New York Heart Association functional class predicts exercise parameters in the current era

Russell, Stuart D. MD
Saval, Matthew A. MS
Robbins, Jennifer L. MS
Ellestad, Myrvin H. MD
Gottlieb, Stephen S. MD
Handberg, Eileen M. PhD
Zhou, Yi MS
Chandler, Bleakley MD

^aDepartment of Medicine, Johns Hopkins Hospital, Baltimore, MD
^bDivision of Cardiology, Henry Ford Hospital, Detroit, MI
^cDivision of Cardiology, Duke University Medical Center, Durham, NC
^dLong Beach Memorial Heart and Vascular Institute, Long Beach Memorial Heart Institute, Long Beach, CA
^eDivision of Cardiology, University of Maryland School of Medicine, Baltimore, MD
^fDivision of Cardiology, University of Florida, Gainesville, FL
^gDuke Clinical Research Institute, Durham, NC
^hUniversity Hospital, Augusta, GA

Reprint requests: Stuart D. Russell, MD, Johns Hopkins Hospital, 600 North Wolfe St, Carnegie 568, Baltimore, MD 21287.

E-mail:[email protected]

ClinicalTrials.govIdentifier: NCT00047437.

Funding Source: National Institutes of Health; National Heart, Lung, and Blood Institute.

This research was supported by National Institutes of Health grants: 5U01HL063747, 5U01HL068973, 5U01HL066501, 5U01HL066482, 5U01HL064250, 5U01HL066494, 5U01HL064257, 5U01HL066497, 5U01HL068980, 5U01HL064265, 5U01HL066491, 5U01HL064264, R37AG18915, and P60AG10484.

American Heart Journal 158(4):p S24-S30, October 2009.

Background

The New York Heart Association (NYHA) functional class is a subjective estimate of a patient's functional ability based on symptoms that do not always correlate with the objective estimate of functional capacity, peak oxygen consumption (peak VO₂). In addition, relationships between these 2 measurements have not been examined in the current medical era when patients are using β-blockers, aldosterone antagonists, and cardiac resynchronization therapy (CRT). Using baseline data from the HF-ACTION (Heart Failure and A Controlled Trial Investigating Outcomes of Exercise TraiNing) study, we examined this relationship.

Methods

One thousand seven hundred fifty-eight patients underwent a symptom-limited metabolic stress test and stopped exercise due to dyspnea or fatigue. The relationship between NYHA functional class and peak VO₂ was examined. In addition, the effects of β-blockers, aldosterone antagonists, and CRT therapy on these relationships were compared.

Results

The NYHA II patients have a significantly higher peak VO₂ (16.1 ± 4.6 vs 13.0 ± 4.2 mL/kg per minute), a lower ventilation (Ve)/VCO₂ slope (32.8 ± 7.7 vs 36.8 ± 10.4), and a longer duration of exercise (11.0 ± 3.9 vs 8.0 ± 3.4 minutes) than NYHA III/IV patients. Within each functional class, there was no difference in any of the exercise parameters between patients on or off of β-blockers, aldosterone antagonists, or CRT therapy. Finally, with increasing age, a significant difference in peak VO₂, Ve/VCO₂ slope, and exercise time was found.

Conclusion

For patients being treated with current medical therapy, there still is a difference in true functional capacity between NYHA functional class II and III/IV patients. However, within each NYHA functional class, the presence or absence or contemporary heart failure therapies does not alter exercise parameters.