A novel model of exercise walking training in patients after coronary artery bypass grafting

Abstract

Background: Exercise training is an established, guideline-recommended treatment approach in cardiovascular disease. Designing novel methods of exercise training that would be accepted by the patients seems to be a way to increase patient attendance at cardiac rehabilitation (CR). The 6-min walking test (6-MWT) is a simple, safe and objective method to assess exercise capacity. In patients without heart failure, oxygen consumption after 6 min of walking reaches the ventilatory threshold (VT) level. Training up to the VT level is recommended in CR. Theoretical grounds exist for designing a novel model of CR based on diagnostic 6-MWT.

Aim: Pilot implementation and evaluation of the effectiveness of a new form of walking training based on 6-MWT in low-risk patients after coronary artery bypass grafting (CABG).

Methods: The study included 119 men after CABG undergoing phase II CR. Depending on whether patients granted a consent to undergo home-based electrocardiography (ECG) telemonitored CR or not, they were divided into two groups: group A (60 patients) - standard CR combined with the new model (walking 6 times for 6 min with 3-min intervals) for 5 days a week; and group B (59 controls) - standard CR. At baseline and after 3 and 12 months, the patients underwent the following tests: 6-MWT, 24-h Holter ECG monitoring (including evaluation of heart rate variability), and biochemical laboratory tests.

Results: No significant differences in 6-MWT distance were found between the groups at baseline and at 3 and 12 months. At 3 months, 6-MWT distance increased significantly in both groups (group A: 419 ± 73 vs. 515 ± 70 m, p < 0.02; group B: 422 ± 86 vs. 519 ± 73 m, p < 0.02). At 3 and 12 months, body mass was higher in group B controls (p < 0.05). At 3 months, glycaemia and high-sensitivity C-reactive protein (hsCRP) levels were significantly lower in group A patients (p < 0.05). At 12 months, triglyceride levels were higher in group B (p < 0.05). At 3 months, SDNN was higher in group A. After 12 months, LF was lower in group A. At baseline, the LF/HF ratio was significantly higher in group A (p < 0.05) but during further follow-up, favourable changes in the LF/HF ratio were noted only in group A.

Conclusions: The novel model of exercise walking training had a favourable effect on body mass, glycaemia and hsCRP level reduction, and induced favourable changes of the sympathovagal balance.