Can anaerobic threshold be used as an end-point for therapeutic trials in heart failure? Lessons from a multicentre randomized placebo-controlled trial. The VO2 French Study Group.
Anaerobic threshold (AT), proposed as a non-invasive index of exercise tolerance, independent of patient motivation, is considered more reliable than exercise duration in assessing the effect of drug therapy in chronic heart failure (CHF). However, inter-observer variation in patients may be more difficult than in normal subjects. In a multicentre study, 85 patients from 10 centres performed a total of 331 bicycle maximal tests (ramp protocols, 10 watts.min-1) with respiratory gas analysis by different systems. A central committee reviewed all the tests. Percentages of AT determination ranged from 34% to 71% depending on the method used. Apart from the respiratory exchange ratio (RER) method, which yielded the lowest rate of determination: 34%, and the crossing point (when RER = 1), which yielded the highest rate, 71%, other methods of determination, such as carbon dioxide (42%), minute ventilation (52%) or ventilatory equivalents plotted vs time (57%), did not differ in the rate of AT determination. Thus, even among trained physicians, AT determination was not reliable. The crossing point may nevertheless be a valuable index from a pragmatic standpoint, although it occurs after the actual AT. Peak oxygen uptake should remain the main end-point in assessment of exercise capacity.
Cohen-Solal
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A
Service de Cardiologie, Hôpital Beaujon, Clichy, France.
Aupetit
J F
JF
Gueret
P
P
Kolsky
H
H
Zannad
F
F
D015308:Anaerobic Threshold / Q000187:drug effects* / Q000502:physiology; D000806:Angiotensin-Converting Enzyme Inhibitors / Q000009:adverse effects / Q000627:therapeutic use*; D004311:Double-Blind Method; D005080:Exercise Test / Q000187:drug effects*; D006333:Heart Failure / Q000188:drug therapy* / Q000503:physiopathology; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D010100:Oxygen / Q000097:blood; D015203:Reproducibility of Results
D000806:Angiotensin-Converting Enzyme Inhibitors; D007773:Lactates; D019344:Lactic Acid; D010100:Oxygen