Here is a link to the full text of the article in Annals of EM

It is critical to use it only when the differential is subtle LAD occlusion vs. early repol. If there is LVH, it may not apply. If there are features that make LAD occlusion obvious (inferior or anterior ST depression, convexity, terminal QRS distortion, Q-waves), then the equation MAY NOT apply. These kinds of cases were excluded from the study as obvious anterior STEMI. ST elevation (STE) is measured at 60 milliseconds after the J-point, relative to the PR segment, in millimeters.

(1.196 x STE at 60 ms after the J-point in V3 in mm) + (0.059 x computerized QTc) – (0.326 x R-wave Amplitude in V4 in mm).

Use the calculator below. A value greater than 23.4 is quite sensitive and specific for LAD occlusion.