Inspiratory muscle strength and six-minute walking distance in heart failure: Prognostic utility in a 10 years follow up cohort study

Abstract

Background Maximal inspiratory pressure (PI max ) and 6-minutes walk distance test (6MWD) may be more available and feasible alternatives for prognostic assessment than cardiopulmonary testing. We hypothesized that the PI max and 6MWD combination could improve their individual accuracy as risk predictors. We aimed to evaluate PI max ability as a mortality predictor in HF and whether the combination to 6MWD could improve risk stratification. Methods Prospective cohort from HF Clinics of three University Hospitals. PI max , 6MWD and pVO 2 were obtained at baseline. The end point was all cause mortality. Results Consecutive 256 individuals (50% woman, 57.4±10.4years) with low ejection fraction (LVEF) (31.8±8.6%) were followed up to 10years. During a median follow-up of 34.7 (IQR 37) months, 110 participants died. Mean±SD values were: pVO 2 14.9±5.1mL/kg/min, PI max 5.5±1.3kPa and 6MWD 372±118m. In multivariate Cox regression, pVO 2 , PI max , 6MWD and LVEF were independent mortality predictors. The pVO 2 showed gold standard accuracy, followed by PI max (AUC = 0.84) and 6MWD (AUC = 0.74). Kaplan-Meier mean survival time (MST±SE) for lower (≤5.0kPa) and higher (>6.0kPa) PI max tertiles, were 37.9±2.8months and 105.0±5.2months respectively, and addition of 6MWD did not restratified risk. For intermediate PI max tertile, MST was 81.5±5.5months, but adding 6MWD, MST was lower (53.3±7.6months) if distance was ≤350m and higher (103.1±5.7months) for longer distances. Conclusion PI max is an independent mortality predictor in HF, more accurate than 6MWD and LVEF. Addition of 6MWD empowers risk stratification only for intermediate PI max tertile. Although less accurate than pVO 2 , this simpler approach could be a feasible alternative as a prognostic assessment.

2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure: A Report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines

“…23 Many CPET variables have been associated with prognosis in patients with HF. 4,5,12,14,16,24 Peak exercise oxygen consumption/oxygen uptake (VO 2 ) is often used to risk stratify patients and make decisions about timing of advanced HF therapies, including heart transplantation and LVAD. In a landmark article, 7 investigators divided patients referred for heart transplantation into groups based on their peak VO 2 .…”

Role of confirmed and potential predictors of an unfavorable outcome in heart failure in everyday clinical practice

“…CPET is not often used in chronic HF patients for a few reasons, including the limited availability of equipment (relatively expensive technology, expertise required) and patient’s inability to perform a maximal effort test (comorbidities, cognitive impairment) [ 99 , 115 ]. Alternatively, severity of inspiratory muscle weakness (IMW), measured by maximal static inspiratory pressure (PImax) could be a cheap and useful parameter of inspiratory muscle strength as a marker of maximal work of breathing and can represent a reasonable alternative to pVO 2 for mortality risk stratification in HF patients [ 115 ]. In previous studies [ 115 – 118 ], PImax was a strong and independent predictor of mortality in HFrEF patients, especially in individuals unable to perform an exercise test.…”

“…Alternatively, severity of inspiratory muscle weakness (IMW), measured by maximal static inspiratory pressure (PImax) could be a cheap and useful parameter of inspiratory muscle strength as a marker of maximal work of breathing and can represent a reasonable alternative to pVO 2 for mortality risk stratification in HF patients [ 115 ]. In previous studies [ 115 – 118 ], PImax was a strong and independent predictor of mortality in HFrEF patients, especially in individuals unable to perform an exercise test.…”

Relação da Função Pulmonar e da Força Inspiratória com Capacidade Aeróbica e com Prognóstico na Insuficiência Cardíaca

“…Na IC, a redução da capacidade vital está associada à baixa PImáx e à disfunção diafragmática, 24,25 que desempenha papel significativo na limitação do exercício na ICFER 26,27 e na ICFEP 28 e demonstra relevância prognóstica independente. 29 Consistentemente com nossos achados, a disfunção e as anormalidades estruturais da musculatura esquelética generalizada, diafragmática em particular, contribuem amplamente para a intolerância ao exercício em ambas, ICFER e ICFEF. 30 Automaticidade e constante sobrecarga de trabalho, mesmo em estado de repouso, caracterizam unicamente a predisposição do diafragma à disfunção precoce na síndrome de IC, que é mais proeminente que a de outros músculos expiratórios e/ou periféricos.…”