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E/e' Ratio
The ratio of early diastolic mitral inflow velocity (E) to early diastolic mitral annular tissue velocity (e'). A non-invasive surrogate for LV filling pressure.
E/e' combines two Doppler measurements: E (pulsed-wave Doppler at the mitral valve tips) and e' (tissue Doppler at the mitral annulus, septal or lateral). The ratio reflects left-ventricular filling pressure non-invasively.
Average E/e' >14 is consistent with elevated left-atrial pressure (ASE / EACVI 2016) and is one of the four structural / functional pillars of HFpEF diagnosis.
E/e' measurement requires accurate sampling at the correct anatomic location, septal vs lateral matters. AI-assisted measurement standardises sampling location and angle correction.