A crucial aspect of perioperative medicine is risk prediction. The gold standard, objective test of cardiopulmonary fitness is cardiopulmonary exercise testing at maximum exertion. Its availability, expense, and contraindications for people with specific comorbidities all limit its use. Tests of submaximal exercise, such as the 6-minute walk test, provide an affordable, well-tolerated alternative, but patient effort can affect the results. Its availability, expense, and contraindications for people with specific comorbidities all limit its use. Heart rate recovery-area under the curve, a new heart rate recovery measurement metric that we developed, outperforms existing markers across a range of exercise intensities in healthy volunteers in terms of repeatability and effort dependence.
