Uncorrected pre-ejection period: a simple non-invasive measurement for pharmacodynamic screening of inotropic activity.

Since heart rate (HR) is an important determinant of the duration of systole, systolic time intervals (STI) from 8 healthy subjects were examined after infusion of atropine. As no overall correlation was found between HR and pre-ejection period (PEP), the results confirm the need for individual estimates of the correction of the left ventricular ejection time (LVET) and the total electromechanical systole (OS2). In the same subjects the sensitivity of PEP to minor negative inotropic effects of mexiletine and disopyramide measured at Cmax was confirmed. Thus, in addition to its simplicity and reliability, the sensitivity of the uncorrected PEP should encourage use of this technique as part of any screening system for the early detection of an inotropic effect of new chemical entities.