Hemodynamic differences among hypertensive patients with and without heart failure using impedance cardiography

Impedance cardiography is a reliable, well-tolerated, and non-invasive method used to obtain hemodynamic measurements and could potentially be useful in heart failure (HF) diagnosis, hemodynamic monitoring of critically ill patients, and help in the choice of antihypertensive therapy. The objective of this study was to determine the differences between hemodynamic parameters in a study population of hypertensive patients with and without HF, using impedance cardiography.

A case-control study was designed and named the TARGET study. Participants were enrolled in two study groups: control group C, hypertensive patients without HF and the HF group, hypertensive patients with HF. A descriptive analysis was carried out to characterize the sample and differences in continuous variables were tested for statistical significance by independent sample t test.

The study included 102 hypertensive outpatients. The control group consisted of 77 individuals (58.4% males; mean age 63.9 ± 12.5 years old) and the HF group consisted of 25 individuals (44.0% males; mean age 74.2 ± 8.7 years old). The mean Cardiac Index (CI) was 2.70 ± 1.02 L.min.m^-2 (2.89 ± 1.04 versus 2.12 ± 0.70; p < 0.001), mean Stroke Index (SI) was 35.5 ± 14.7 mL.m^-2 (37.7 ± 15.2 versus 28.5 ± 10.8; p = 0.006), mean Ejection Phase Contractility Index (EPCI) was 33.7 ± 12.7 1000 s^-2 (35.8 ± 13.1 versus 27.2 ± 9.2; p = 0.003), mean Inotropic State Index (ISI) was 74.3 ± 28.2 100 s^-2 (78.8 ± 28.9 versus 60.6 ± 20.7; p = 0.005), and mean Left Stroke Work Index (LSWI) was 51.3 ± 23.1 g.min.m^-2 (55.4 ± 23.5 versus 38.9 ± 16.6; p = 0.002).

In this study, hypertensive patients with HF had significantly lower values of blood flow parameters, contractility, and left work indices compared with hypertensive patients without HF. These differences reflected the incorrect hemodynamic pattern (mostly hypodynamic) of these patients. Impedance cardiography (ICG) seems to be an adequate method to reflect these differences.