Preliminary experience with the smooth muscle troponin-like protein, calponin, as a novel biomarker for diagnosing acute aortic dissection

Aims The early diagnosis of acute aortic dissection (AD) remains challenging. We sought to determine the utility of the troponin-like protein of smooth muscle, calponin, as a diagnostic biomarker of acute AD. Methods and results Immunoassays against calponin (acidic, basic, and neutral isoforms) were developed and the levels were compared in a convenience sample of 59 patients with radiographically proven AD [34 males, age 59 +/- 15 (SD) years] vs. 158 patients suspected of having AD at presentation (116 males, age 63 +/- 15 years) but whose final diagnosis was not AD. Basic calponin, which is the most specific and abundant in smooth muscle, and acidic calponin, respectively, showed greater than two-fold and three-fold elevations in patients with acute AD. Diagnostic performance as determined by receiver-operating characteristics curve analysis showed that both acidic and basic calponin have the potential to detect AD in the first 24 h [respective areas under the curve (AUCs) 0.63 and 0.58], with superior performance of basic calponin (when compared with acidic) in the initial 6 h (respective AUCs 0.63 and 0.67). Conclusion Circulating calponin levels were elevated in acute AD compared with controls. These biomarkers have the potential for use as an early diagnostic biomarker for acute AD.