[Significance of the size of an acute infarct for left ventricular haemodynamics (author's transl)].

Acute infarct size was estimated from serial determinations of creatine-kinase (CK) activity. In 15 patients the infarct size was obtained post-mortem, using nitro-blue-tetrazolium stain. There was good correlation between the two measurements (r = 0.98). The relationship between the calculated infarct size and haemodynamic values was obtained in 50 patients (end-diastolic pulmonary arterial pressure [PAEDP], cardiac output, stroke volume, stroke volume/filling pressure of left ventricle [SVI/PAEDP]). On average there was a tendency towards impaired left ventricular haemodynamics with increasing infarct size. Among the survivors the infarct size (51 g) was significantly less (P less than 0.05) than that of those who had died (83 g). PAEDP at 24 mm Hg was significantly higher in those who died than in the survivors (17 mm Hg), cardiac index was 2.95 l/min-m2 in the survivors compared with 2.14 l/min-m2, while SVI/PAEDP was 2.4 ml/m2-mm Hg in the former and 0.9 ml/m2-mm Hg in the latter. However, in individual cases the infarct size sometimes did not correlate with haemodynamic values. Taking into account infarct size and haemodynamics, four classes could be distinguished: (a) infarct size less than 65 g with good haemodynamics (PAEDP less than 18 mm Hg, normal cardiac index); (b) infarct size greater than 65 g with PAEDP greater than 18 mm Hg and markedly reduced cardiac index). Only 10% of those a to c had previously had infarcts, compared with 60% of those in class d (infarct less than 65 g, PAEDP above 18 mm Hg). Small infarcts with markedly impaired haemodynamics thus indicate that there has been previous damage to remaining myocardium.