Chest
Clinical Investigations: Exercise: ArticlesMaximal Exercise Tolerance in Chronic Congestive Heart Failure: Relationship to Resting Left Ventricular Function
Section snippets
Study Patients
Sixty-four patients with left ventricular systolic dysfunction (left ventricular ejection fraction ≤45%) and New York Heart Association (NYHA) functional class 2–4 chronic CHF, who were referred to our Cardiac Functional Testing Laboratory for functional capacity assessment were retrospectively studied. The CHF was due to either ischemic (n=20) or idiopathic cardiomyopathy (n=44). Ischemic patients had angiographically documented multivessel coronary artery disease and idiopathic cardiomyopathy
Radionuclide Data
All resting radionuclide parameters were comparable in the ischemic and idiopathic patient groups (Table 2). The LVEF, SER, and PFR were considerably reduced in both groups (normal LVEF, 69 ± 7%; SER, 3.6 ± 0.7 end-diastolic count [EDC]/s; PFR, 3.2 ± 0.7 EDC/s); TPF and FF also were lower (normal TPF, 138 ± 28 ms; FF, 40 ± 16%). Resting heart rate was comparable in both groups (82 ± 17 vs 90 ± 16 beats per minute).
Relationship Between Resting Radionuclide Data and Maximal Exercise Capacity
In the ischemic group, resting LVEF, PFR, TPF, and FF correlated poorly (p=NS)
Exercise Tolerance in Congestive Heart Failure
Since chronic CHF patients often are symptomatic only during exertion, it is important to assess their functional status in terms of their exercise tolerance.21,22 Clinical classification of CHF severity such as NYHA functional class relies solely upon the patient's subjective assessment of his or her degree of physical impairment and may therefore be inadequate in grading CHF.22,23 Objective assessment of exercise tolerance by noninvasive measurement of max (aerobic capacity) and
CONCLUSION
Despite these limitations, we can draw several conclusions from this study. Subjective assessment of NYHA functional class in CHF patients correlates well with objective measures of maximal exercise tolerance but not measures of resting left ventricular systolic or diastolic function. Resting LVEF is a poor predictor of maximal exercise tolerance in patients with CHF due to ischemic or idiopathic cardiomyopathy. Resting SER, PFR, and FF may be useful in predicting maximal exercise tolerance in
ACKNOWLEDGMENT
We thank Alfred Cecchetti for assistance with statistical analysis and Margaret Altvater for preparation of the manuscript.
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