Clinical significance of "reciprocal" S-T segment depression in acute myocardial infarction. Relative contributions of infarct size and ischemia at a distance.
The early electrocardiographic results in 100 patients surviving their first myocardial infarction who thereafter underwent serial radionuclide ventriculography were reviewed. Site of infarction was anterior in 46 and inferior in 54, with lateral extension in two patients. Those with "reciprocal" S-T segment depression of more than 1 mm in the acute phase (n = 53) sustained larger infarcts on the basis of enzyme criteria (mean peak serum creatine kinase, +/- SD, 2,203 +/- 1,271 versus 1,544 +/- 1,197 IU/liter, p less than 0.02), with a higher incidence of ventricular akinesis and dyskinesis. Reciprocal change was more common during inferior infarction (n = 33) than anterior infarction (n = 20). Despite equivalent peak enzyme levels following anterior and inferior infarction with reciprocal S-T depression (mean peak creatine kinase 2,330 versus 2,128, NS), there was marked sparing of left ventricular function in the latter group (mean left ventricular ejection fraction 0.31 +/- 0.14 versus 0.42 +/- 0.09, p less than 0.01). Of 17 patients who died within two years of infarction, 14 had reciprocal changes. Patients who died after anterior infarction with reciprocal changes (n = 5) had poor left ventricular function compared with those who died after inferior infarction (n = 9; left ventricular ejection fraction, +/- SD, 0.21 +/- 0.05 versus 0.38 +/- 0.11, p less than 0.01). One third of those recovering from inferior infarction with reciprocal changes subsequently had positive results on exercise testing, and of the nine patients who died, five had good left ventricular function (left ventricular ejection fraction 0.44 to 0.50). Infarct size and ventricular wall motion abnormality proved to be of major importance in the production of inferior reciprocal S-T change during anterior infarction, and subsequent mortality was related to poor left ventricular function. The proximity of the precordial leads to left ventricular myocardium may increase the detection of concomitant anterior ischemia during inferior infarction, and those who exhibit reciprocal change are presumably at risk from left main stem or anterior descending lesions but with reasonably good ventricular function represent a more attractive population for invasive investigation.
D003402:Creatine Kinase / Q000097:blood; D004562:Electrocardiography / Q000295:instrumentation; D004566:Electrodes; D005080:Exercise Test; D005260:Female; D005500:Follow-Up Studies; D006352:Heart Ventricles / Q000000981:diagnostic imaging; D006801:Humans; D008297:Male; D009203:Myocardial Infarction / Q000000981:diagnostic imaging / Q000503:physiopathology*; D005082:Physical Exertion; D011379:Prognosis; D011877:Radionuclide Imaging; D013997:Time Factors
D003402:Creatine Kinase