Imagining
Measurement
Echocardiography, nuclear, CMR
Anatomic position
Measurement
LV lead to latest activation site determined using imaging
Timing
Measurement
Greatest delay from onset of QRS to local LV electrogram
Contractility
Measurement
Acute increase in dP/dtmax or pulse pressure (systolic minus diastolic blood pressure)

CMR, cardiac magnetic resonance; LV, left ventricular; RV, right ventricular.