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RAPID ASSAY OF CK-MB SUBFORMS MAY AID DIAGNOSIS OF MI.

A biochemical marker that detected myocardial infarction soon after its onset would refine the use of emergency interventions and coronary care units. Conventional assays for creatine kinase MB may require up to 12 hours for a definitive diagnosis. This study indicates that a new, rapid assay of two subforms of CK-MB is more sensitive during the early hours after MI onset.

Researchers enrolled 1110 patients who presented to an emergency department within 24 hours of developing chest pain at rest. Tests for CK-MB subforms were performed every 30 to 60 minutes until six hours after symptom onset, and were continued every four hours in patients admitted to the hospital.

Of the 660 patients who were admitted, 121 were eventually diagnosed with MI by conventional CK-MB criteria. Of these patients, 56 percent had a positive subform assay at four hours and 96 percent at six hours. In contrast, at six hours the conventional CK-MB assay detected only 48 percent of patients with MI. Only 4 percent of patients who were sent home from the emergency department and 6 percent of admitted patients without MI had positive subform assays.

Comment: The CK-MB subform assay can be performed in 25 minutes at about the same cost as the conventional assay, and appears to be a genuine advance in the early diagnosis of MI. But since these data were generated at a single hospital, the results must be corroborated at other centers.

— AS Brett

Published in Journal Watch General Medicine September 16, 1994

Citation(s):

Puleo PR et al. Use of a rapid assay of subforms of creatine kinase MB to diagnose or rule out acute myocardial infarction. N Engl J Med 1994 Sep 1 331 561-566.

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