Diagnosis of acute aortic dissection by D-dimer: the International Registry of Acute Aortic Dissection Substudy on Biomarkers (IRAD-Bio) experience.

BACKGROUND: D-dimer has been reported to be elevated in acute aortic dissection. Potential use as a "rule-out" marker has been suggested, but concerns remain given that it is elevated in other acute chest diseases, including pulmonary embolism and ischemic heart disease. We evaluated the diagnostic performance of D-dimer testing in a study population of patients with suspected aortic dissection. METHODS AND RESULTS: In this prospective multicenter study, 220 patients with initial suspicion of having acute aortic dissection were enrolled, of whom 87 were diagnosed with acute aortic dissection and 133 with other final diagnoses, including myocardial infarction, angina, pulmonary embolism, and other uncertain diagnoses. D-dimer was markedly elevated in patients with acute aortic dissection. Analysis according to control disease, type of dissection, and time course showed that the widely used cutoff level of 500 ng/mL for ruling out pulmonary embolism also can reliably rule out aortic dissection, with a negative likelihood ratio of 0.07 throughout the first 24 hours. CONCLUSIONS: D-dimer levels may be useful in risk stratifying patients with suspected aortic dissection to rule out aortic dissection if used within the first 24 hours after symptom onset.

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.

Cystatin C and risk of mortality among patients undergoing percutaneous coronary intervention.

AIMS: We tested the prognostic value of cystatin C in patients with documented coronary artery disease (CAD) who underwent percutaneous coronary artery intervention (PCI). We also tested the hypothesis that the incremental predictive value of cystatin C on all-cause mortality was superior to that of glomerular filtration rate (GFR) by the Modification of Diet in Renal Disease (MDRD) formula. METHODS AND RESULTS: Included in the study were 2,757 patients (mean age 63 years, 77% men). Blood samples for cystatin C levels were collected immediately before PCI. During a median follow-up of two years, 114 patients died. In multivariable Cox analyses, after adjustment for several confounders, GFR (p=0.004) and cystatin C concentration (p<0.0001) were independent predictors of all-cause death. Cystatin C predicted all-cause death (c-statistic: 0.794) better than GFR estimate based on creatinine (c-statistic: 0.776, p=0.008 for comparison), and significantly reclassified 15% of patients into categories that reflected their actual likelihood of death more accurately (p=0.005). Adding cystatin C and GFR in the same multivariable survival model, only cystatin C level was a significant predictor of death. CONCLUSIONS: This study presents for the first time the incremental predictive value of cystatin C over the creatinine-based MDRD formula on all-cause mortality for CAD patients undergoing PCI.