Clinical Investigation
Poor Relationship Between Exercise Capacity and Spirometric Measurements in Patients With More Symptomatic Heart Failure

https://doi.org/10.1016/j.cardfail.2005.06.430Get rights and content

Abstract

Background

The origin of exercise limitation in patients with chronic heart failure (CHF) is multifactorial, and the relative contributions of different abnormalities may vary with severity of heart failure symptoms. The aim of the current study was to determine the extent to which spirometric indices predict peak exercise capacity in patients with differing severity of symptoms.

Methods and Results

A total of 340 patients with left ventricular systolic dysfunction underwent spirometry, and a ramped, maximal exercise treadmill test with metabolic gas exchange measurements. For comparative purposes, a group of 174 aged-matched controls with no major structural heart disease (MSHD) was also included. In a stepwise linear regression model, forced expiratory volume in 1 second (FEV1) and forced vital capacity (FVC) were independent predictors of peak oxygen uptake (pV˙O2) in controls (r2 = 18–25%; P = .001) and New York Heart Association (NYHA) I-II patients (r2 = 16–18%; P = .001). No association between spirometric indices (FEV1/FVC) and pV˙O2 (r2 = 1–2%; P > .05) was found in NYHA III-IV patients.

Conclusion

In aged-matched controls with no MSHD, spirometric variables (FEV1/FVC) explain 18% to 25% of the variance in pV˙O2, and 16% to 18% of the variance in patients with NYHA class I-II symptoms. As symptoms worsen, the influence of spirometric variables on peak exercise capacity diminishes, and there is no such relation in the NYHA class III-IV patients.

Section snippets

Methods

The Hull and East Riding ethics committee approved the study, and all patients provided informed consent for participation. Patients were recruited from a local community heart failure clinic. Inclusion criteria were: evidence of left ventricular systolic dysfunction; and symptoms of heart failure (New York Heart Association [NYHA] class I-IV). Seventy-one percent of patients had heart failure of ischemic etiology, and all had suffered from the condition for at least 6 months before the study.

Results

A total of 340 patients (82% males) with evidence of systolic heart failure (LVEF = 36 ± 9%), and 174 aged-matched controls with no MSHD (52% males) met the inclusion criteria (Table 1). pV˙O2 was higher in NYHA I-II than in NYHA III-IV patients (P = .0001) (Table 2). Similarly, other variables including pV˙CO2, pV˙E, AT, maximum heart rate (HRmax), and exercise time were higher in NYHA I-II patients. V˙E/V˙CO2 slope and resting heart rate (HRrest) were higher in NYHA III-IV patients. However,

Discussion

The results of our study, from a large group of patients with heart failure, show that as symptom severity worsens, the influence of spirometric variables on peak exercise capacity is reduced. This suggests that spirometric indices are not major determinants of reduced exercise capacity in patients with more severely symptomatic heart failure.

We found that in aged-matched controls with no MSHD, spirometric variables accounted for 18% to 25% of the variance in peak exercise capacity, whereas in

Conclusion

In aged-matched controls with no MSHD, spirometric variables (FEV1/FVC) explain 18% to 25% of the variance in pV˙O2, and 16% to 18% in patients with mild-to-moderate heart failure (NYHA I-II). There is no relationship (1% to 2%; P = .33) in more severe heart failure (NYHA III-IV), suggesting that as symptom severity worsens, the influence of spirometric variables to peak exercise capacity is reduced. Therefore, spirometric indices are not major determinants of reduced exercise capacity in

Acknowledgment

We wish to thank the reviewers for their constructive comments.

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