Background: Circulatory biomechanics dictate that, with given arterial compliance and pulse pressure, left ventricular ejection and isovolumic-contraction durations (T_ej and T_ic) reflect systolic ventricular function. Cardiovascular risk assessment, therefore, may benefit from accessible and reproducible measurement of these systolic time intervals (STI). We recently developed a tool to extract STI from carotid artery distension waveforms. We used it here to investigate whether systolic ventricular function is different in patients requiring chronic beta-blockade (BB) compared to controls.

Methods and Results: In 81 patients on BB and 87 age- (61±7yrs) and sex-matched untreated controls, we obtained untreated STI and blood pressures. BB patients discontinued medication 1 day prior to measurements. Intra-session coefficients of variation for T_ej and T_ic were 0.8% and 6.8%; and inter-session 2.7% and 8.4% (i.e. 100%·SD_intra/inter/mean).

T_ej and pulse pressure (PP), thus the PP·T_ej product reflecting ventricular stroke work, were significantly greater in (untreated) BB patients (all p<0.002). T_ic was not different between the groups. The T_ic/ T_ej ratio was smaller for the BB group (p=0.04), indicating increased systolic ventricular function, likely matching the greater stroke work required.

Conclusions: Patients requiring chronic beta-blockade have longer ventricular ejection periods combined with greater pulse pressures, indicating greater ventricular stroke work and thus enhanced systolic function. Our findings readily demonstrate the accessibility and reproducibility of non-invasive STI measurement in a clinical population.