Unreliability of the %VO2 reserve versus %heart rate reserve relationship for aerobic effort relative intensity assessment in chronic heart failure patients on or off beta-blocking therapy.
BACKGROUND
Percentage of heart rate reserve (%HRR) has been shown to be equivalent to percentage of VO2 reserve (%VO2R) in normal individuals, but it is not clear whether this is also true for chronic heart failure (CHF) patients.


METHODS
This study aimed to evaluate the reliability of the %VO2R versus %HRR relationship for aerobic effort relative intensity assessment in CHF patients.


METHODS
We studied 388 patients with CHF, of whom 213 were on carvedilol (CHF on betab) and 175 were off the drug (CHF off betab), and 40 normal individuals (N). %VO2R and %HRR values were evaluated at matched steps during cardiopulmonary exercise testing. The %VO2R versus %HRR regression was determined for each group (CHF, CHF on betab, CHF off betab, N) as a whole and as the mean of individual regressions.


RESULTS
%VO2R strongly correlated with %HRR in both N and CHF, at both group and mean individual regressions, with slope and y-intercept values significantly lower and higher, respectively, in CHF than N. The 95% prediction interval of %VO2R for a given %HRR value was 24% points in N but rose to 41 in CHF, and the mean regression line coincided with identity line in N but not in CHF. These results were independent of beta-blockade.


CONCLUSIONS
In CHF patients the %VO2R versus %HRR relationship is unreliable for assessment of aerobic effort relative intensity, because of a large prediction interval of %VO2R and lack of coincidence with the identity line, independently of beta-blocking therapy. This implies that the %VO2R versus %HRR relationship should be determined directly in each patient.
Mezzani
Alessandro
A
Cardiology Division, S. Maugeri Foundation, Veruno Scientific Institute, 28010 Veruno (NO), Italy. amezzani@fsm.it
Corrà
Ugo
U
Giordano
Andrea
A
Cafagna
Michele
M
Adriano
Edvige Palazzo
EP
Giannuzzi
Pantaleo
P
D000319:Adrenergic beta-Antagonists / Q000627:therapeutic use*; D000368:Aged; D002227:Carbazoles / Q000627:therapeutic use; D002303:Cardiac Output, Low / Q000188:drug therapy* / Q000503:physiopathology*; D002311:Cardiomyopathy, Dilated / Q000188:drug therapy* / Q000503:physiopathology*; D000077261:Carvedilol; D002908:Chronic Disease; D016552:Ergometry; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D008875:Middle Aged; D005082:Physical Exertion / Q000502:physiology*; D011412:Propanolamines / Q000627:therapeutic use; D011659:Pulmonary Gas Exchange; D015203:Reproducibility of Results; D018487:Ventricular Dysfunction, Left
D000319:Adrenergic beta-Antagonists; D002227:Carbazoles; D011412:Propanolamines; D000077261:Carvedilol