Comparison of enzymatic, anatomic and electrocardiographic estimates of myocardial infarct size in man.

Myocardial infarct size is definitely related to cardiac function and prognosis. For a critical evaluation of infarct size estimation methods, we weighed infarcted myocardium from 44 autopsy cases (24 men and 20 women, mean age of 76.8 yr.), and compared the weight with the peak value of serum CPK activity (peak-CPK), the peak value of serum CPKMB isoenzyme activity (peak-CPKMB), the total CPK release (sigma CPK), and the QRS scoring system in the standard 12-lead electrocardiogram (ECG) modified by Wagner et al.. The mean infarcted myocardial weight (MI weight) of the 44 cases was 38.4 g. The mean value of the peak-CPK, peak-CPKMB, and sigma CPK were 2487, 221, and 4597 IU/ml, respectively, and the mean QRS point score was 7.2. The interval between serial CPK determination and ECG recording or autopsy averaged 130.1 or 52.4 days, respectively. There were significant (p less than 0.01) correlations between the MI weight and peak-CPK (r = 0.63, n = 17), peak-CPKMB (r = 0.79, n = 17), sigma CPK (r = 0.72, n = 11), and the QRS scoring system (r = 0.64, n = 39), respectively. Especially in cases of non-transmural myocardial infarction, the QRS scoring system showed a high correlation with MI weight (r = 0.82, n = 11, p less than 0.01). We conclude that the peak-CPK, peak-CPKMB, sigma CPK, and the QRS scoring system are useful for the estimation of myocardial infarct size.