Purpose:Diastolic waveforms in the left ventricular outflow tract (LVOT) are commonly observed with Doppler echocardiography.The incidence and mechanism are not well described.Methods:This was a retrospective observational study of 186 adult patients, athletes and non-athletes, free of known cardiacdisease, presenting for comprehensive transthoracic echocardiography at a research institute. We aimed to evaluate the incidenceand echocardiographic associations between LVOT diastolic waveforms.Results:Left ventricular outflow tract early to mid-diastolic waveforms were present in 100% of athletes and 95% of non-athletes. The LVOT diastolic velocity time integral was larger in athletes than non-athletes with a mean 8.3 cm (95% CI (7.6–8.9))vs. 5.1 cm (4.4–5.9) (P<0.0001). Multivariate predictors of this diastolic waveform were age (P=0.002), slower heart rate(P=0.035), higher stroke volume (P=0.003), large mitral E (P=0.019) and higher E/e’ (P=0.015).Discussion:An LVOT early diastolic wave is a normal physiological finding. It is related to a flow vortex redirecting diastolic mitralinflow around anterior mitral valve leaflet into the LVOT.Conclusions:Early to mid-diastolic LVOT waves are present in almost all patients but more prominent in young athletes than non-athletes. Diastolic LVOT waves increase with younger age, slower heart rate, larger stroke volume and enhanced diastolicfunction.Keywords:diastole, echocardiography, haemodynamics, stroke volume, transthoracic.