Feasibility and reliability of rapid diagnosis of myocardial infarction.
BACKGROUND
Prevailing hospital practice dictates a protracted phase of observation for patients with chest pain to establish or exclude the diagnosis of myocardial infarction. Early diagnosis of acute myocardial infarction may improve patient care and reduce both complications and hospital costs. A study was performed to investigate the feasibility of early diagnosis of myocardial infarction within the first 9 hours of the hospital stay.


METHODS
The records of all patients admitted with chest pain within one calendar year were analyzed. The timing of creatine kinase-MB (CK-MB) quantification was determined with reference to the initial phlebotomy (time 0). An enzymatic diagnosis of myocardial infarction was assigned if any determination of CK-MB exceeded the upper limit of normal, and the diagnosis of each patient at or before 9 hours (early diagnosis) was compared to the ultimate diagnosis at 14 to 24 hours (final diagnosis) beyond initial assessment.


RESULTS
Of the 528 included patients, 523 patients (99.1%) had identical early and final diagnostic outcomes; 5 patients (0.9%) had conflicting results. An early diagnosis of myocardial infarction was assigned to 195 of the 528 patients (36.9%). Of these, 190 achieved the diagnosis within 9 hours (sensitivity 97.4%). The negative predictive value was 98.5%.


CONCLUSIONS
Standard CK-MB mass measurements within 9 hours of arrival provided an accurate clinical assessment in > 99% of the cases. The high sensitivity and negative predictive values suggest that early diagnosis of myocardial infarction is feasible and reliable.
Engel
G
G
Division of Cardiovascular Medicine, Stanford University School of Medicine, California 94305, USA.
Rockson
S G
SG
D000368:Aged; D000369:Aged, 80 and over; D002637:Chest Pain; D003402:Creatine Kinase / Q000097:blood*; D052279:Creatine Kinase, MB Form; D005240:Feasibility Studies; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000097:blood*; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis*; D009211:Myoglobin / Q000097:blood; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013997:Time Factors; D019210:Troponin I / Q000097:blood
D007527:Isoenzymes; D009211:Myoglobin; D019210:Troponin I; D003402:Creatine Kinase; D052279:Creatine Kinase, MB Form