Detection of left ventricular systolic dysfunction using a newly developed, laptop based, impedance cardiographic index

Congestive heart failure (CHF) is a major cause of morbidity and mortality worldwide [1]. The development of left ventricular systolic dysfunction (LVSD) is a marker of poor prognosis. Mild reduction in EF progresses with time and when EF gets to b40%, most patients develop CHF and their prognosis is dismal [2,3]. Simple, cheap techniques that will reliably detect mild reduction of the EF, typical for ALVSD,will thus be of enormous value to reduce the occurrence of CHF and cardiac mortality [3–7]. Impedance Cardiography (ICG) is a noninvasive method of determining hemodynamic status and reliable estimates of myocardial contractility (and EF) can be obtained using indices based on systolic time intervals [8–10]. We have recently developed an index— Granov Goor Index (GGI)—that combines time interval and impedance parameters in order to identify subjects with LVSD. The GGI is obtained from a regional ICG signal—measured using wrist and ankle electrodes [10–13]. In this manuscript we determined the accuracy of GGI in identifying subjects with LVSD (in a “training” cohort of 100 individuals) and validated the findings in an additional cohort of 201 subjects. The regional ICG signal is obtained from 2 pairs of tetra-polar electrodes: one on the wrist, above the radial artery, and the other on the contra-lateral ankle above the posterior tibial artery. The detailed description of the system and measured parameters can be reviewed in previous publications [10–13]. The GGI is designed to assess the systolic contractile function of the LV and is obtained from the following formula: