ABC | Volume 110, Nº5, May 2018

Viewpoint Paradoxical Aortic Stenosis: Simplifying the Diagnostic Process Vitor Emer Egypto Rosa, João Ricardo Cordeiro Fernandes, Antonio Sergio de Santis Andrade Lopes, Roney Orismar Sampaio, Flávio Tarasoutchi Instituto do Coração (InCor) - Faculdade de Medicina da Universidade de São Paulo, São Paulo, SP - Brazil Mailing Address: Vitor Emer Egypto Rosa • Av. Dr. Enéas de Carvalho Aguiar, 44, Cerqueira Cesar - São Paulo, SP - Brazil E-mail: vitoremer@yahoo.com.br Manuscript received June 28, 2017, revised mansucript September 27, 2017, accepted October 24, 2017 Keywords Aortic Valve Stenosis; Echocardiography; Aortic Valve. DOI: 10.5935/abc.20180075 Figure 1 – Algorithm proposed for the diagnosis of paradoxical aortic stenosis. * In patients with BMI above 30 kg/m 2 , we must use 0.5 cm 2 /m 2 value as reference for iAVA. AS: aortic stenosis; AVA: aortic valve area; Vel: jet velocity; Grad: gradient; EF: ejection fraction; iAVA: indexed aortic valve area; sBP: systolic blood pressure; CT: computed tomography. Paradoxical AS Recognition AVA ≤ 1.0 cm 2 Vel < 4 m/s ou Grad médio < 40 mmHg EF ≥ 50% Measurement errors evaluation iAVA ≤ 0.6 cm 2 /m 2 Normotensive (BPs < 140 mmHg) Pathophysiology Confirmation Stroke volume < 35 mL/m 2 CT calcification (> 1650 AU) Valve replacement Indication Class IIa, Level of evidence C Severe aortic stenosis (AS) is defined as a significant reduction of the aortic valve area (aortic valve area [AVA] ≤ 1.0 cm²) associated with evidence of left ventricular hypertrophic response (aortic jet velocity > 4 m/s or mean gradient between the left ventricle and the aorta > 40 mmHg). 1-3 However, as Minners et al. 4 have demonstrated, inconsistencies in echocardiographic measurements are extremely frequent in daily clinical practice. In about 30% of the cases evaluated by AS, we found AVA ≤ 1.0 cm², indicative of severe AS, with a mean gradient < 40 mmHg, suggestive of moderate AS. 4 This dissociation makes it difficult to establish an adequate and definitive diagnosis to the patient with AS, fundamental point in the therapeutic decision making. If, on the one hand, patients with moderate AS do not benefit from valve intervention, those with severe AS require surgical aortic valve replacement or a transcatheter aortic bioprosthesis implant, especially if they are symptomatic. 1-3 In 2007, Hachicha et al., 5 in a pioneering work, defined such patients as having "paradoxical AS" (or low-flow, low- gradient AS with preserved ejection fraction). These patients present a pathophysiology similar to that of diastolic heart failure, with hypertrophy and left ventricular compliance reduction, leading to a "low-flow" state, defined by an ejected volume (stroke volume) of < 35 ml/m² (stroke volume = Diastolic Volume - Systolic Volume / Body Surface). 5-7 Another important contribution of Hachicha et al 5 , corroborated by some subsequent studies, 8-11 was the demonstration of a better survival of symptomatic patients with paradoxical AS after valve intervention when compared to clinical treatment. However, patients with paradoxical AS, despite being benefited by valve intervention, present higher surgical mortality when compared with patients with classic AS (mean gradient > 40mmHg). 1-3,8,9,11 In this paper, we propose an algorithm to facilitate the diagnostic confirmation of paradoxical AS. In three steps, we perform the Recognition of Paradoxical AS, Measurement Error Evaluation and Pathophysiological Confirmation (Figure 1): 1. Recognition of Paradoxical AS: this step is the first and most important. The delay in the diagnosis of paradoxical AS causes delayed intervention, leading to an increase in mortality. The classification of "moderate to severe" or even "moderately-severe" valvulopathy is not described in any of the current guidelines and impairs clinical reasoning. 1-3 For this reason, patients with AVA ≤ 1.0 cm², jet velocity < 4 m/s or mean gradient < 40 mmHg and ejection fraction > 50% should be classified as having paradoxical AS or low-flow, low-gradient AS with preserved ejection fraction. 2. Evaluation of Measurement Errors: In this stage, we must identify eventual measurement errors that justify an underestimated gradient or AVA. The echocardiographer should be aware of the correct alignment of the Doppler continuous wave for velocity and gradient measurement, avoiding underestimating these measurements. Another orientation is to avoid AVA measurement by continuity equation and using whenever possible measurement by planimetry. AVA measurement by continuity equation may underestimate AVA, since such measurement takes intoaccount left ventricular outflowtract areacalculation(VSVE)(AVA=areaofVSVExVTIofVSVE/VTI 484