Clinical InvestigationPoor Relationship Between Exercise Capacity and Spirometric Measurements in Patients With More Symptomatic Heart Failure
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). was higher in NYHA I-II than in NYHA III-IV patients (P = .0001) (Table 2). Similarly, other variables including , , AT, maximum heart rate (HRmax), and exercise time were higher in NYHA I-II patients. 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 , 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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