Table 1.

Definitions for selected ECG measurements

ECG Measurement	Operational Definition
PR, QRS, QT, QTc intervals	Automated values after manual verification
Frontal plane axis (P, QRS, T)	Automated values after manual verification
Atrial or ventricular premature beats	Present/not present
Right intraventricular conduction delay	RSR' pattern in V1 with QRS 100–119 ms
Right bundle branch block (RBBB)	RSR’ pattern in V1 with a QRS duration ≥120 ms
Left intraventricular conduction delay	QS or rS pattern in V1 with a QRS duration 100–120 ms
Left bundle branch block (LBBB)	QS or rS pattern in V1 with a QRS duration >120 ms.
Anterior fascicular block	Left axis deviation with qR in aVL and onset to peak R ≥45 ms.
Posterior fascicular block	Right axis deviation with rS in I, aVL, and qR in III, aVF
Left atrial enlargement	Biphasic P wave in V1 with a large terminal negative component whose area ≥40 ms by −0.1 mV; or, notched P wave in II with inter-peak interval >40 ms
Right atrial enlargement	P wave amplitude in V1 or V2 ≥0.15 mV
Left ventricular hypertrophy	Sum of S wave in V1 + R in V5 or V6 ≥3.5 mV or R in aVL ≥0.9 mV for women or ≥1.1 mV for men
Right ventricular hypertrophy	Right axis deviation and R/S ratio in V1 ≥1
ST elevation (2 contiguous leads)	J-point ST elevation with cutoff points in V2, V3 of ≥0.2 mV in men ≥40 years; ≥0.25 mV in men <40 years; ≥0.15 mV in women.
ST depression, T inversion (2 contiguous leads)	Horizontal or down-sloping ST depression of ≥0.05 mV and/or T wave inversion of ≥0.1 mV

ms = millisecond; mV = millivolt