Change in angular velocity at the end of the QRS loop aids the electrocardiographic detection of acute inferior myocardial infarction

We developed a new method for determining the QRS end, based on angular velocity (AV) changes around the QRS loop, and compared the method´s performance to that of more established methods for determining QRS end in both healthy subjects and patients with acute myocardial infarction (AMI). Specifically, using Frank leads reconstructed from standard 12-lead ECGs, we determined AV in the direction of change raised to the 4th power, d(t). We found that the d(t)-determined AV transition (AVTr) nearly coincided with manually determined QRS end in healthy subjects, and in 27 patients with anterior AMI. However, in 31 patients with inferior AMI, AVTr typically preceded that of QRS end determined by the established methods, and by more than 10 ms in 32% of cases. While this “AVTr precedence” coincided with diagnostic ST elevation in only a minority of patients with recent inferior AMI, the use of AVTr precedence as a complement to more established methods for QRS end determination increased the sensitivity for detecting inferior AMIs from 23% to 42% without notably compromising specificity in healthy subjects (N=1050).