Aortic Valve Calcification Helps Distinguish Severity in Discordant Aortic Stenosis

Howard C. Herrmann, MD

When the valve area says severe but the gradient says moderate, a CT scan might be informative.

Severe aortic stenosis (AS) is typically characterized by small valve area and high gradient (≥40 mm Hg or peak aortic jet velocity of ≥4 m/sec). However, some patients with severe AS based on valve area have low (discordant) gradients, despite normal left ventricular ejection fraction (LVEF) and flow, confounding diagnosis and treatment. In this multicenter study, investigators reviewed echocardiographic and computed tomographic (CT) scans of 646 patients with moderate or severe AS and normal LVEF and identified 172 patients with severe AS by valve area but discordantly low gradients.

Compared with patients with concordant valve-area and gradient findings, patients with discordant findings were less likely to be women and had a lower mean gradient (30 mm Hg) and stroke volume index. The investigators assessed aortic valve calcification on CT scans in patients with concordant findings to define reference values for severe AS; the best threshold for severe AS was 1274 arbitrary units (AU) in women and 2065 AU in men, which yielded positive predictive values of approximately 90%. According to these thresholds, about 50% of patients with discordant findings and a low gradient had calcification loads in the severe-AS range.

Citation(s):

Clavel M-A et al. The complex nature of discordant severe calcified aortic valve disease grading: New insights from combined Doppler echocardiographic and computed tomographic study. J Am Coll Cardiol 2013 Dec; 62:2329.

Dweck MR et al. Small valve area with low-gradient aortic stenosis: Beware the hard hearted. J Am Coll Cardiol 2013 Dec; 62:2339.