Correspondence

Patients with Acute Chest Pain

N Engl J Med 2000; 343:584-585August 24, 2000

Article

To the Editor:

In their review article on the evaluation of patients with acute chest pain, Lee and Goldman (April 20 issue)1 did not comment on the usefulness of measurements of serum myoglobin. Myoglobin, a relatively small protein (17.8 kd), appears in the peripheral blood much earlier during acute myocardial infarction than other cardiac markers such as creatine kinase MB and troponins. The diagnostic sensitivity of myoglobin levels for acute myocardial infarction ranges from 43 to 100 percent. The wide variability is in large part due to differences in the cutoff values used to define a positive test (ranging from 50 to 150 μg per liter) and in the timing of blood sampling. Because of the protein's early release and rapid clearance, the diagnostic accuracy of myoglobin levels is highly time dependent. In a prospective study involving 309 patients, de Winter et al.2 found that the optimal time to measure serum myoglobin was five hours after the onset of symptoms. With the use of a cutoff value of 50 μg per liter, the serum myoglobin level has a sensitivity of 95 percent and a specificity of 86 percent for the diagnosis of acute myocardial infarction. The sensitivity can be increased to 98 percent (at the expense of a decrease in specificity, to 79 percent) if a cutoff value of 40 μg per liter is chosen.

The usefulness of serum myoglobin levels as a marker for myocardial injury has been limited by its specificity, since elevated myoglobin levels are also found in patients with skeletal-muscle disorders and those with renal failure. However, excellent specificity can be achieved with serial measurements of myoglobin. Polanczyk et al.3 reported that the finding of a doubling of the myoglobin level over a period of two to three hours had a remarkably high specificity of 98 percent. Employing a different diagnostic threshold, Bushnell et al.4 found that a change in the rate of release of myoglobin of more than 20 ng per milliliter per hour had a specificity of 99 percent.

Thus, when applied appropriately, the myoglobin level can be a valuable adjunct in the evaluation of patients with chest pain. For example, the finding of a myoglobin level of less than 40 μg per liter five hours after the onset of symptoms may give physicians in the emergency room the needed confidence to send patients with atypical chest pain home.

Waqas Ahmed, M.D.
T. Michael Fan, M.D., Ph.D.
University of South Alabama Medical Center, Mobile, AL 36617

4 References

1. 1

   Lee TH, Goldman L. Evaluation of the patient with acute chest pain. N Engl J Med 2000;342:1187-1195
   Full Text | Web of Science | Medline

2. 2

   de Winter RJ, Lijmer JG, Koster RW, Hoek FJ, Sanders GT. Diagnostic accuracy of myoglobin concentration for the early diagnosis of acute myocardial infarction. Ann Emerg Med 2000;35:113-120
   CrossRef | Web of Science | Medline

3. 3

   Polanczyk CA, Lee TH, Cook EF, Walls R, Wybenga D, Johnson PA. Value of additional two-hour myoglobin for the diagnosis of myocardial infarction in the emergency department. Am J Cardiol 1999;83:525-529
   CrossRef | Web of Science | Medline

4. 4

   Bushnell A, Woo J, Sunheimer R, McCabe JB. Utility of myoglobin in the evaluation of chest pain in the ED. Am J Emerg Med 1999;17:216-217
   CrossRef | Web of Science | Medline

To the Editor:

It is surprising that a review of the evaluation of acute chest pain would fail to mention psychiatric causes. If cardiac ischemia seems unlikely to be the cause, Lee and Goldman recommend entertaining the possibility of pulmonary, gastrointestinal, musculoskeletal, and other cardiac conditions. Although they single out esophageal disease, they do not discuss the equally common roles of panic disorder and major depression in presentations involving acute chest pain.1

Numerous studies show that up to 30 percent of patients with chest pain have normal coronary angiograms. Katon and colleagues found that 38 percent of angiograms obtained in patients with chest pain and no previously documented heart disease were normal. More tellingly, 70 percent of the patients with normal angiograms met the criteria for panic disorder, major depression, or both, as compared with only 9 percent of the patients with abnormal angio-grams.2 . . .

John Michael Bostwick, M.D.
Mayo Clinic, Rochester, MN 55905

2 References

1. 1

   Cooke RA, Smeeton N, Chambers JB. Comparative study of chest pain characteristics in patients with normal and abnormal coronary angiograms. Heart 1997;78:142-146
   Web of Science | Medline

2. 2

   Katon W, Hall ML, Russo J, et al. Chest pain: relationship of psychiatric illness to coronary arteriographic results. Am J Med 1988;84:1-9
   CrossRef | Web of Science | Medline

Author/Editor Response

The authors reply:

To the Editor: Not every topic can be fully explored in a brief review. We share Ahmed and Fan's interest in myoglobin, and our group has studied this topic.1 Nevertheless, the measurement of myoglobin has not been used routinely in patients with acute chest pain because of its poor specificity and because indexes based on changes in serial myoglobin values do not give clinicians the qualitative guidance (yes vs. no) that they find most useful.

We agree with Dr. Bostwick that panic disorder and depression are common causes of chest discomfort and should be considered in the comprehensive evaluation of patients with typical or atypical chest pain, especially when other causes are not evident. In the acute care setting, however, the primary focus must be on conditions that are potentially life-threatening in the short term.

Thomas H. Lee, M.D.
Partners Community HealthCare, Boston, MA 02199-8001

Lee Goldman, M.D.
University of California, San Francisco, San Francisco, CA 94143-0120

1 References

1. 1

   Polanczyk CA, Lee TH, Cook EF, Walls R, Wybenga D, Johnson PA. Value of additional two-hour myoglobin for the diagnosis of myocardial infarction in the emergency department. Am J Cardiol 1999;83:525-529
   CrossRef | Web of Science | Medline

Citing Articles (1)

Citing Articles

1. 1

   T. W. Lineberry, J. M. Bostwick. (2006) An Opportunity for Parity: Health Care Reform Vis-a-Vis Behavioral Health and Substance Abuse Treatment. Mayo Clinic Proceedings 81:9, 1258-1259
   CrossRef