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Outcome and Impact of Surgery in Paradoxical Low-Flow, Low-Gradient Severe Aortic Stenosis and Preserved Left Ventricular Ejection Fraction: A Cardiac Catheterization Study
Study Questions:
What are the clinical and hemodynamic features of low-flow, low-gradient (LFLG) severe aortic stenosis (AS) with paradoxical preserved left ventricular ejection fraction (LVEF)?
Methods:
Between 2000 and 2010, 768 patients with preserved LVEF (>50%) and severe AS (valve area ≤1.0 cm2) and without other valve disease underwent cardiac catheterization. Mean age was 74 ± 8 years, 42% were women, and 46% had associated coronary artery disease. The prevalence of LFLG (indexed LV stroke volume <35 ml/m2 and mean gradient <40 mm Hg), normal flow high gradient, normal flow low gradient, and low flow high gradient were 13%, 50%, 22%, and 15%, respectively.
Results:
Compared with patients with normal flow high gradient AS, those with LFLG AS were significantly older, with significantly reduced systemic arterial compliance and vascular resistances, and increased valvuloarterial impedance (all p < 0.05). Ten-year survival was reduced in LFLG AS (32 ± 9%) compared with normal flow high gradient AS (66 ± 4%, p = 0.0002). After adjustment for other risk factors, LFLG AS was independently associated with reduced long-term survival (hazard ratio, 1.85; 95% confidence interval, 1.08-3.07; p = 0.02). However, despite higher operative mortality, patients with LFLG AS undergoing aortic valve replacement seemed to have better long-term survival than those managed conservatively (5-year survival rate 63 ± 6% vs. 38 ± 15%, p = 0.007; hazard ratio, 0.23; 95% confidence interval, 0.09-0.59; p = 0.002).
Conclusions:
This large cardiac catheterization-based study reveals that the LFLG AS entity is not rare, and is associated with worse outcome whether treated medically or surgically. However, these patients may have better long-term survival if treated surgically. The authors concluded that further prospective studies are needed to confirm this finding.
Perspective:
The patient with LFLG severe AS with preserved LVEF presents a diagnostic and therapeutic challenge. Diagnostically, the echo/Doppler diagnosis of LFLG severe AS can be associated with truly severe AS, or with moderate or less AS, but an effective orifice area that erroneously overestimates AS severity (potentially due to mismeasurement of the LV outflow tract, a noncircular LV outflow tract, or proximal displacement of the pulsed-wave sample volume into the LV rather than in the LV outflow tract). This catheter-based study suggests that LFLG severe AS with normal LVEF is not uncommon, and has medical and surgical outcomes even worse than those associated with high gradient severe AS. Because outcomes with aortic valve replacement were better than without, consideration for AVR is appropriate.
Keywords: Heart Valve Prosthesis, Coronary Artery Disease, Ventricular Function, Left, Electric Impedance, Cardiac Catheterization, Coronary Disease, Angioplasty, Balloon, Coronary, Hemodynamics, Echocardiography, Doppler, Vitamin B 6, Survival Rate, Stroke Volume, Vascular Resistance, Confidence Intervals
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