Inspiratory Muscle Function and Exercise Capacity in Patients With Heart Failure With Preserved Ejection Fraction.

BACKGROUND: Heart failure with preserved ejection fraction (HFpEF) is a clinical syndrome characterized by impaired exercise capacity resulting from dyspnea and fatigue. The pathophysiological mechanisms underlying the exercise intolerance in HFpEF are not well established. We sought to evaluate the effects of inspiratory muscle function on exercise tolerance in symptomatic patients with HFpEF. METHODS AND RESULTS: A total of 74 stable symptomatic patients with HFpEF and New York Heart Association class II-III underwent a cardiopulmonary exercise test between June 2012 and May 2016. Inspiratory muscle weakness was defined as maximum inspiratory pressure (MIP) <70% of normal predicted values. Pearson correlation coefficient and multivariate linear regression analysis were used to assess the association between percent of predicted MIP (pp-MIP) and maximal exercise capacity [measured by peak oxygen uptake (peak VO2) and percent of predicted peak VO2 (pp-peak VO2)]. Thirty-one patients (42%) displayed inspiratory muscle weakness. Mean (standard deviation) age was 72.5 ± 9.1 years, 53% were women, and 35.1% displayed New York Heart Association class III. Mean peak VO2 and pp-peak VO2 were 10 ± 2.8 mL•min•kg and 57.3 ± 13.8%, respectively. The median (interquartile range) of pp-MIP was 72% (58%-90%). pp-MIP was not correlated with peak VO2 (r = -0.047, P = .689) nor pp-peak VO2 (r = -0.078, P = .509). Furthermore, in multivariable analysis, pp-MIP showed no association with peak VO2 (ß coefficient = 0.01, 95% confidence interval -0.01 to 0.03, P = .241) and pp-peak VO2 (ß coefficient = -0.00, 95% confidence interval -0.10 to 0.10, P = .975). CONCLUSIONS: In symptomatic elderly patients with HFpEF, we found that pp-MIP was not associated with either peak VO2 or pp-peak VO2.

Peak Exercise Oxygen Uptake Predicts Recurrent Admissions in Heart Failure With Preserved Ejection Fraction.

INTRODUCTION AND OBJECTIVES: Heart failure with preserved ejection fraction (HFpEF) is a highly prevalent syndrome with an elevated risk of morbidity and mortality. To date, there is scarce evidence on the role of peak exercise oxygen uptake (peak VO2) for predicting the morbidity burden in HFpEF. We sought to evaluate the association between peak VO2 and the risk of recurrent hospitalizations in patients with HFpEF. METHODS: A total of 74 stable symptomatic patients with HFpEF underwent a cardiopulmonary exercise test between June 2012 and May 2016. A negative binomial regression method was used to determine the association between the percentage of predicted peak VO2 (pp-peak VO2) and recurrent hospitalizations. Risk estimates are reported as incidence rate ratios. RESULTS: The mean age was 72.5 ± 9.1 years, 53% were women, and all patients were in New York Heart Association functional class II to III. Mean peak VO2 and median pp-peak VO2 were 10 ± 2.8mL/min/kg and 60% (range, 47-67), respectively. During a median follow-up of 276 days [interquartile range, 153-1231], 84 all-cause hospitalizations in 31 patients (41.9%) were registered. A total of 15 (20.3%) deaths were also recorded. On multivariate analysis, accounting for mortality as a terminal event, pp-peak VO2 was independently and linearly associated with the risk of recurrent admission. Thus, and modeled as continuous, a 10% decrease of pp-peak VO2 increased the risk of recurrent hospitalizations by 32% (IRR, 1.32; 95%CI, 1.03-1.68; P = .028). CONCLUSIONS: In symptomatic elderly patients with HFpEF, pp-peak VO2 predicts all-cause recurrent admission.

Heart rate response and functional capacity in patients with chronic heart failure with preserved ejection fraction.

AIMS: The mechanisms of exercise intolerance in heart failure with preserved ejection fraction (HFpEF) are not yet elucidated. Chronotropic incompetence has emerged as a potential mechanism. We aimed to evaluate whether heart rate (HR) response to exercise is associated to functional capacity in patients with symptomatic HFpEF. METHODS AND RESULTS: We prospectively studied 74 HFpEF patients [35.1% New York Heart Association Class III, 53% female, age (mean ± standard deviation) 72.5 ± 9.1 years, and 59.5% atrial fibrillation]. Functional performance was assessed by peak oxygen consumption (peak VO2 ). The mean (standard deviation) peak VO2 was 10 ± 2.8 mL/min/kg. The following chronotropic parameters were calculated: Delta-HR (HR at peak exercise - HR at rest), chronotropic index (CI) = (HR at peak exercise - resting HR)/[(220 - age) - resting HR], and CI according to the equation developed by Keteyian et al. (CIK) (HR at peak exercise - HR at rest)/[119 + (HR at rest/2) - (age/2) - 5 - HR at rest]. In a bivariate setting, peak VO2 was positively and significantly correlated with Delta-HR (r = 0.35, P = 0.003), CI (r = 0.27, P = 0.022), CIK (r = 0.28, P = 0.018), and borderline with HR at peak exercise (r = 0.22, P = 0.055). In a multivariable linear regression analysis that included clinical, analytical, echocardiographic, and functional capacity covariates, the chronotropic parameters were positively associated with peak VO2 . We found a linear relationship between Delta-HR and peak VO2 (ß coefficient of 0.03; 95% confidence interval: 0.004-0.05; P = 0.030); conversely, the association among CIs and peak VO2 was exponentially shaped. CONCLUSIONS: In patients with chronic HFpEF, the HR response to exercise was positively associated to patient's functional capacity.