Early post-stress decrease in cardiac performance by impedance cardiography and its relationship to the severity and extent of ischemia by myocardial perfusion imaging.

BACKGROUND While single photon emission computed tomography (SPECT) myocardial perfusion imaging (MPI) is a well-established noninvasive procedure for the evaluation of patients with coronary artery disease (CAD), it is unable to detect the presence of, or underestimates the extent of CAD in certain patients. We aimed to show that a bio-impedance device can detect early post-stress changes in several hemodynamic parameters, thereby serving as a potential marker for the presence of significant ischemia. METHODS Prospectively enrolled patients, referred to our Medical Center for clinically-indicated MPI, underwent testing using a Non-Invasive Cardiac System (NICaS) before and immediately after exercise. The differences between rest and stress hemodynamic parameters were compared with the severity and extent of myocardial ischemia by MPI. The study included 198 patients; mean age was 62 years, 26% were women, 54% had hypertension, and 29% diabetes mellitus. Of them, 188 patients had ≤10%, and 10 had > 10% of myocardial ischemia. RESULTS In the first group, there was a significantly greater increase in post-exercise stroke index, stroke work index, cardiac index and cardiac power index (19.2, 29.1, 90.5 and 107%, respectively) compared with the second group (- 2.7, 3.8, 43.7 and 53.5%, respectively), as well as a significantly greater decrease in total peripheral resistance index (- 38.7% compared with - 16.3%), with corresponding p values of 0.015, 0.017, 0.040, 0.016, and < 0.001, respectively. CONCLUSIONS Our data suggest that immediate post-stress changes in several hemodynamic parameters, detected by the NICaS, can be used as an important adjunct to SPECT MPI for the early detection of myocardial ischemia.