Low circulating monocyte count is associated with severe aortic valve stenosis.

Background: The pathophysiology of aortic stenosis (AS) involves inflammatory features including infiltration of the aortic valve (AV) by activated macrophages and T cells, deposition of lipids, and heterotopic calcification.

Objectives: To evaluate the correlation between white blood cell (WBC) differential count and the occurrence and progression of AS.

Methods: We identified in our institutional registry 150 patients with AS who underwent two repeated echo studies at least 6 months apart. We evaluated the association between the average of repeated WBC differential counts sampled during the previous 3 years and subsequent echocardiographic AS indices.

Results: There was no significant difference in total WBC, lymphocyte or eosinophil count among mild, moderate or severe AS groups. There was a progressive decrease in monocyte count with increasing AS severity (P = 0.046), more prominent when comparing the mild and severe groups. There was a negative correlation between AV peak velocity or peak or mean gradient and monocyte count in the entire group (r = -0.31, -0.24, and -0.25 respectively, all P < 0.01). Similar partial correlations controlling for age, gender, hypertension, smoking, dyslipidemia and ejection fraction remained significant. The median changes over time in peak velocity and peak gradients in AS patients were 0.44 (0-1.3) m/sec/ year and 12 (0-39) mmHg/year, respectively. There was no correlation between any of the WBC differential counts and the change in peak velocity or peak gradient per year.

Conclusions: Severe AS is associated with decreased total monocyte count. These findings may provide further clues to the mechanism underlying the pathogenesis of aortic stenosis.