The initial slope of the VCO2/VO2-curve (s1) in cardiopulmonary exercise testing is a strong and independent predictor of outcome in patients with previous myocardial infarction

Background  Detecting heart failure (HF) patients at risk is a relevant clinical problem. Our goal was to define associations of clinical HF-markers and exercise parameters with respect to their prognostic power in HF-patients. Methods  We performed cardiopulmonary exercise testing (CPET) in 103 ischemic HF-patients. CPET-parameters included peak VO₂, VO₂ at AT, peak oxygen pulse, minimal CO₂ and O₂ equivalents, VE/VCO₂ and s1, a motivation-independent and submaximal parameter representing the initial slope of the VCO₂/VO₂-curve that has not been described in HF-patients so far. Results  Median follow-up was 668 days. The combined endpoint of cardiovascular death and rehospitalization due to HF occurred in 14 patients. Patients with/without events differed significantly regarding their age, NYHA-class, LVEF and NT-proBNP serum-levels. Patients with events had significantly lower peak VO₂- and higher s1-values. NT-proBNP serum-levels, NYHA-class and LVEF were significantly correlated with peak VO₂. Only age, peak VO₂ and s1 were independent predictors of adverse events. Using multivariate analysis, s1 was a strong and independent parameter with good sensitivity and specificity. Conclusion  s1 is an independent and powerful predictor in HF-patients. Since s1 is independent of maximal exercise capacity, s1 might be more accurate for the evaluation of HF-patients not willing or unable to perform maximal exercise.