Ventilatory expired gas at constant-rate low-intensity exercise predicts adverse events and is related to neurohormonal markers in patients with heart failure.
BACKGROUND
Ventilatory efficiency (VE/VCO(2) ratio) and the partial pressure of end-tidal carbon dioxide (P(ET)CO(2)), obtained during moderate to high levels of physical exertion demonstrate prognostic value in heart failure (HF). The present investigation assesses the clinical utility of these variables during low-intensity exercise.


RESULTS
One hundred and thirty subjects diagnosed with HF underwent a 2-minute, constant-rate treadmill session at 2 miles per hour. Both the VE/VCO(2) ratio and P(ET)CO(2) were recorded during exercise (30-second average) and their change (Delta) from rest. B-type and atrial natriuretic peptide (BNP and ANP) were also determined. Only P(ET)CO(2) and DeltaP(ET)CO(2) emerged from the multivariate Cox regression. Receiver operating characteristic curve analysis revealed the prognostic classification schemes were significant with thresholds of < or >or=34 mm Hg (hazard ratio: 4.2, 95% CI: 2.2-8.0, P < .001) and < or >or=1 mm Hg (hazard ratio: 3.5, 95% CI: 1.9-6.6, P < .001) being optimal for P(ET)CO(2) and DeltaP(ET)CO(2), respectively. Moreover, subjects with a P(ET)CO(2)>or=34 mm Hg had a significantly lower BNP (214.1 +/- 431.9 vs. 1110.5 +/- 1854.0 pg/mL, P=.005) and ANP (108.2 +/- 103.6 vs. 246.2 +/- 200.4 pg/mL, P < .001).


CONCLUSIONS
The results of this pilot study indicate ventilatory expired gas analysis during a short bout of low-intensity exercise may provide insight into prognosis and cardiac stability.
Arena
Ross
R
Department of Physical Therapy, Virginia Commonwealth University, Health Sciences Campus, Richmond, Virginia 23298-0224, USA. raarena@vcu.edu
MacCarter
Dean
D
Olson
Thomas P
TP
Lalande
Sophie
S
Ceridon
Maile L
ML
Olson
Lyle J
LJ
Johnson
Bruce
B
D000328:Adult; D000368:Aged; D015415:Biomarkers / Q000097:blood; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test / Q000379:methods; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006333:Heart Failure / Q000097:blood* / Q000150:complications / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D018377:Neurotransmitter Agents / Q000097:blood*; D010101:Oxygen Consumption / Q000502:physiology; D010865:Pilot Projects; D011237:Predictive Value of Tests; D012123:Pulmonary Ventilation / Q000502:physiology*
D015415:Biomarkers; D018377:Neurotransmitter Agents