Adverse Impact of Diastolic Heart Failure on Exercise Tolerance

Abstract

Background: While it is well known that systolic heart failure (SHF) reduces exercise tolerance and performance on the 6-minute walk test, the impact of diastolic heart failure (DHF) is less defined. Methods: We reviewed baseline clinical characteristics and performance on the 6-minute walk test for 1,063 patients with congestive heart failure, randomized into a community based study of disease management. 314 (30.0%) had DHF and 749 patients (70.0%) had SHF. All patients were asked to take an indoor 6-minute walk test at their first visit. Results: DHF patients were older: mean age was 73±10 years in DHF and 70±10 in SHF (p<0.0001). Females with HF were more likely than males to have DHF (48.0% of females compared with 21% of males, p=0.0001). DHF patients had more advanced HF with the distribution of NYHA Class I 11 vs. 22%, Class II 61 vs. 55%, and Class III/IV 27 vs. 22% in DHF and SHF respectively (p<0.0002). Systolic blood pressure (BP) was higher in DHF, both before and after the 6 minute walk test: 146±19 vs. 136±20 mmHg (p<0.0001) and 150±22 vs. 141±21 mmHg (p<0.0001) respectively. Diastolic BP was normal in both groups. DHF patients received fewer antihypertensive medications: 2.013±0.885 vs. 2.2885±0.82 (p<0.0001). DHF patients were less likely to receive ace inhibitors, 49.3% vs. 70.2% (p<0.002) and beta blockers, 32.4% vs. 59.7% (p<0.001). Four hundred patients chose not to perform the 6-minute walk, 151 with DHF (48.0% of DHF patients) and 249 with SHF (33.2% of SHF patients). More patients with DHF gave cardiac reasons for not taking the test (57.0% vs. 40%; p=0.0014). Patients with DHF walked significantly less than those with SHF, 693.59±341.5 ft vs. 862.36±331.82 ft (p<0.0001). Multivariate analysis showed this difference was independent of age, gender and NYHA class. Conclusion: DHF occurs most commonly in women and the elderly. More DHF patients avoid exercise for cardiac reasons, and have significantly lower exercise tolerance than those with SHF, independent of age, gender and NYHA class. DHF patients also had higher systolic BP and were under treated, suggesting a role for more aggressive BP control in improving quality of life in this population of patients.