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.