The effects of cardiac rehabilitation on haemodynamic parameters measured by impedance cardiography in patients with heart failure.

BACKGROUND Cardiac rehabilitation (CR) is an important element of heart failure (HF) treatment although the mechanisms of its beneficial effects remain debatable. AIM To evaluate the haemodynamic effects of CR measured by impedance cardiography in patients with HF. METHODS Study group included 50 HF patients (aged 56.2 ± 8.8 years, NYHA class II and III, left ventricular ejection fraction ≤ 40%) who underwent 8-week CR. Clinical and haemodynamic assessment was performed before and after CR. RESULTS As a result of CR, exercise tolerance improved significantly as measured by peak VO(2) (18.7 ± 4.4 vs 20.8 ± 4.7 mL/kg/min; p = 0.025), six-minute walking test distance (6-MWT; 417.8 ± 103.6 vs 467.7 ± 98.4 m, p = 0.016) and NYHA class (change to the lower NYHA class in 30% of subjects). A significant reduction of the left atrial diameter was observed in echocardiography (4.55 ± 0.63 vs 4.43 ± 0.59 cm, p = 0.017). Impedance cardiography revealed a significant change in diastolic to systolic wave ratio (O/C ratio; 54.8 ± 24.0 vs 47.9 ± 20.8%, p = 0.021). A significant change in the haemodynamic profile of the left ventricular blood ejection was also observed. Before CR, transthoracic fluid content (TFC) correlated with stroke index (SI; R = 0.37, p < 0.01), compared to no correlation after CR (R = 0.00, NS). Reduction in TFC correlated with prolongation of the 6-MWT (R = -0.32, p = 0.06), and increase in systolic time ratio (STR) correlated with increase in peak VO(2)(R = 0.40, p = 0.006). Subjects who benefited from CR tended to have lower heart rate (61.4 ± 9.0 vs 67.7 ± 10.7 1/min, p = 0.07), longer pre-ejection period (PEP; 12.2 ± 11.6 ms vs -2.6 ± 23.1 ms, p = 0.018) and non-significantly higher STR (0.423 ± 0.123 vs 0.377 ± 0.102, p = 0.37). CONCLUSIONS Impedance cardiography revealed beneficial effects of CR, manifested by reduced fluid retention and a reduced effect of preload on left ventricular relaxation and ejection.