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Genesis of Paradoxical Low-Flow Low-Gradient Severe Aortic Stenosis | Journal Scan
Study Questions:
Among patients with normal left ventricular ejection fraction (LVEF), is low-flow low-gradient (LFLG) severe aortic stenosis (AS) the end-stage consequence of normal-flow high-gradient (NFHG) AS, or a different entity?
Methods:
Using a large single-center transthoracic echocardiogram (TTE) database, patients with severe AS (aortic valve area <1 cm2) and preserved LVEF (≥50%) were identified; from these, patients were identified with LFLG severe AS (stroke volume index <35 ml/m2 and mean transvalvular gradient <40 mm Hg) and ≥1 additional TTE within 5 years prior to the index TTE. Patients were age/sex/date matched 2:1 with patients with NFHG severe AS and NFLG severe AS who also had ≥1 TTE. The analysis included 1,203 TTEs (383 index studies and 820 preceding studies).
Results:
In 78 patients with LFLG severe AS, a high-gradient stage preceded the index TTE in only four (5%) patients. During the 5 years preceding the index TTE, patients with LFLG severe AS developed increasing relative wall thickness (0.42-0.49, p < 0.001) without change in LV mass index. Patients with NFHG severe AS had a marked increase in LV mass index (87-115 g/m2, p < 0.001). Patients with LFLG severe AS demonstrated the greatest reduction in LV end-diastolic diameters (−3 vs. −1 for NFLG severe AS vs. +2 mm for NFHG severe AS; p = 0.001), deceleration time (−55 vs. −3 vs. +3 ms, respectively; p < 0.01), and LVEF (−4 vs. 0 vs. 0%, respectively; p = 0.01).
Conclusions:
LFLG severe AS is a distinct presentation of severe AS that is preceded by a unique LV remodeling pathway, and is uncommonly preceded by a high-gradient stage.
Perspective:
In clinical practice, the most commonly encountered etiologies of LFLG severe AS remain truly severe AS with low flow despite normal LVEF, and error (in calculating flow and/or effective orifice area, or in documenting the highest transvalvular gradient). Accepting that not all patients with echo/Doppler LFLG severe AS with paradoxical normal EF actually have severe AS, clearly some do. This interesting study provides data suggesting that it is a discrete pattern of LV remodeling that leads to LFLG severe AS with normal LVEF, rather than a stage of high-gradient severe AS.
Keywords: Aortic Valve, Aortic Valve Stenosis, Cardiovascular Surgical Procedures, Deceleration, Diagnostic Imaging, Echocardiography, Doppler, Echocardiography, Heart Valve Diseases, Stroke Volume, Ventricular Function, Left
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