Abstract 3366: Paradoxical Low Flow, Low Gradient Severe Aortic Stenosis Despite Preserved Ejection Fraction Reflects More Severe Disease and Poorer Prognosis: Implications for Diagnosis and Treatment
Background. Recent studies and current clinical observations suggest that some patients with severe aortic stenosis (AS) on the basis of valve effective orifice area may paradoxically have a relatively low gradient despite the presence of a preserved left ventricular (LV) ejection fraction.
Objective. To document the prevalence, the potential mechanisms, and the clinical relevance of this phenomenon.
Methods. We retrospectively studied the clinical and Doppler-echocardiographic data of 512 patients with severe AS (indexed AVA ≤ 0.6cm2/m2) and a preserved LV ejection fraction (LVEF ≥ 50%).
Results. Of these patients, 331 (65%) had normal LV flow output (NF group) defined as a stroke volume index (SVI) >35ml/m2 and 181 (35%) had paradoxically low flow output (PLF group) defined as SVI ≤35ml/m2. When compared to NF patients, PLF patients had a higher prevalence of female gender (p<0.05), a lower transvalvular gradient (32±17 vs. 40±15 mmHg; p<0.001), a lower LV diastolic volume index (52±12 vs. 59±13 ml/m2; p<0.001), a lower ejection fraction (62±8 vs. 68±7 %; p<0.001), a higher level of LV global afterload reflected by a higher valvulo-arterial impedance (Zva) (5.3±1.3 vs. 4.1±0.7 mmHg.ml-1.m-2; p<0.001) and a lower overall 3-year survival (76% vs. 86%, p=0.006). In multivariate analysis, only age (hazard ratio: 1.06 (95% CI: 1.02–1.09); p=0.0006) and Zva ≥ 5.5 mmHg.ml-1.m-2, (hazard ratio: 2.5 (95% CI: 1.1–5.3); p=0.02) were independently associated with increased mortality.
Conclusion. Patients with severe AS may have low transvalvular gradients despite normal LV ejection fraction. A comprehensive evaluation shows that this pattern is in fact consistent with a more advanced stage of the disease and has a poorer prognosis. Such findings are clinically relevant since these patients may often be misdiagnosed and inappropriately treated.