Increased dipeptidyl peptidase 4 in patients with concomitant transthyretin cardiac amyloidosis and severe aortic stenosis.

Background: Due to overlapping symptoms and signs, it can be challenging to diagnose transthyretin amyloid cardiomyopathy (ATTR-CM) in the setting of concomitant aortic stenosis. Biomarkers may discriminate between heart failure with ATTR-CM and heart failure without ATTR-CM, but it is not known if these markers can differentiate between AS with and AS without concomitant ATTR-CM. Methods: In 9 patients with ATTR-CM and AS, 161 patients with lone AS, and 23 healthy controls, we measured 8 plasma proteins previously identified by proteomic analysis as potential candidates for diagnosing ATTR-CM. We assessed differences between groups and association with indices of heart failure and AS severity. Results: Plasma levels of dipeptidyl peptidase 4 (DPP4) were significantly higher in patients with AS and ATTR-CM than in patients with lone AS and in healthy controls. Lower levels of DPP4 were also associated with worse left ventricular function, higher New York Heart Association functional class, and low-flow, low-gradient aortic stenosis. Conclusions: Our findings suggest that DPP4 may be a marker of ATTR-CM in patients with severe AS. In all AS patients, those with and without coexisting ATTR-CM, high DPP4 levels were asociated with better cardiac function.