Prevalence of Patients With Severe Aortic Stenosis, Low Flow And Preserved Ejection Fraction: Results From a Cath-Lab Data Base.

AbstractRecent echocardiographic studies described that almost 30% of patients with severe aortic valve stenosis on the basis of aortic valve area may paradoxically have a relatively low mean gradient despite a preserved left ventricular ejection fraction (EF). However the existence of this pathologic entity has been questioned mainly for the lack of invasive data. We aimed to describe the prevalence of patients with severely reduced aortic valve area and low gradient from a consecutive series of patients with aortic stenosis and normal EF undergoing cardiac catheterization. Sixty one consecutive patients with invasively measured aortic valve area < 0,6 cmq/mq (AHA/ACC definition for severe aortic stenosis) and EF> 50% formed the study population. Each patient underwent to right and left heart catheterization for a comprehensive invasive hemodynamic evaluation. Aortic valve area was measured by Gorlin formula. Cardiac output was measured by thermodilution or Fick method. Low mean gradient was defined < 30 mmHg. 16 % of patients were characterized by low GM despite severely reduced aortic valve area. Patients with low GM were characterized by significantly higher aortic valve area (0.47±0.09 vs 0.36±0.09 cm2/m2; p=0.0008) but similar left ventricular stroke volume (SV) (65±22 vs 65±17 ml; p=0.9) and cardiac output (4.8±1.1 vs 4.7±1.0; p=0.7). The prevalence of low flow (defined as SV < 35 ml/ m2) was similar between groups (50% vs 43%; p=0.3). There was no difference in term of age (78±10 vs 79±11 years; p=0.6), female gender (50% vs 48%; p=0.5), body surface area (1.79±0.4 vs 1.80±0.4; p=0.8), pulmonary artery systolic pressures (37±9 vs 35±11 mmHg; p=0.8), LV end diastolic pressure (16±4 vs 20±7; p=0.1) and mean wedge pressure (17±7 vs 15±7; p=0.2). Patients with low GM showed a higher mean AO pressure (111±14 vs 93±14; p=0.009) but similar level of aortic distensibility (0.78±0.3 vs 0.9±0.4 ml/mmHg; p=0.3). This invasive study confirms that a substantial percent of patients may have a low GM despite a severely reduced aortic valve area and normal EF. It should be acknowledge that the barely perception of this pathologic entity might have reduced the likelihood of patients to undergo catheterization leading to underestimation of the prevalence of this condition.