Chest
Volume 106, Issue 6, December 1994, Pages 1746-1752
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Clinical Investigations: Exercise: Articles
Maximal Exercise Tolerance in Chronic Congestive Heart Failure: Relationship to Resting Left Ventricular Function

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The relationship between maximal exercise tolerance and resting radionuclide indexes of left ventricular systolic and diastolic function were evaluated in 20 ischemic and 44 idiopathic cardiomyopathy patients with New York Heart Association class 2–4 chronic congestive heart failure. Left ventricular ejection fraction, peak systolic ejection rate, peak diastolic filling rate, time to peak filling from end-systolic volume, and fractional filling in early diastole were measured from the radionuclide ventriculogram. All patients underwent symptom-limited exercise testing with on-line measurement of oxygen consumption. In the ischemic group, all of the radionuclide indexes correlated poorly with maximal exercise oxygen consumption ( V˙o2max) except the peak systolic ejection rate which correlated modestly (r=0.58, p<0.05). Peak systolic ejection rate was significantly lower (p<0.01) as were the peak diastolic filling rate and fractional filling in the first third of diastole (p<0.05) in ischemic patients with marked exercise intolerance ( V˙o2max≤14 mL/kg/min) compared with those with preserved exercise tolerance ( V˙o2max >14 mL/kg/min). In the idiopathic group, none of the radionuclide indexes correlated well with V˙o2max; and all indexes were similar in patients with and without marked exercise intolerance. These data suggest that (1) resting left ventricular ejection fraction poorly predicts maximal exercise capacity in both ischemic and idiopathic cardiomyopathy and (2) resting peak systolic ejection rate, peak diastolic filling rate, and fractional filling in early diastole may predict exercise tolerance in ischemic but not idiopathic cardiomyopathy.

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 V˙o2max (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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