The role of exercise ventilation in clinical evaluation and risk stratification in patients with chronic heart failure.
BACKGROUND
Patients with chronic heart failure (CHF) are characterised by an increased ventilatory response to exercise. The role of exercise ventilation in the risk stratification and evaluation of patients with CHF has not yet been established.


OBJECTIVE
To examine the relationship between exercise ventilation indices and clinical parameters of CHF and to assess the prognostic value of the ventilatory response to exercise.


METHODS
The study group consisted of 87 patients with CHF (72 males, mean age 58 years) with a mean left ventricular ejection fraction of 32%. Ten patients were in NYHA class I, 38 - in NYHA class II, 34 - in NYHA class III, and 5 - in NYHA class IV. The control group consisted of 20 patients without CHF (13 males, mean age 58 years, mean LVEF - 61%). All studied subjects underwent maximal exercise test with gas-exchange measurement. The following parameters were analysed: peak exercise oxygen consumption [peak VO(2) (ml/kg/min)], VE-VCO(2) index [a coefficient of linear regression analysis depicting an association between ventilation (VE) and carbon dioxide production (VCO(2)) during exercise] and VE/VCO(2) ratio at peak exercise to VE/VCO(2) ratio while at rest (VE/VCO(2 peak/rest)).


RESULTS
Ventilatory response indices were significantly higher in patients with CHF compared with controls: VE-VCO(2) - 37.9+/-11.1 vs 27.1+/-4.1; VE-VCO(2 peak/rest) - 0.89+/-0.14 vs 0.75+/-0.10 (p<0.001). In CHF patients a significant positive correlation between ventilatory response parameters and NYHA class (VE-VCO(2) - r=0.52; VE/VCO(2 peak/rest) - r=0.47) and a negative correlation with peak VO(2) (VE-VCO(2) - r=-0.52; VE/VCO(2 peak/rest) - r=-0.49) were noted (p<0.0001 for all correlations). No correlation was found between ventilatory parameters and echocardiographic variables or CHF aetiology. During the follow-up period lasting at least 12 months, 17 (22%) patients died. In the univariate Cox model, NYHA class III-IV, decreased peak VO(2) and increased VE-VCO(2) and VE/VCO(2 peak/rest) values were significantly associated with the risk of death. The multivariate analysis revealed that VE/VCO(2 peak/rest) > or =1.0 was the adverse prognostic factor, independent of peak VO(2) (p=0.02) and NYHA class (p=0.01). The Kaplan-Meier analysis showed that prognosis during the 18-month follow-up period in patients with enhanced exercise ventilation was worse than in the remaining patients (59% survival in patients with VE/VCO(2 peak/rest) > or =1.0 59% vs 91% survival in patients with VE/VCO(2 peak/rest) <1.0, p=0.001).


CONCLUSIONS
In patients with stable CHF simple exercise ventilation parameters may provide important clinical and prognostic information.
Jankowska
Ewa A
EA
Department of Cardiology, 4th Military Clinical Hospital, Wrocław, Poland.
Pietruk-Kowalczyk
Jolanta
J
Zymliński
Robert
R
Witkowski
Tomasz
T
Ponikowska
Beata
B
Sebzda
Tadeusz
T
Rzeczuch
Krzysztof
K
Borodulin-Nadzieja
Ludmiła
L
Hańczycowa
Halina
H
Banasiak
Waldemar
W
Ponikowski
Piotr
P
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002245:Carbon Dioxide / Q000378:metabolism; D018450:Disease Progression; D004452:Echocardiography; D005080:Exercise Test; D017079:Exercise Tolerance; D005260:Female; D006333:Heart Failure / Q000175:diagnosis* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D006801:Humans; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption; D011237:Predictive Value of Tests; D011379:Prognosis; D016016:Proportional Hazards Models; D011659:Pulmonary Gas Exchange; D012123:Pulmonary Ventilation; D018570:Risk Assessment; D012720:Severity of Illness Index; D013147:Spirometry; D015996:Survival Rate
D002245:Carbon Dioxide