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. 2020 Mar 30;9(4):952.
doi: 10.3390/jcm9040952.

Changes in Respiratory Muscle Strength Following Cardiac Rehabilitation for Prognosis in Patients with Heart Failure

Nobuaki Hamazaki  1 , Kentaro Kamiya  2 , Shohei Yamamoto  3   4 , Kohei Nozaki  1 , Takafumi Ichikawa  1 , Ryota Matsuzawa  5 , Shinya Tanaka  6 , Takeshi Nakamura  3 , Masashi Yamashita  3 , Emi Maekawa  7 , Kentaro Meguro  7 , Chiharu Noda  7 , Minako Yamaoka-Tojo  2 , Atsuhiko Matsunaga  2 , Junya Ako  7
Affiliations

Changes in Respiratory Muscle Strength Following Cardiac Rehabilitation for Prognosis in Patients with Heart Failure

Nobuaki Hamazaki et al. J Clin Med. .

Abstract

Respiratory muscle weakness, frequently observed in patients with heart failure (HF), is reported as a predictor for poor prognosis. Although increased respiratory muscle strength ameliorates exercise tolerance and quality of life in HF patients, the relationship between changes in respiratory muscle strength and patient prognosis remains unclear. A total of 456 patients with HF who continued a 5-month cardiac rehabilitation (CR) were studied. We measured maximal inspiratory pressure (PImax) at hospital discharge as the baseline and five months thereafter to assess the respiratory muscle strength. Changes in PImax during the 5-month observation period (⊿PImax) were examined. We investigated the composite multiple incidence of all-cause death or unplanned readmission after 5-month CR. The relationship between ⊿PImax and the incidence of clinical events was analyzed. Over a median follow-up of 1.8 years, 221 deaths or readmissions occurred, and their rate of incidence was 4.3/100 person-years. The higher ⊿PImax was significantly associated with lower incidence of clinical event. In multivariate Poisson regression model after adjustment for clinical confounding factors, ⊿PImax remained a significant and independent predictor for all-cause death/readmission (adjusted incident rate ratio for ⊿PImax increase of 10 cmH2O: 0.77, 95% confidence interval: 0.70-0.86). In conclusion, the changes in respiratory muscle strength independently predict the incidence of clinical events in patients with HF.

Keywords: cardiac rehabilitation; change in respiratory muscle strength; clinical event; heart failure; prognosis.

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Conflict of interest statement

The authors declare that there are no conflicts of interest.

Figures

Figure 1
Figure 1
Kaplan–Meier survival curves of the association between change in respiratory muscle strength and clinical events. (A) All-cause events and (B) cardiovascular events; Red line, patients with ⊿PImax < 0 cmH2O; blue line, patients with ⊿PImax ≥ 0 cmH2O. PImax, maximal inspiratory pressure.
Figure 2
Figure 2
Cubic spline curves of crude relationships between change in respiratory muscle strength and incidence rate of end-points. (A) All-cause events and (B) cardiovascular events; Dash lines, 95% confidence interval. IRR, incident rate ratio; PImax, maximal inspiratory pressure.
Figure 3
Figure 3
Forest plots of hazard ratios for the association of change in respiratory muscle strength with all-cause clinical events according to major subgroups. Hazard ratios were adjusted for age, sex, BMI, AHEAD score, NYHA class, and BNP at the end of the 5-month cardiac rehabilitation. BMI, body mass index; BNP, brain natriuretic peptide; IRR, incident rate ratio; NYHA, New York Heart Association functional classification; PImax, maximal inspiratory pressure; 6MWD, 6-min walk distance.
Figure 4
Figure 4
Unadjusted rates of all-cause clinical events and cardiovascular events according to categories of change in PImax per 10 cmH2O. White bars, all-cause events; black bars, cardiovascular events. PImax, maximal inspiratory pressure.
Figure 5
Figure 5
C-index of adjusted models of changes in PImax, 6MWD, and creatinine for all-cause clinical events. Data, C-index (95% CI). Models were adjusted for variables used in multivariate Poisson regression analyses. PImax, maximal inspiratory pressure; 6MWD, 6-min walk distance.
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