Clinical Research
Cardiac Imaging
The Complex Nature of Discordant Severe Calcified Aortic Valve Disease Grading: New Insights From Combined Doppler Echocardiographic and Computed Tomographic Study

https://doi.org/10.1016/j.jacc.2013.08.1621Get rights and content
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Objectives

With concomitant Doppler echocardiography and multidetector computed tomography (MDCT) measuring aortic valve calcification (AVC) load, this study aimed at defining: 1) independent physiologic/structural determinants of aortic valve area (AVA)/mean gradient (MG) relationship; 2) AVC thresholds best associated with severe aortic stenosis (AS); and 3) whether, in AS with discordant MG, severe calcified aortic valve disease is generally detected.

Background

Aortic stenosis with discordant markers of severity, AVA in severe range but low MG, is a conundrum, unresolved by outcome studies.

Methods

Patients (n = 646) with normal left ventricular ejection fraction AS underwent Doppler echocardiography and AVC measurement by MDCT. On the basis of AVA-indexed-to-body surface area (AVAi) and MG, patients were categorized as concordant severity grading (CG) with moderate AS (AVAi >0.6 cm²/m², MG <40 mm Hg), severe AS (AVAi ≤0.6 cm²/m², MG ≥ 40 mm Hg), discordant-severity-grading (DG) with low-MG (AVAi ≤0.6 cm2/m2, MG <40 mm Hg), or high-MG (AVAi >0.6 cm2/m2, MG ≥40 mm Hg).

Results

The MG (discordant in 29%) was strongly determined by AVA and flow but also independently and strongly influenced by AVC-load (p < 0.0001) and systemic arterial compliance (p < 0.0001). The AVC-load (median [interquartile range]) was similar within patients with DG (low-MG: 1,619 [965 to 2,528] arbitrary units [AU]; high-MG: 1,736 [1,209 to 2,894] AU; p = 0.49), higher than CG-moderate-AS (861 [427 to 1,519] AU; p < 0.0001) but lower than CG-severe-AS (2,931 [1,924 to 4,292] AU; p < 0.0001). The AVC-load thresholds separating severe/moderate AS were defined in CG-AS with normal flow (stroke-volume-index >35 ml/m2). The AVC-load, absolute or indexed, identified severe AS accurately (area under the curve ≥0.89, sensitivity ≥86%, specificity ≥79%) in men and women. Upon application of these criteria to DG-low MG, at least one-half of the patients were identified as severe calcified aortic valve disease, irrespective of flow.

Conclusions

Among patients with AS, MG is often discordant from AVA and is determined by multiple factors, valvular (AVC) and non-valvular (arterial compliance) independently of flow. The AVC-load by MDCT, strongly associated with AS severity, allows diagnosis of severe calcified aortic valve disease. At least one-half of the patients with discordant low gradient present with heavy AVC-load reflective of severe calcified aortic valve disease, emphasizing the clinical yield of AVC quantification by MDCT to diagnose and manage these complex patients.

Key Words

aortic valve calcification
aortic valve stenosis
Doppler echocardiography
multidetector computed tomography

Abbreviations and Acronyms

AU
arbitrary units
AVAi
aortic valve area indexed to body surface area
AVC
aortic valve calcification
AVCd
aortic valve calcification indexed to the cross-sectional area of the aortic annulus
AVCi
aortic valve calcification indexed to body surface area
CG
concordant grading
DG
discordant grading
LV
left ventricular
LVEF
left ventricular ejection fraction
LVOT
left ventricular outflow tract
MDCT
multidetector computed tomography
MG
mean gradient
ROC
receiver-operating characteristic
SV
stroke volume
SVi
stroke volume indexed to body surface area
Vmax
peak aortic jet velocity

Cited by (0)

The study was funded in part by grants from the Assistance Publique–Hopitaux de Paris (PHRC national 2005 and PHRC regional 2007) and a grant (MOP# 114997) from the Canadian Institutes of Health Research, Ottawa, Ontario, Canada. Dr. Clavel holds a Vanier Canada Graduate Scholarship and a Michael Smith Foreign Study Supplements Scholarship, Canadian Institutes of Health Research, Ottawa, Ontario, Canada. Dr. Messika-Zeitoun has served as consultant to and received lecture fees from Edwards, Valtech, and Abbott. Dr. Pibarot holds the Canada Research Chair in Valvular Heart Diseases, Canadian Institutes of Health Research. R. Capoulade was supported by a studentship grant of International Chair of Cardiometabolic Risk, Quebec, Quebec, Canada. Dr. Vahanian has received honoraria and/or Speakers fees from Edwards Lifesciences, Abbot, Medtronc, and Valtech. Dr. Enriquez-Sarano has received research support from Abbott Vascular; and has served on the board of Valtech. All other authors have reported that they have no relationships relevant to the contents of this paper to disclose.