Discrepancy between gradients derived by cardiac catheterization and by Doppler echocardiography in aortic stenosis: how often does pressure recovery play a role?

Studies have shown very good correlation between Doppler-derived gradients and gradients obtained by cardiac catheterization (cath) in aortic stenosis (AS). However, the phenomenon of pressure recovery may lead to significant overestimation of aortic valve (AV) gradients by Doppler echocardiography (echo). We hypothesized that echo-derived gradients will be higher in mild-moderate AS because of pressure recovery. We studied 94 patients who had echo and cardiac caths in a span of 1 week. The mean age was 72 +/- 13 years, 54% males, 79% had coronary artery disease, and the mean left ventricular ejection fraction was 45 +/- 22%. The mean cardiac output and cardiac indices were 5.1 +/- 1.4/2.7 +/- 0.6 (l/mt), (l/m(2)), respectively. For those with mild AS, echo overestimated gradients in 9.5% of patients (4/42) by an average of 19 mmHg, thus misclassifying the degree of stenosis. In those with moderate AS, 14% (3/21) were misclassified as severe AS (gradient overestimation by an average of 13.6 mmHg). In those with severe AS, echo underestimated gradients in 13% (4/31) by an average of 22.7 mmHg. The aorta at the sinotubular junction was 2.8 cm in those patients with mild AS in whom gradients were overestimated by more than 20 mmHg compared to a sinotubular junction diameter of 3.12 cm in those with mild AS and no overestimation of gradients. The AV area/aortic root ratio was 0.4 in those with mild AS and 0.2 in those with severe AS (P < 0.05).