Quantitative and temporal relation between the release of myoglobin and creatine kinase and the evolution of...

The relation in time and magnitude between QRS vector changes (QRS-VD), ST vectors (ST-VM), and the cumulated release of myoglobin, total creatine kinase, and creatine kinase isoenzyme MB was studied. Seventy four patients with a first myocardial infarction and a history of symptoms of up to 5 h were included. Blood samples for enzyme analysis were taken every 4-6 h for 72 h and cumulated enzyme release was calculated from a monocompartmental first order model. QRS-VD and ST-VM were determined every 10 min for 24 h by computer analysis of Frank lead vectorcardiograms. Infarct sizes were visually determined from the different enzymatic and vectorcardiographic evolution curves. Eight patients were excluded from the analysis because they had a QRS width greater than or equal to 120 ms or ill defined plateaus of the release curves. The relation between infarct sizes estimated from QRS-VD and total creatine kinase was r = 0.62; QRS-VD and myoglobin release r = 0.57; total creatine kinase and myoglobin release r = 0.72, showing that these variables are good and complementary indices for estimating myocardial infarct size. Median infarct evolution curves were computed after the individual curves were normalised to 100%. ST-VM fell rapidly during the first 7 h to 40% of the initial values. QRS-VD and myoglobin release were closely associated and completed their development on average 15 h after the onset of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)