Whom do you trust? Misguided faith in the catheter- or Doppler-derived aortic valve gradient

Doppler Underestimates Transvalvular Gradient Measured by Catheterization in Patients With Severe Aortic Stenosis

We sought to clarify characteristics of patients with severe aortic stenosis (AS) in whom transvalvular mean pressure gradient (MPG) was underestimated with Doppler compared with catheterization. Study subjects included 127 patients with severe AS who underwent transcatheter aortic valve implantation. Between subjects with Doppler MPG underestimation ≥10 mm Hg (group U) and those without (group C), we retrospectively compared echocardiographic parameters and aortic valve calcification score using the Agatston method. Despite a strong correlation (r_S = 0.88) and small absolute difference (2.1 ± 10.1 mm Hg) between Doppler and catheter MPG, 27 patients (21%) were in group U. Among 48 patients with catheter MPG ≥60 mm Hg, 10 patients (21%) revealed Doppler MPG of 40 to 59 mm Hg, suggesting they had been misclassified as having severe AS instead of very severe AS. According to the guidelines, indication of valve replacement for patients without symptoms should be considered for very severe AS but not for severe AS. Therefore, sole reliance on Doppler MPG could cause clinical misjudgments. Group U had larger relative wall thickness (median [interquartile range: 0.60 [0.50 to 0.69] vs 0.53 [0.46 to 0.60], p = 0.003) and higher calcification score (3,024 [2,066 to 3,555] vs 1,790 [1,293 to 2,501] arbitrary units, p <0.001). Both calcification score (per 100 arbitrary unit increment, odds ratio 1.10, 1.04 to 1.17, p = 0.002) and relative wall thickness (per 0.05 increment, odds ratio 1.29, 95% confidence interval 1.05 to 1.60, p = 0.02) were independently associated with Doppler underestimation. In conclusion, Doppler might underestimate transvalvular gradient compared with catheterization in patients with severe AS who have heavy valve calcification and prominent concentric remodeling left ventricular geometry.

Discrepancies between direct catheter and echocardiography-based values in aortic stenosis

OBJECTIVES

The goal of this article is to examine the correlation of catheter (cath) based and echocardiographic assessment of aortic stenosis (AS) in a community-based academic hospital setting, particularly in the degree that decision to refer for surgery is altered.

BACKGROUND

Current guidelines discourage AS evaluation by invasive pressure measurement if echocardiography (echo) is adequate, but several studies show sizable differences between echo and cardiac catheterization lab (CCL) measurements. We examine this correlation using high quality CCL techniques.

METHODS

Sequential patients with suspected AS by echo (n = 40) aged 61-94 underwent catheterization with pressure gradients via left ventricular pressure wire and ascending aorta catheter. The echos leading to the catheterization were independently reviewed by an expert panel to assess the quality of community-based readings.

RESULTS

CCL changed assessment of severity of aortic valve area (AVA) by more than 0.3 cm(2) in 25% and 0.5 cm(2) in 8%. Values changed to over or under the surgical threshold of AVA < 1 cm(2) in 30% of the patients. Pearson correlation of 0.35 between measurements of AVA by echo and CCL is lower than earlier studies, which often reported correlation values of 0.90 or greater. Echo expert reviews provided minimal improvement in discrepancies (Pearson correlation of 0.46), suggesting quality of initial interpretation was not the issue.

CONCLUSIONS

Cath-echo correlation of AS severity is lower in contemporaneous practice than previously assumed. This can alter the decision for aortic valve replacement. Sole reliance on echo-derived assessment of AS may at times be problematic.