Usefulness of electrocardiographic findings and creatine kinase levels on admission in predicting the accuracy of the interval between onset of chest pain of acute myocardial infarction and initiation of thrombolytic therapy.
Patients with chest pain lasting greater than 6 hours and suggesting acute myocardial infarction (AMI) are often excluded from thrombolytic therapy, because myocardial necrosis is believed to be largely irreversible beyond that time. To evaluate the relation between time of onset of chest pain and enzymatic evidence of myocardial necrosis, enzymes on admission were analyzed in 221 consecutive patients with greater than or equal to 2 mm ST-segment elevation by electrocardiography on admission and no contraindications to thrombolytic therapy. Patients with symptoms within 6 hours (n = 170, early) received thrombolytic therapy, but those with symptoms after 6 hours did not (n = 51, late). Eventually, 219 (168 early, 51 late) patients had enzymatically proven AMI within 24 hours. Creatine kinase levels on admission less than twice the upper normal limit were found in 155 (91%) early patients, but surprisingly, also in 30 (59%) late patients. By electrocardiography on admission, ST-segment elevation per lead was 2.1 +/- 1.1 mm in late patients with low initial enzymes versus 1.1 +/- 0.3 mm in those with elevated initial enzymes (p less than 0.0001). Concomitantly, Q waves in leads with ST-segment elevation were present in 17 (57%) late patients with low enzymes on admission versus 17 (81%) with elevated enzymes on admission (p = 0.06). Eventually, maximal creatine kinase levels were similar in all late patients irrespective of enzyme levels on admission. Therefore, many patients with symptoms of AMI after 6 hours have low enzymes on admission and may still be eligible for thrombolytic therapy.(ABSTRACT TRUNCATED AT 250 WORDS)
Beek
A M
AM
Department of Cardiology, Free University Hospital, Amsterdam, The Netherlands.
Verheugt
F W
FW
Meyer
A
A
D000368:Aged; D004796:Clinical Enzyme Tests; D003402:Creatine Kinase / Q000097:blood*; D004562:Electrocardiography; D004608:Eligibility Determination; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy / Q000453:epidemiology; D009206:Myocardium / Q000473:pathology; D015203:Reproducibility of Results; D015912:Thrombolytic Therapy; D013997:Time Factors
D003402:Creatine Kinase