Influence of left ventricular cavity dimension on electrocardiographic estimation of the extent of wall motion abnormalities.

To estimate the influence of left ventricular cavity dimension on the electrocardiographic estimation of the extent of wall motion abnormalities, two-dimensional echocardiograms and standard 12-lead electrocardiograms (ECG) were carried out on 221 patients within 3 months after acute myocardial infarction (MI). Among the patients with anterior MI (96 patients; 43.4%) both the extent of asynergy (% of asynergic segments, an echo index taking into account the type of asynergy) and the electrocardiographic signs of necrosis (number of Q waves greater than or equal to 40 ms, Wagner's score) were significantly greater (p less than 0.001) in those with left ventricular dilatation (60 patients) than in those with normal ventricular size (36 patients); within the latter group, the ECG-asynergy correlations were good (r value 0.67-0.79). In patients with left ventricular dilatation no correlation was found. In inferior MI (108 patients, 48.9%), asynergy was more extensive in patients with left ventricular dilatation (p less than 0.001) than in those with normal left ventricle. However, the electrocardiographic extent of necrosis was similar in the two groups and no significant ECG-asynergy correlation was found. Likewise, in anteroinferior MI (17 patients; 7.7%), the ECG-asynergy correlations were statistically insignificant in both groups. In conclusion, the electrocardiographic patterns of necrosis are poorly related to the extent of asynergy and are greatly influenced by left ventricular dimensions.