Infarct size estimated from serial serum creatine phosphokinase in relation to left ventricular hemodynamics.

Abstract

In 50 patients with proven acute myocardial infarction (AMI), left ventricular hemodynamics (pulmonary end-diastolic pressure [PAEDP]; cardiac index [CI]; stroke volume index [SVI]; and SVI/PAEDP were related to the size of the acute infarct. Acute infarct mass was calculated from serial determinations of serum creatine phosphokinase (CPK) every two hours, using a computer program. In 15 cases postmortem measurement of acute infarct size after staining with Nitro-BT was made and correlated with calculated infarct size. Correlation in this limited number of cases was good with a mean difference of 7 g. Acute infarct mass in 38 survivors was 46 +/- 5 g and was significantly smaller (P less than 0.05) than in the 12 nonsurvivors (76 +/- 12 g.) PAEDP in surviving patients was significantly lower (17 +/- 1 mm Hg) and SVI (36 ml/m2) and SVI/PAEDP (2.4 ml/m2/mm Hg) significantly higher than in the nonsurvivors (PAEDP: 24 mm Hg; SVI: 23 ml/m2; SVI/PAEDP: 0.86 ml/m2/mm Hg) (P less than 0.001 for all differences). Similar significant differences were observed between patients not in shock and those in cardiogenic shock. Although in 39 patients, in whom the infarction was their first, infarct mass was larger (58 +/- 6 g) than in 11 patients with repeat infarctions (37 +/- 8 g), left ventricular hemodynamics were slightly more impaired in reinfarctions (PAEDP: 21 +/- 3 mm Hg; CI:2.60 L/min/m2) than in first infarctions (PAEDP: 18 +/- 1 mm Hg; CI:2.82 L/min/m2). The occurrence of cardiogenic shock was a strong predictor of death; however, the wide scatter of the data for the parameters cardiac index, PAEDP, and acute acute infarct mass precluded their usefulness, when taken individually, in predicting survival. When a relationship between hemodynamics and infarct size was looked for, four constellations of individual patients were identified. These groups were defined by PAEDPs of above or below 18 mm Hg and infarct sizes above or below 65 g. Class A patients (N = 22) had a small infarct (29 +/- 4 g) and good pump function (PAEDP: 13 mm Hg; SVI: 40 ml/m2; SVI/PAEDP: 3.27 ml/m2/mm Hg); prognosis was good for these patients. In class B (N = 13) the infarct was large (96 +/- 8 g) and pump function markedly impaired (PAEDP: 26 mm Hg; SVI: 24 ml/m2; SVI/PAEDP: 0.98 ml/m2/mm Hg); 54% of these patients died. Five patients in class C had, in the presence of a large infarct (84 g), only a slightly elevated PAEDP of 17 mm Hg and an almost normal SVI of 37 ml/m2. In contrast, the ten class D patients had an infarct size (34 g) similar to that in class A, but high PAEDP (23 mm Hg) and moderately reduced SVI (31 ml/m2). In this group a high incidence of reinfarctions (six out of ten) occurred. It is concluded that infarct mass calculated from serial CPK analysis, as a single parameter, cannot be used to predict mortality or development of cardiogenic shock in an individual patient.