings of this studyalso emphasise the need for improving the accuracy of echocar-diography for assessment of PAR severity. To this effect, themeasurement of the left and right outflow tract stroke volumesmay help to improve the estimation of AR RV (differencebetween left and right stroke volumes) and thus the quantitationof AR severity by TTE. Also 3D transthoracic or transesopha-geal echocardiography may enhance the detection and quantita-tion of PAR jets.22 23

LimitationsEven though this is to date the largest cohort of patients evalu-ated with CMR before and after TAVI, the patients were notconsecutive and a selection bias might have played a role in theresults. However, the fact that TTE results were similar to thoseobtained in previous studies including native aortic valve andpost-TAVI patients makes this possibility unlikely. In the contextof PAR, many of the quantitative or semiquantitative parametersproposed in the American Society of Echocardiography/European Association of Echocardiography guidelines15 aredifficult or impossible to measure (eg, vena contracta width, jetwidth to LVOT diameter ratio) or are less reliable (eg, pressurehalf time of the continuous wave AR envelope, flow reversal inthe descending aorta) due to the acute nature of the regurgita-tion and the reduced compliance of the LV. There is still a lackof a definitive gold standard for the measurement of AR in thecontext of TAVI. In the present study, we used CMR as the goldstandard and this is supported by previous studies in native ARshowing high reproducibility and accuracy, the fact that CMRmeasurements may be performed away from the site of valveimplant and the good correlation of RF as evaluated by CMRwith clinical outcomes in native aortic valves.12 Nonetheless,the limited number of patients and the lack of long-termfollow-up did not allow us to determine a RF cut-off associated

Table 4 Correlation between parameters of aortic regurgitationmeasured by transthoracic echocardiography and cardiac magneticresonance

Variable

Pre-TAVI Post-TAVI

Rs p Value Rs p Value

Regurgitant volume (mL)Multiparametric AR grade 0.79 <0.001 0.59 <0.001Number of jets 0.60 <0.001 0.47 0.002

AR jet(s) widthParasternal long-axis view 0.64 <0.001 0.64 <0.001Apical views 0.74 <0.001 0.45 0.003

Circumferential extent of paravalvularregurgitation (%)

– – 0.32 0.084

AR grade based on circumferential extent(VARC-2 criteria)

– – 0.34 0.027

Regurgitant fraction (%)Multiparametric AR grade 0.80 <0.001 0.59 <0.001Number of jets 0.60 <0.001 0.50 0.001AR jet(s) Width

Parasternal long-axis view 0.68 <0.001 0.62 <0.001Apical views 0.77 <0.001 0.49 0.001

Circumferential extent of paravalvularregurgitation (%)

– – 0.36 0.054

AR grade based on circumferential extent(VARC-2 criteria)

– – 0.33 0.034

AR, aortic regurgitation; TAVI, transcatheter aortic valve implantation; VARC, ValveAcademic Research Consortium.

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Figure 3 Comparison of the aorticregurgitation grade as determined by amultiparametric echocardiographicapproach in relation to the gradeclassification with cardiac magneticresonance pre-transcatheter aorticvalve implantation (TAVI) (A) andpost-TAVI (B).

Figure 4 Comparison of the aorticregurgitation (AR) grade as determinedby circumferential extent of prostheticparavalvular regurgitation in relation tothe AR grade classification withcardiac magnetic resonancepost-transcatheter aortic valveimplantation.

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with poorer clinical outcomes. Thus, future studies with a largernumber of patients will have to appraise the accuracy of ARmeasurement by CMR and its correlation with clinical out-comes. The results of this study were obtained in patients under-going TAVI with a balloon-expandable valve and may not applyto those patients receiving a self-expandable valve.

CONCLUSIONSIn patients undergoing TAVI with a balloon-expandable valve,TTE may underestimate or overestimate the severity of residualAR as compared with CMR in a substantial proportion ofpatients. Although modest, the multiparametric TTE integrativeapproach showed the best correlation with AR severity deter-mined by CMR. On the other hand, the circumferential extentof prosthetic PAR correlated poorly with the CMR AR severity.The use of CMR in selected patients, particularly in those exhi-biting discordances between echocardiography results and clin-ical outcomes, might help to better quantify the AR grade, andthis may in turn translate into the implementation of additionalmeasures (PAR closure, valve-in-valve, SAVR) to improve clinicaloutcomes.

Key messages

What is already known on this subject?The occurrence of residual aortic regurgitation (AR) secondary toparavalvular leaks remains a major limitation of thetranscatheter aortic valve implantation (TAVI) procedure.However, the evaluation of the severity of residual AR bytransthoracic echocardiography (TTE) is challenging and has notyet been well validated.

What might this study add?The echocardiographic grading of AR in native aortic valvedisease showed a good correlation with cardiac magneticresonance (CMR). However, this correlation decreased and wasonly modest following TAVI, with an underestimation of ARseverity by TTE as compared with CMR. The jet diameter andthe multiparametric echocardiography integrative approach, butnot the circumferential extent of the leaks, best correlated withCMR findings after TAVI.

How might this impact on clinical practice?The present results highlight the challenges of an accurateevaluation of AR after TAVI. The use of a multiparametricechocardiography approach, rather than a single parameter suchas the circumferential extent of prosthetic AR, should beconsidered for the accurate quantification of AR post-TAVI. Also,CMR may help to better quantify the AR grade in selectedpatients, such as for those exhibiting discordances between TTEresults and clinical outcomes.

Contributors All authors have read and approved submission of the manuscript.All authors have contributed to this work as follows: substantial contributions to theconception and design, acquisition of data or analysis and interpretation of data;drafting the article or revising it critically for important intellectual content; and finalapproval of the version to be published.

Funding This study was funded, in part, by research grants (MOP-57745 and MOP126072) from the Canadian Institutes of Health Research (CIHR). HBR is supportedby a research PhD grant from ’CNPq, Conselho Nacional de DesenvolvimentoCientífico e Tecnológico—Brasil’. FLV is supported by a clinical and research

fellowship from the ’Fédération Française de Cardiologie’. LN-F received funding viaa research grant from the ’Fundación Mutua Madrileña’ (Spain). IA-S was supportedby the ’Instituto de Salud Carlos III’, through a research contract at the Institute ofHeart Sciences (Valladolid, Spain). M-AC is supported by a postdoctoral fellowshipfrom CIHR. PP holds the Canada Research Chair in Valvular Heart Disease supportedby CIHR.

Competing interests RD is consultant for St. Jude Medical. ED is consultant forEdwards Lifesciences. JR-C is consultant for Edwards Lifesciences and St. JudeMedical.

Ethics approval The study protocol was performed in accordance with theinstitutional ethics committee.

Provenance and peer review Not commissioned; externally peer reviewed.

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doi: 10.1136/heartjnl-2014-305615 published online August 14, 2014Heart

 Henrique B Ribeiro, Florent Le Ven, Éric Larose, et al. transcatheter aortic valve implantationregurgitation in patients undergoing assessment and quantification of aortictransthoracic echocardiography for the Cardiac magnetic resonance versus

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