Assessment of myocardial infarct size in clinical practice.

The myocardial infarct size was assessed on the basis of serial analyses of serum creatine phosphokinase (CPK) in 70 patients with first transmural myocardial infarction. Clinical symptoms of heart failure (Killip II-III) were found in patients with infarcts larger than 50 CPK-g-equ; in patients with lung oedema the infarct size averaged 104.2 CPK-g-equ. Patients without clinical and roentgenological evidence of left heart failure (Killip I) had infarct sizes always lesser than 50 CPK-g-equ, averaging 31.7 CPK-g-equ. Precordial mapping of the QRS complex in patients with anterior wall infarction revealed a significant correlation (r = 0.916) between the sum of voltages of Q waves on a 30-lead map recorded 24 hours after hospitalization and the enzymically assessed infarct size. Exact skiagraphic and auscultatory examinations of the heart and lungs, together with precordial mapping of the QRS complex, in patients with anterior wall infarct allow a relatively accurate quantification of the infarct size for prognostic classification of the patients.