Circulation, Vol 65, 918-923, Copyright © 1982 by American Heart Association
Myocardial infarct extension: incidence and relationship to survival
JT Baker, DA Bramlet, RM Lester, DG Harrison, CR Roe and FR Cobb
Myocardial infarct extension, defined as reelevation or reappearance of
creatine phosphokinase-MB (CK-MB) 48 hours after the onset of symptoms, was
evaluated prospectively in 56 consecutive patients with acute myocardial
infarction. Myocardial infarct extension occurred in eight patients (14%).
The sensitivity, specificity and predictive accuracy in the diagnosis of
myocardial infarct extension were 63%, 85% and 42%, respectively, for
recurrent chest pain requiring morphine; 50%, 65% and 19% for recurrent
ST-segment elevation on routine 12-lead ECGs; and 88%, 63% and 28% for
reelevation of total CK. Three of the eight episodes of extension were
clinically silent. Four of eight patients (50%) with extension died,
compared with one of 46 patients (2%) without extension (p = 0.0009). CK-MB
persisted for 72 hours or longer in 16 patients and identified seven of
eight patients who subsequently had infarct extension. We conclude that
myocardial infarct extension is an infrequent complication of acute
myocardial infarction and is associated with a very high mortality rate.
Persistence of CK-MB for 72 hours or more identifies a subgroup of patients
at high risk for subsequent infarct extension and death.