In heart failure prognosis is related to the severity of impairment of functional capacity.1 The peak oxygen consumption (VO₂) at cardiopulmonary exercise test (CPET) is considered the gold standard for the evaluation of exercise tolerance; nevertheless, its clinical application is limited. The 6-minute walk test (6MWT) has been proposed as a simple, inexpensive, reproducible alternative to the CPET. The 6MWT reproduces the activity of daily life and this is particularly relevant in elderly patients who usually develop symptoms below their theoretical maximal exercise capacity.2 The test showed a good reproducibility and is largely independent from aetiology of heart failure, NYHA class and indices of left ventricular systolic or diastolic function measured at rest.3

Peak VO₂ and distance walked at 6MWT have been demonstrated to have a non-linear relation and, in particular, a wide variation has been shown for pVO₂ values between 10 ml/min/kg and 20 ml/min/kg. A closer relation exists in more severe heart failure. The incremental workload nature of CPET may result in an earlier muscular exhaustion in patients with more severe disease, who otherwise may better perform in a stable workload test such as the 6MWT.

In this issue of Heart two papers deals with different aspects of the usefulness and prognostic value of 6MWT in patients undergoing aortic valve replacement (AVR) …