Clinical assessment of infarct size by serial determinations of serum creatine phosphokinase activity.

Infarct size (IS) was estimated from serial total creatine phosphokinase (CK) changes in 82 patients with acute myocardial infarction (MI). Anteroseptal and inferior MI involved a relatively small mass of myocardium (16.0 +/- 6.4 and 24.7 +/- 10.0 CK-g-eq respectively); anteroapical and inferoposterior MI had an average IS of 35.9 +/- 15.9 and 32.8 +/- 13.8 CK-g-eq respectively (NS); extensive anterior and inferoposterolateral MI had an average IS of 57.8 +/- 20.1 and 51.1 +/- 11.5 CK-g-eq respectively (NS). Left ventricular failure (LVF) correlated with estimated IS and not with location of the infarct. In patients with an IS ranging from 30 to 50 CK-g-eq, the incidence of LVF was 33%. In patients with an IS greater than 50 CK-g-eq, the incidence of LVF was 65%. Out of the 6 patients who died, 3 had an IS greater than 60 CK-g-eq. 3 groups of patients could be identified from the duration of the CK release time: in group I (mean = 20 +/l h; n = 61), infarct size was highly correlated with peak CK activity (r = 0.93); in group II (mean = 39 +/- 7 h; n = 17) the correlation between IS and peak CK activity was poor (r = 0.59) and might indicate a gradual necrosis; in group III (n = 4) patients with reinfarction showed a second peak on the descending limb of the CK activity curve. Follow-up information was available in 96% of the 76 survivors. At the end of the follow-up (18.1 +/- 10.8 mth) IS was not significantly different in patients with LVF (42.7 +/- 17.5 CK-g-eq) and in those without LVF (34.7 +/- 19.7 CK-g-eq).