This prospective study had two aims, to study the Doppler parameters of left ventricular systolic function with respect to heart rate, and to determine the influence of ischaemic heart disease on these variations. The Doppler indices (velocity time integral, maximum velocity and average acceleration of systolic flow in the left ventricular outflow tract) were measured and averaged over 3 beats after digitization: the measurements were repeated in 30 patients under basal conditions and after 2 minutes transoesophageal atrial pacing at 150 beats/min. These 30 patients were divided into 3 groups: group 1 control subjects with normal coronary arteries, n = 13, EF = 71 +/- 8.9%; group 2 coronary patients without myocardial infarction (greater than 70% stenosis on coronary angiography), n = 9, EF = 64.3 +/- 10.3%; group 3, coronary patients with previous infarction, n = 8, EF = 51.8 +/- 10.9% (p less than 0.0006). Variance analysis for repeated measurements showed significant decreases in velocity time integrals and maximum velocities after pacing (11.8% +/- 2.2 and 0.86 +/- 0.1 versus 18.3 +/- 2.2 and 0.91 +/- 0.1, p less than 0.0001 and p less than 0.05 respectively). This decrease was identical in the three groups. The variations observed were therefore related to the increase in heart rate and not to coronary status or left ventricular function.