Frequency and significance of late evolution of Q waves in patients with initial non-Q-wave acute myocardial infarction. Diltiazem Reinfarction Study Group.
Serial 12-lead electrocardiogram and plasma creatine kinase (CK)-MB values from 544 patients with confirmed non-Q-wave acute myocardial infarction (AMI) were analyzed to define the rate of progression of non-Q-wave AMI to Q-wave AMI and to examine its relation to CK-MB evidence of extension. The baseline electrocardiogram was obtained 50 +/- 10 hours after AMI and compared with subsequent electrocardiograms at 48 and 72 hours after baseline record and at discharge. Plasma CK-MB was assayed every 12 hours after baseline. A total of 76 patients (14%) progressed to Q-wave AMI. Compared to the 468 patients who retained non-Q-wave AMI, those patients who evolved Q-wave AMI were more likely to exhibit ST elevation greater than or equal to 1.0 mm in greater than or equal to 2 infarct-related leads (49 vs 32%, p less than 0.005), higher peak CK values with the index AMI (754 +/- 625 vs 611 +/- 604 IU; p = 0.0018) and a greater incidence of CK-MB-confirmed extensions (18.5 vs 5.5%, p less than 0.0001). For those patients progressing to Q-wave AMI within 48 hours of baseline electrocardiogram, CK-MB extension occurred in 9.5% (4 of 42) versus 29.4% (10 of 34) of those who progressed after 48 hours (p = 0.0262). A distinct minority (14%) of patients with non-Q-wave AMI will develop Q waves before discharge. The progression to Q-wave AMI after initial non-Q-wave AMI appears to involve 2 different mechanisms: temporal lag in the electrocardiogram, and actual extension by quantitative CK-MB criteria.
Division of Cardiology, Jewish Hospital, Washington University, St. Louis, Missouri 63110.
R E
RE
Kleiger
W E
WE
Boden
K B
KB
Schechtman
R S
RS
Gibson
D J
DJ
Schwartz
B J
BJ
Geiger
R J
RJ
Capone
R
R
Roberts
D003402:Creatine Kinase / Q000097:blood; D004110:Diltiazem / Q000627:therapeutic use; D004562:Electrocardiography; D006801:Humans; D007527:Isoenzymes; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000188:drug therapy; D016032:Randomized Controlled Trials as Topic; D013997:Time Factors
D007527:Isoenzymes; D003402:Creatine Kinase; D004110:Diltiazem