Acceleration Time in Aortic Stenosis
2021; Lippincott Williams & Wilkins; Volume: 14; Issue: 1 Linguagem: Inglês
10.1161/circimaging.120.012234
ISSN1942-0080
AutoresSylvestre Maréchaux, Christophe Tribouilloy,
Tópico(s)Coronary Interventions and Diagnostics
ResumoHomeCirculation: Cardiovascular ImagingVol. 14, No. 1Acceleration Time in Aortic Stenosis Free AccessEditorialPDF/EPUBAboutView PDFView EPUBSections ToolsAdd to favoritesDownload citationsTrack citationsPermissions ShareShare onFacebookTwitterLinked InMendeleyRedditDiggEmail Jump toFree AccessEditorialPDF/EPUBAcceleration Time in Aortic StenosisA New Life for an Old Parameter Sylvestre Maréchaux, MD, PhD Christophe TribouilloyMD, PhD Sylvestre MaréchauxSylvestre Maréchaux https://orcid.org/0000-0001-9687-0518 Groupement des Hôpitaux de l'Institut Catholique de Lille, Department of Cardiology, Lille Catholic University, France (S.M.). UR UPJV 7517, Jules Verne University of Picardie, Amiens, France (S.M., C.T.). , Christophe TribouilloyChristophe Tribouilloy Christophe Tribouilloy, MD, PhD, Department of Cardiology, Amiens University Hospital Avenue René Laënnec, 80054 Amiens Cedex 1, France. Email E-mail Address: [email protected] https://orcid.org/0000-0001-7867-3668 Groupement des Hôpitaux de l'Institut Catholique de Lille, Department of Cardiology, Lille Catholic University, France (S.M.). UR UPJV 7517, Jules Verne University of Picardie, Amiens, France (S.M., C.T.). Originally published19 Jan 2021https://doi.org/10.1161/CIRCIMAGING.120.012234Circulation: Cardiovascular Imaging. 2021;14:e012234This article is a commentary on the followingHigher Acceleration/Ejection Time Ratio Predicts Impaired Outcome in Aortic Valve StenosisSee Article by Einarsen et alAccording to current guidelines, aortic stenosis (AS) in patients with preserved left ventricular (LV) ejection fraction is defined as a mean pressure gradient ≥40 mm Hg, corresponding to an aortic valve peak velocity ≥4 m/s or an aortic valve area (AVA) ≤1.0 cm2.1 However, up to 40% of patients may present an AVA in the severe range but without correspondingly high gradients and velocities.2 In such cases of discordant results, once a measurements error has been ruled out, patients who have indeed moderate AS should be differentiated from those with truly severe AS who may benefit from aortic valve replacement. Thus, additional parameters are necessary to refine the diagnostic workup of such AS patients.Severe AS is associated with a delay (tardus) and reduction (parvus) in the upstroke of the aortic pressure, beginning at aortic valve opening, thus resulting in a delay to achieve the maximal instantaneous transvalvular gradient, leading to an increase in acceleration time (AT) by continuous wave Doppler (Figure 1). In addition, although the ejection time (ET) increases in AS, it pseudonormalizes in patients with severe AS when LV dysfunction or low flow occur.3 Therefore, the ratio of AT over ET (AT/ET) integrates AS severity (AT), as well as its consequences on the LV (ET), an increased AT and relatively preserved ET resulting in an increased AT/ET. Indeed, we previously reported that decreased LV function, flow, and concentric geometry of the LV contribute to increase AT/ET beyond AS severity in a large cohort of patients with mild-to-severe AS.4 Importantly, higher systolic blood pressure is associated with a lower AT/ET. Indeed, an increase in systolic blood pressure induces compensatory lengthening of the ET and results in early systolic flow deceleration in the LV outflow tract due to the reflected waves occurring earlier, thereby inducing AT shortening.5Download figureDownload PowerPointFigure 1. Non invasive and invasive assessment of a patient with low-gradient low-flow paradoxical severe aortic stenosis. Doppler (A), catheterism (B), and 3-dimensional (3D) transoesophageal echocardiography data (C). AT indicates acceleration time; AVA, aortic valve area; Echo, echocardiographic; ET, ejection time; KT, catheterism; MPG, mean pressure gradient; SVi, stroke volume indexed to body surface area; and TEE, transesophageal echocardiography.The interest of AT and the AT/ET ratio measured by continuous-wave Doppler flow in AS was first reported by Hatle et al6 in 1980 in a landmark study comparing hemodynamic and noninvasive data from 63 patients with moderate-to-severe AS. Pressure gradients were underestimated in one-third of patients by Doppler versus invasive measurement. The authors showed that a late peak velocity after midsystole helped to refocus the diagnosis toward severe AS. Of note, associated significant aortic regurgitation was associated with