[Precordial mapping of the QRS complex and Frank's orthogonal ECG in evaluation of the myocardial infarct area. Comparison of the 2 methods].

Precordial mapping of QRS complex is a reliable tool in attempts to quantitate infarct size in patients with acute myocardial infarction. However the recording of multiple precordial leads is an expansive and time-consuming process; the purpose of this study is to investigate the usefulness of Frank's ECG as a substitutive method of infarct sizing. In a group of patients with acute myocardial infarction of the anterior wall many repeated precordial mappings with simultaneous recording of x, y, z leads of Frank's ecg were obtained (71 observations as a whole). Parameters provided by precordial mapping [delta R, delta Q, delta R + delta Q, delta R/delta (Q + S)] and by Frank's ecg (spatial vector voltage deviation of QRS or VSDV-QRS; spatial vector area deviation of QRS or VSDA-QRS; spatial vector R wave deviation or VSDR) were correlated each other by means of linear regression analysis. delta R + delta Q correlated significantly with VSDA QRS (r = 0.54; p less than 0.001) and with VSDR (r = 0.55; p less than 0.001) as regards the total of observations. The correlation coefficient was higher (r = 0.8; p less than 0.001) if comparison between delta R + delta Q and VSDA-QRS was restricted to early 48 hours from the beginning of the symptoms. This could be explained by the greater entity of QRS complex changes in this period, compared to the subsequent course. We conclude that Frank's ecg is an useful alternative method to precordial mapping in sizing the extension of myocardial necrosis.