New York Heart Association functional class predicts exercise parameters in the current era.
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 V(O2)). In addition, relationships between these 2 measurements have not been examined in the current medical era when patients are using beta-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 V(O2) was examined. In addition, the effects of beta-blockers, aldosterone antagonists, and CRT therapy on these relationships were compared.


RESULTS
The NYHA II patients have a significantly higher peak Vo(2) (16.1 +/- 4.6 vs 13.0 +/- 4.2 mL/kg per minute), a lower ventilation (Ve)/V(CO2) 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 beta-blockers, aldosterone antagonists, or CRT therapy. Finally, with increasing age, a significant difference in peak Vo(2), Ve/V(CO2) slope, and exercise time was found.


CONCLUSIONS
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.
Department of Medicine, Johns Hopkins Hospital, Baltimore, MD 21287, USA. srusse14@jhmi.edu
Stuart D
SD
Russell
Matthew A
MA
Saval
Jennifer L
JL
Robbins
Myrvin H
MH
Ellestad
Stephen S
SS
Gottlieb
Eileen M
EM
Handberg
Yi
Y
Zhou
Bleakley
B
Chandler
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use; D002304:Cardiac Pacing, Artificial / Q000379:methods; D003625:Data Collection / Q000706:statistics & numerical data; D004562:Electrocardiography; D005080:Exercise Test / Q000145:classification / Q000706:statistics & numerical data*; D017079:Exercise Tolerance; D005260:Female; D006321:Heart / Q000503:physiopathology; D006333:Heart Failure / Q000175:diagnosis / Q000503:physiopathology* / Q000628:therapy; D006801:Humans; D008297:Male; D008875:Middle Aged; D000451:Mineralocorticoid Receptor Antagonists / Q000627:therapeutic use; D010101:Oxygen Consumption / Q000502:physiology*; D012123:Pulmonary Ventilation / Q000502:physiology; D012720:Severity of Illness Index; D016896:Treatment Outcome; D018487:Ventricular Dysfunction, Left / Q000503:physiopathology / Q000628:therapy
D000319:Adrenergic beta-Antagonists; D000451:Mineralocorticoid Receptor Antagonists