earlier peak systolic velocity. Normal values of AT and AT/ET have not been thoroughly investigated. We have observed a median AT and AT/ET (25th to 75th percentile) of 66 (58–75) and 0.24 (0.20–0.27) ms, respectively, in 169 consecutive individuals (median age [25th to 75th percentile], 66 [51–73] years; 62% women) with normal echocardiograms (personal unpublished data). Reanalysis of individual data for the value of AT/ET for the 25 patients with moderate-to-severe AS published by Agatston et al7 in 1985 showed it to strongly correlate with invasive measurement of the mean pressure gradient (r=0.88, P 40 mm Hg. Indeed, both AT and AT/ET correlate with echo Doppler measurements of AS severity and may help to discriminate patients with severe AS.8–11 Although no single cutoff for AT has emerged, an AT/ET ratio >0.34 has been associated with severe AS.10 Interestingly, an elevated AT/ET ratio was recently reported to correlate with an increased computed tomography aortic valve calcium score.4 The case of a 76-year-old hypertensive woman with chronic renal failure is shown in Figure 1. She was diagnosed as having a paradoxical low-flow (stroke volume index, 20 mL/m2), low-gradient (mean gradient, 25 mm Hg) severe AS, despite a preserved LV ejection fraction of 56%. The AT/ET ratio was 0.37. Invasive hemodynamic data confirmed the echocardiographic findings, showing a mean gradient of 26 mm Hg, a stroke volume of 23 mL/m2 at right heart catheterization, and an AVA obtained with the Gorlin formulae of 0.65 cm2. The anatomic AVA was estimated to be 0.69 cm2 by 3-dimensional transesophageal echocardiography.Download figureDownload PowerPointFigure 2. Scatterplot showing the acceleration time (AT)/ejection time (ET) ratio calculated following Doppler and invasive measurement of the mean pressure gradient (MPG) in 25 patients from the report of Agatston et al.7In the present issue of Circulation: Cardiovascular Imaging, Einarsen et al12 present a new post hoc analysis from the SEAS study (Simvastatine and Ezetimibe in Aortic Stenosis)—a randomized prospective controlled study testing the impact of simvastatin and ezetimib on AS progression. This study involved patients with mild-to-moderate AS (aortic peak jet velocity, ≥2.5 and 0.32 was independently associated with the occurrence of major cardiovascular events and, more specifically, cardiovascular death and hospitalization for heart failure in the paradoxical low gradient severe AS group. In addition, an AT/ET ratio >0.32 improved the predictive value of survival models in these patients, for whom therapeutic decision-making is difficult. These results strongly support the value of the AT/ET ratio for risk stratification of patients with asymptomatic AS and highlights the importance of this parameter for daily practice. Ringle Griguer et al13 also reported a positive relationship between increasing AT and an increasing AT/ET ratio and mortality (all cause/cardiovascular) in patients with both symptomatic and asymptomatic moderate-to-severe AS. Although an AT/ET ratio >0.36 was related to a 2.5-fold increased risk of mortality in multivariate analysis, the association between AT and mortality observed by univariate analysis did not remain after adjustment. Altes et al14 observed that an AT/ET ratio >0.36 was associated with a 2-fold increased risk of mortality and an almost 3-fold increased risk of cardiovascular mortality in the challenging group of elderly patients with low-gradient severe AS and preserved LV ejection fraction. This relationship was observed for both patients with either low or normal flow. In clinical practice, adequate determination of the AT/ET ratio requires rigorous methodology. High-fidelity continuous wave Doppler recordings should be obtained using either a dedicated nonimaging continuous wave transducer, if available, or an imaging transducer with continuous wave capabilities. Gains should be decreased, the wall filter increased, and the baseline adjusted and scaled to optimize the signal, with a sweep speed of 100 mm/s. We recommend to first identify the maximum peak velocity, paying attention to avoid noise and fine linear signals. AT is measured from the beginning of flow to the peak aortic jet velocity (Figure 2). ET is measured from the beginning to the end of flow and is sometimes difficult to identify, especially in patients in whom the maximal jet velocity is not recorded from the apical view, thereby potentially resulting in overestimation of the ET. In such cases, the aortic valve closing signal should be used to estimate the ET. The duration of the ET can also be verified in the apical view to