BACKGROUND: The first derivative of left ventricular (LV) pressure over time (dP/dt max) is a marker of LV systolic function that can be assessed during cardiac catheterization and echocardiography. Radial artery dP/dt max has been proposed as a possible marker of LV systolic function and we sought to test this hypothesis. MATERIALS AND METHODS: We compared simultaneously recorded radial dP/dt max (by high-fidelity tonometry) with LV dP/dt max (by high-fidelity catheter and echocardiography parameters analogous to LV dP/dt max). In study 1, beat-to-beat radial dP/dt max and LV dP/dt max were recorded at rest and during supine exercise in 12 males (aged 61 +/- 12 years) undergoing cardiac catheterization. In study 2, 2D-echocardiography and radial dP/dt max were recorded in 54 patients (separate to study 1; 39 men; aged 64 +/- 10 years) at baseline and peak dobutamine-induced stress. Three basal septum measures were taken as being analogous to LV dP/dt max: 1. Peak systolic strain rate; 2. Strain rate (SR-dP/dt max) during isovolumic contraction (IVCT) and; 3. Tissue velocity during IVCT. RESULTS: In study 1 there was a significant difference between resting LV dP/dt max (1461 +/- 383 mmHg s(-1)) and radial dP/dt max (1182 +/- 319 mmHg s(-1); P < 0.001), and a poor, but statistically significant, correlation between the variables (R(2) = 0.006; P < 0.05). Similar results were observed during exercise. In study 2 there were weak (R(2) = -0.12; P = 0.01) to non-significant associations between radial dP/dt max and all echocardiographic measures analogous to LV dP/dt max at rest or peak stress. CONCLUSION: Radial pressure waveform dP/dt max is not a reliable marker of LV systolic function.