0

The full content of Annals is available to subscribers

Subscribe/Learn More  >
Articles |

Incremental Value of the Leukocyte Differential and the Rapid Creatine Kinase-MB Isoenzyme for the Early Diagnosis of Myocardial Infarction

Stephen P. Thomson, MD; Raymond J. Gibbons, MD; Peter A. Smars, MD; Vera J. Suman, PhD; Robert V. Pierre, MD; Paula J. Santrach, MD; and Nai-Siang Jiang, PhD
[+] Article and Author Information

From Mayo Clinic and Mayo Foundation, Rochester, Minnesota. Requests for Reprints: Raymond J. Gibbons, MD, Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic, 200 First Street SW, Rochester, MN 55905. Acknowledgments: The authors thank the nurses and physicians of the emergency department and inpatient cardiovascular units, the technical staff of the laboratories, and Drs. Hugh C. Smith and Robert L. Frye for their review of the questionable cases.


Copyright ©2004 by the American College of Physicians


Ann Intern Med. 1995;122(5):335-341. doi:10.7326/0003-4819-122-5-199503010-00003
Text Size: A A A

Objective: To test whether automated measurements of cortisol-induced changes in the leukocyte differential can provide an early marker of myocardial infarction, especially when combined with the rapid creatine kinase-MB isoenzyme.

Design: A prospective, blinded study of these measurements at the time of initial assessment in the emergency department.

Setting: Large multispecialty clinic hospital.

Patients: 511 consecutive patients presenting to the emergency department with chest pain. One hundred twenty-seven patients with infection, trauma, or metastatic cancer or receiving myelosuppressive or glucocorticoid therapy were excluded.

Measurements: Automated leukocyte differentials, rapid creatine kinase-MB levels, cortisol levels, and routine clinical measurements.

Results: Of 69 patients with myocardial infarction, only 39% had diagnostic electrocardiographic ST-segment elevation. ST-segment elevation had a specificity of 99% and a positive predictive value of 93%. A relative lymphocytopenia (lymphocyte decrease <20.3%) or elevated rapid creatine kinase-MB level (>4.7 ng/mL) was more sensitive than ST-segment elevation (sensitivities of 58% and 56%, respectively) but less specific (specificities of 91% and 93%, respectively). The presence of both a relative lymphocytopenia and an elevated rapid creatine kinase-MB level had a sensitivity of 44%, a specificity of 99.7%, and a positive predictive value of 97% (95% CI, 80% to 99%). Both a relative lymphocytopenia and an elevated rapid creatine kinase-MB level were independent (P < 0.001) predictors of infarction in patients without ST-segment elevation. If myocardial infarction was suspected by the presence of both abnormal markers or ST-segment elevation, the sensitivity for early diagnosis increased from 39% (ST elevation alone) to 65% (CI, 52% to 76%); the specificity was 99%; and the positive predictive value was 94% (CI, 82% to 98%).

Conclusions: The presence of both a relative lymphocytopenia and an elevated rapid creatine kinase-MB level was an accurate early marker of myocardial infarction that appeared to improve the sensitivity of early diagnosis compared with that of ST-segment elevation alone.

Figures

Grahic Jump Location
Figure 1.
Flow diagram showing patient selection and the prevalence of ST-segment elevation and positive serum markers (defined as both a relative lymphocytopenia and an elevated rapid creatine kinase-MB level) in patients with and patients without myocardial infarction.

In one patient with infarction and no ST-segment elevation, the rapid creatine kinase-MB level was not measured.

Grahic Jump Location
Grahic Jump Location
Figure 2.
Peripheral blood leukocyte counts. Top.Bottom.9

Sixty-nine patients with infarction and positive (□) or negative (●) electrocardiograms. Three hundred fifteen patients without infarction (●). The dashed line represents the relative lymphocyte (lymph) concentration of 20.3%. The dotted line represents the upper limit of normal for total leukocyte count, 10.9 × 10 /L.

Grahic Jump Location
Grahic Jump Location
Figure 3.
Relative lymphocyte percentages and rapid creatine kinase-MB levels. Top.Bottom.

Patients with acute myocardial infarction and positive (squares) or negative (circles) electrocardiograms. Patients without infarction (circles). Both values were available in 307 patients without infarction and in 68 with infarction. The dashed lines represent the lower limit of normal for the relative lymphocyte percentage and the upper limit of normal for rapid creatine kinase-MB (CK-MB) levels.

Grahic Jump Location
Grahic Jump Location
Figure 4.
Combinations of results for relative lymphocyte percentages and rapid creatine kinase-MB levels.topbottom

Patient subgroups were determined by relative lymphocyte percentages (lymph) and rapid creatine kinase-MB (CK-MB) levels; + indicates abnormal results; −indicates normal results. The number of patients with each combination of relative lymphocyte percentages and creatine kinase-MB levels ( ) and the prevalence of acute myocardial infarction ( ) are shown.

Grahic Jump Location

Tables

References

Letters

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Comments

Submit a Comment
Submit a Comment

Summary for Patients

Clinical Slide Sets

Terms of Use

The In the Clinic® slide sets are owned and copyrighted by the American College of Physicians (ACP). All text, graphics, trademarks, and other intellectual property incorporated into the slide sets remain the sole and exclusive property of the ACP. The slide sets may be used only by the person who downloads or purchases them and only for the purpose of presenting them during not-for-profit educational activities. Users may incorporate the entire slide set or selected individual slides into their own teaching presentations but may not alter the content of the slides in any way or remove the ACP copyright notice. Users may make print copies for use as hand-outs for the audience the user is personally addressing but may not otherwise reproduce or distribute the slides by any means or media, including but not limited to sending them as e-mail attachments, posting them on Internet or Intranet sites, publishing them in meeting proceedings, or making them available for sale or distribution in any unauthorized form, without the express written permission of the ACP. Unauthorized use of the In the Clinic slide sets will constitute copyright infringement.

Toolkit

Buy Now

to gain full access to the content and tools.

Want to Subscribe?

Learn more about subscription options

Advertisement
Related Articles
Related Point of Care
Topic Collections
PubMed Articles

Buy Now

to gain full access to the content and tools.

Want to Subscribe?

Learn more about subscription options

Forgot your password?
Enter your username and email address. We'll send you a reminder to the email address on record.
(Required)
(Required)