Patient selection: ST segment elevation
Parameters:
(1) T wave amplitudes in V1, V2, V3, V4 in mm based on positive portion of the T wave
(2) QRS complex amplitudes in V1, V2, V3 and V4 in mm based on the absolute value for the distance from nadir of Q, S or QS wave to peak of the R wave
sum of T wave amplitudes =
= SUM(amplitudes of the T waves in the 4 leads)
sum of QRS complex amplitudes =
= SUM(amplitudes of the QRS in the 4 leads)
ratio of sums for T wave and QRS complexes =
= SUM(T wave amplitudes) / SUM(QRS complex amplitudes)
ratio of T wave to QRS complex amplitudes in a particular lead =
= (T wave amplitude) / (QRS complex amplitude)
Rule 1: Acute STEMI is present if the ratio of the sums of the T waves and QRS complexes is > 0.22
Rule 2: Acute STEMI is present if any one of the ratio of T wave to QRS complex amplitudes is >= 0.36
Performance:
• Rule 1 had a sensitivity of 92-95%, specificity of 70-91% and accuracy of 87-93%.
• Rule 2 had a sensitivity of 92-95%, specificity of 81-82%% and accuracy of 89-90%.
