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Diagnostic Implications of Elevated Levels of Smooth-Muscle Myosin Heavy-Chain Protein in Acute Aortic Dissection: The Smooth Muscle Myosin Heavy Chain Study

Toru Suzuki, MD; Hirohisa Katoh, PhD; Yasuhiro Tsuchio, MD; Akira Hasegawa, MD; Masahiko Kurabayashi, MD; Atsushi Ohira, MD; Katsuhiko Hiramori, MD; Yasunari Sakomura, MD; Hiroshi Kasanuki, MD; Shingo Hori, MD; Naoki Aikawa, MD; Satoshi Abe, MD; Chuwa Tei, MD; Yoshihisa Nakagawa, MD; Masakiyo Nobuyoshi, MD; Kazuhiko Misu, MD; Tetsuya Sumiyoshi, MD; and Ryozo Nagai, MD
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Copyright ©2004 by the American College of Physicians

Ann Intern Med. 2000;133(7):537-541. doi:10.7326/0003-4819-133-7-200010030-00013
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Background: A rapid 30-minute assay of circulating smooth-muscle myosin heavy-chain protein has been developed as a biochemical diagnostic tool for aortic dissection.

Objective: To determine the sensitivity and specificity of this assay.

Design: Cross-sectional study.

Setting: 8 major cardiovascular centers in Japan.

Patients: 95 patients with acute aortic dissection, 48 patients with acute myocardial infarction, and 131 healthy volunteers.

Measurements: Levels of circulating smooth-muscle myosin heavy-chain protein.

Results: Patients with acute aortic dissection who presented within 3 hours after onset had elevated levels of circulating smooth-muscle myosin heavy-chain protein. In these patients, the assay had a sensitivity of 90.9%, a specificity of 98% compared with healthy volunteers, and a specificity of 83% compared with patients who had acute myocardial infarction; the clinical decision limit was 2.5 µg/L. All patients with proximal lesions had elevated levels of smooth-muscle myosin heavy-chain protein, and only patients with distal lesions had decreased levels (<2.5 µg/L).

Conclusions: Levels of smooth-muscle myosin heavy-chain protein can be used to diagnose aortic dissection soon after symptom onset. The assay had the greatest diagnostic value in patients with proximal lesions.


Grahic Jump Location
Figure 1.
Sensitivity and specificity of the smooth-muscle myosin heavy-chain assay.Top.Bottom.solid linedotted line

Temporal sensitivity curves according to cutoff levels. The solid line represents a cutoff level of 2.5 µg/L, the dotted line represents a cutoff level of 5.0 µg/L, and the dashed line represents a cutoff level of 10.0 µg/L. Analysis of receiver-operating characteristic curves of patients with aortic dissection compared with healthy volunteers ( ) and patients with acute myocardial infarction ( ). Selected points are shown according to cutoff level (2.5, 5.0, or 10.0 µg/L). For acute myocardial infarction, the following modifications apply: x-axis, 1 − (specificity compared with acute myocardial infarction); y-axis, sensitivity compared with aortic dissection.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Levels of smooth-muscle myosin heavy-chain protein according to type of aortic dissection.Top.solid linedotted lineBottom.

Temporal sensitivity curves for proximal lesions ( ) and distal lesions ( ) at the cutoff level of 2.5 µg/L. Analysis of receiver-operating characteristic curves according to lesion site for patients with aortic dissection compared with healthy volunteers. The solid line indicates proximal lesions, the dotted line indicates distal lesions, and the dashed line indicates all lesions.

Grahic Jump Location




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Summary for Patients

Biochemical Test To Help Diagnose Aortic Dissection

Copyright ©2004 by the American College of Physicians


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