Prognosis in patients with chronic heart failure: it's the way they breathe that matters

Cardiopulmonary exercise testing (CPX) is a gold-standard element of evaluation of patients with chronic heart failure (CHF), a disease of exercise. The initial rationale for cardiologists was that peak oxygen uptake (peakVO2) served as a surrogate of cardiac output. The breakthrough of CPX, however, came when Mancini's group showed that the prognostic importance of a peakVO2 threshold of 14 mL/kg/min eclipsed that of all other major clinical or functional variables (including left ventricular EF) in their cohort.1 In the ensuing years its dominance has been gnawed away, first by the increasingly disappointing rate of replication in other studies,2 and second by the emergence of alternative markers from the same test3 that focus on efficiency of pulmonary gas exchange. In the current issue of this journal Ingle et al 4 report on the predictive power of CPX data on all-cause mortality in patients with mild to moderate chronic heart failure. For individual variables they found optimal cut points located where the statistical analyses would suggest.2 They went on to develop a composite risk score for individual risk stratification. While there are already many risk scores for patients with CHF, Ingle et al include novel CPX variables like the nadir of the ventilation/carbon dioxide production ratio on exercise (VE/VCO2-nadir), the presence of exercise oscillatory ventilation (EOV) and circulatory power.5 ,6 The authors …