check the consistency of the measurement. The measurement of AT/ET must be performed over 3 cardiac cycles in patients in sinus rhythm and can be performed in cases of atrial fibrillation only if the measurement is reproducible between cycles. A low AT/ET ratio should not be used as an indicator of AS severity if systolic blood pressure is abnormally high and should be reassessed after blood pressure normalization. In addition, the AT/ET ratio should not be used as a marker of AS severity in cases of high cardiac output or greater than moderate associated aortic regurgitation, as increased flow shortens the AT and AT/ET ratio. Finally, the AT/ET ratio should be cautiously interpreted in cases of a concomitant significant mitral regurgitation, as it may be lower because of low flow.There are still several issues that need to be addressed. Einarsen et al12 report good reproducibility of this parameter, as have previous reports.13 Such reproducibility should be interpreted with caution, as measurements were performed offline on previously acquired Doppler tracings. A specific test-retest reproducibility study may be more straightforward. Nevertheless, the maximal aortic flow jet velocity may be difficult to obtain using a multiview approach, even in experienced hands.15 Calculation of the AT/ET ratio, although obtained by Doppler, has the advantage of being potentially angle independent. This parameter may be particularly helpful to confirm the AS severity in patients with preserved EF, low-flow, low-gradient, and apparently severe AS, and may raise the possibility that the gradients have been underestimated. The AT/ET ratio is useful in discordant patients with normal flow, low-gradient, and preserved EF, for whom severe AS is unlikely,1 to identify those who may have truly severe AS. Finally, whether the AT/ET ratio can help to discriminate between patients with low-flow, low-gradient AS and low EF from those with truly severe AS and those with pseudostenosis has not been investigated. Previous reports have shown that an AT/ET ratio >0.34 is a strong argument for severe AS.4 The reported prognostic thresholds for the AT/ET ratio in AS vary between studies. The optimal prognostic threshold in the study by Einarsen et al12 was 0.32 in the overall study population and for patients with PLGSAS but was 0.37 for patients with moderate AS. However, the highly predominant inclusion of patients with moderate AS in the study by Einarsen makes determination of an AT/ET prognostic threshold questionable, as the AT/ET ratio increases with AS progression, which varies greatly between patients. An optimal AT/ET threshold of 0.36 was identified in the report of Ringle Griguer et al,13 but the inclusion of some patients with moderate AS in this pilot study also represents a limitation. Further research involving patients with asymptomatic severe AS should be conducted to investigate the optimal AT/ET prognostic threshold that may be used for clinical practice.Disclosures None.FootnotesThe opinions expressed in this article are not necessarily those of the editors or of the American Heart Association.Christophe Tribouilloy, MD, PhD, Department of Cardiology, Amiens University Hospital Avenue René Laënnec, 80054 Amiens Cedex 1, France. Email tribouilloy.[email protected]frReferences1. 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Prospective assessment of the frequency of low gradient severe aortic stenosis with preserved left ventricular ejection fraction: critical impact of aortic flow misalignment and pressure recovery phenomenon.Arch Cardiovasc Dis. 2018; 111:518–527. doi: 10.1016/j.acvd.2017.11.004CrossrefMedlineGoogle Scholar Previous Back to top Next FiguresReferencesRelatedDetailsCited ByAltes A, Thellier N, Bohbot Y, Ringle Griguer A, Verdun S, Levy F, Castel A, Delelis F, Mailliet A, Tribouilloy C and Maréchaux S (2021) Relationship Between the Ratio of Acceleration Time/Ejection Time and Mortality in Patients With High‐Gradient Severe Aortic Stenosis, Journal of the American Heart Association, 10:23, Online publication date: 7-Dec-2021.Related articlesHigher Acceleration/Ejection Time Ratio Predicts Impaired Outcome in Aortic Valve StenosisEigir Einarsen, et al. Circulation: Cardiovascular Imaging. 2021;14 January 2021Vol 14, Issue 1Article InformationMetrics Download: 276 © 2021 American Heart Association, Inc.https://doi.org/10.1161/CIRCIMAGING.120.012234PMID: 33461310 Originally publishedJanuary 19, 2021 KeywordsaortaEditorialsaortic valve stenosisaortic valvedata collectionPDF download SubjectsUltrasoundEchocardiography
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