The Relationship of Alterations in Systolic Time Intervals to Ejection Fraction in Patients with Cardiac Disease

The relationships between the systolic time intervals determined from simultaneous recordings of the electrocardiogram, the phonocardiogram, the carotid arterial pulse tracing, and direct measures of left ventricular performance as assessed angiographically by measurement of left ventricular stroke volume (SV), end-diastolic volume (EDV), and ejection fraction (EF) were studied in 68 patients with a wide variety of cardiac diseases. The systolic intervals, the pre-ejection period (PEP), the left ventricular ejection time (LVET), and the ratio PEP/LVET, each correlated significantly with angiographically determined EF and EDV. Closest correlation was observed between PEP/LVET and EF (r = -0.90). The systolic intervals correlated only slightly with the angiographically determined SV. These data lend additional evidence supporting the use of systolic time intervals as a non-invasive measure of left ventricular performance in patients with cardiac disease.