Inconsistent grading of aortic valve stenosis by current guidelines: haemodynamic studies in patients with apparently normal left ventricular function

BACKGROUND: On echocardiography approximately one-third of patients with severe aortic valve stenosis based on aortic valve area (AVA<1.0 cm(2)) demonstrate a non-severe mean pressure gradient (DeltaPm; < or =40 mm Hg) despite apparently normal left ventricular function. It has been suggested that inconsistent echocardiographic grading may be due to 'paradoxical' low stroke volume. However, the correct echocardiographic assessment of stroke volume hinges on the often problematic measurement of the left ventricular outflow tract (LVOT) diameter. OBJECTIVE: To investigate whether inconsistent grading and reduced stroke volume persist when the quantification of aortic valve stenosis is based on cardiac catheterisation which is independent of LVOT measurements. METHODS AND RESULTS: 333 consecutive patients underwent cardiac catheterisation within 30 days after their index echocardiography showing an AVA < or =2 cm(2) and shortening fraction > or =30%. On invasive testing 85 patients (26%) demonstrated inconsistent (AVA<1 cm(2) and DeltaPm< or =40 mm Hg) and 153 (46%) consistent grading (AVA<1 cm(2) and DeltaPm>40 mm Hg) with the remainder (28%) presenting with a calculated AVA> or =1 cm(2). Inconsistently graded patients were older (71 vs 67 years, p<0.006) with no differences in sex or body surface area between groups. Stroke volume and stroke volume index were significantly lower in inconsistently graded patients (63+/-14 vs 73+/-18 ml and 35+/-7 vs 39+/-7 ml/m(2), respectively, both p<0.001). However, 41/85 (48%) of inconsistently graded patients had a normal stroke volume index >35 ml/m(2). CONCLUSION: In the framework of current guidelines inconsistent grading of aortic valve stenosis is common, extends to cardiac catheterisation and is only partially explained by low stroke volume despite apparently normal left ventricular systolic function.