Long-term effects of device-guided slow breathing in stable heart failure patients with reduced ejection fraction

Abstract

Background: Slow breathing (SLOWB) alleviates symptoms of chronic heart failure (HF) but its long-term effects are unknown. We examined the acute and long-term impact of device-guided breathing on hemodynamics and prognostic parameters in HF patients with reduced ejection fraction (HFrEF).

Methods and results: Twenty-one patients with HFrEF (23.9 ± 5.8%, SD ± mean) on optimal medical therapy underwent blood pressure (BP), heart rate (HR), HR variability, 6-min walk test (6MWT), cardiopulmonary exercise testing (CPET), and echocardiography measurements before and 3 months after SLOWB home training (30 min daily). After 3 months, all patients were assigned to continue SLOWB (Group 1) or no-SLOWB (Group 2). All tests were repeated after 6 months. Acute SLOWB (18 ± 5 vs 8 ± 2 breaths/min, P < 0.001) had no influence on BP and HR but improved saturation (97 ± 2 vs 98 ± 2%, P = 0.01). Long-term SLOWB reduced office systolic BP (P < 0.001) but not central or ambulatory systolic BP. SLOWB reduced SDNN/RMSSD ratio (P < 0.05) after 3 months. One-way repeated measures of ANOVA revealed a significant increase in 6MWT and peak RER (respiratory exchange ratio) from baseline to 6-month follow-up in group 1 (P < 0.05) but not group 2 (P = 0.85 for 6MWT, P = 0.69 for RER). No significant changes in echocardiography were noted at follow-up. No HF worsening, rehospitalisation or death occurred in group 1 out to 6-month follow-up. Two hospitalizations for HF decompensation and two deaths ensued in group 2 between 3- and 6-month follow-up.

Conclusions: SLOWB training improves cardiorespiratory capacity and appears to slow the progression of HFrEF. Further long-term outcome studies are required to confirm the benefits of paced breathing in HFrEF.

Keywords: 6-Min walk test; Functional capacity; Heart failure with reduced ejection fraction; Heart rate variability; Hemodynamics; Slow breathing.

Fig. 1

Patient flow diagram. Study patient recruitment flow chart based on CONSORT guidelines

Fig. 2

Proportion of patients with HFrEF in four performance levels based on the distance walked (a) and changes in individual patient data in four performance levels (b) at baseline, 3- and 6-month (M) follow-up (FU). Colours indicate four different performance levels; level 1 (the lowest performance level), level 4 (the highest performance level). Numbers from 1 to 11 indicate patients in group 1 assigned to 6-month SLOWB home training, numbers from 12 to 21 indicate patients in group 2 who underwent 3-month SLOWB home training and then a 3-month observation period (b). In group 2, two patients died (boxes marked without colour) between 3- and 6-month (M) follow-up (FU)

Fig. 3

Effect of slow breathing on 6-min walk test in group 1 (a), group 2 (b) and respiratory exchange ratio (RER) in group 1 (c), group 2 (d) from baseline to 6 months (M) follow-up (FU). CPET was available in all patients at baseline, in 18 patients at 3 months (one erythema, one ICD intervention during 6MWT, one refusal) and in 14 patients at 6 months follow-up (two ICD interventions following 6MWT, one haemoptysis, one pulmonary infection, one refusal refused, two deaths)