Increasing precordial QRS voltage correlates with improvement in left ventricular function following anterior myocardial infarction.

To evaluate whether changes in QRS voltage reflect changes in left ventricular function after myocardial infarction, 28 patients were studied following anterior myocardial infarction. Two-dimensional echocardiograms and 12-lead electrocardiograms were obtained during the acute phase of the infarction and again after at least 30 days of recovery (mean, 8 +/- 8 months). At follow-up, 11 patients (group A) showed improvement in left ventricular systolic function; 9 had increased net QRS voltage in V1-6 and 8 in V1-4. No improvement in ventricular function was found in 17 patients (group B); 7 had increased QRS voltage in V1-6 (p less than 0.05 vs group A) and only 5 in V1-4 (p less than 0.05 vs group A). For detection of improved left ventricular function, the sensitivity, specificity, and predictive value of the change in net QRS voltage for leads V1-6 was 82%, 59%, and 56% respectively, and for leads V1-4 was 73%, 71%, and 62% respectively. Neither R wave voltage, Q wave voltage, nor the total number of Q waves was reliable for identifying patients with improving left ventricular function. Thus, increasing net QRS voltage in the precordial electrocardiographic leads during long-term follow-up after anterior myocardial infarction correlates with and has a reasonable sensitivity for detection of improvement in left ventricular systolic performance.