Paradoxical low flow and/or low gradient severe aortic stenosis despite preserved left ventricular ejection fraction: implications for diagnosis and treatment

Abstract

Paradoxical low flow, low gradient, severe aortic stenosis (AS) despite preserved ejection fraction is a recently described clinical entity whereby patients with severe AS on the basis of aortic valve area have a lower than expected gradient in relation to generally accepted values. This mode of presentation of severe AS is relatively frequent (up to 35% of cases) and such patients have a cluster of findings, indicating that they are at a more advanced stage of their disease and have a poorer prognosis if treated medically rather than surgically. Yet, a majority of these patients do not undergo surgery likely due to the fact that the reduced gradient is conducive to an underestimation of the severity of the disease and/or of symptoms. The purpose of this article is to review and further analyse the distinguishing characteristics of this entity and to present its implications with regards to currently accepted guidelines for AS severity.

Figure 1

Illustrative case of patient with PLF AS. (A) Pulse wave (PW) Doppler tracing in LV outflow tract; ITV, time velocity integral; VE, stroke volume; FE, ejection fraction; SVi, stroke volume index. (B) Continuous wave (CW) Doppler tracing through aortic valve; GP, pressure gradient; SVA, aortic valve area; SVAind, aortic valve area indexed for body surface area. (C) Two-dimensional echocardiogram in the parasternal long-axis view in diastole showing heavily calcified valve and small LV with concentric hypertrophy. (D) Pullback pressure tracing from LV to aorta; see text for details.

Figure 2

Characterization of 512 consecutive patients with severe AS (AVAi <0.6 cm²/m²) and preserved ejection fraction (>0.50) based on for SVi > or ≤35 mL/m² and mean pressure gradient > or ≤40 mmHg (data taken from Hachicha et al.). AVA, aortic valve area; AVR, aortic valve replacement; LVEDD, left ventricular end-diastolic diameter; LVDEVI, left ventricular end-diastolic volume index; SVi, stroke volume index; Z_va, valvulo-arterial impedance.

Figure 3

Overall survival in the four groups of patients (Figure 2) as a function of the type of treatment: medical vs. surgical (data taken from Hachicha et al.).