The Metabolic Exercise combined with Cardiac and Kidney Indexes [MECKI) score is a validated prognostic score for heart failure with reduced ejection fraction which combines commonly available clinical and metabolic parameters with two cardiopulmonary exercise test derived prognostic measurements. It has been validated to predict prognosis and to aid clinical decision making and it has been shown to be superior in predicting mortality compared with other commonly used prognostic scores for heart failure. In the future it would be valuable to establish whether the score holds true also in other settings, and in particular in under-represented groups – the elderly, women, and people of different ethnic backgrounds – and in other heart failure syndromes. In future it may be extended to assess its value in the presence of a range of co-morbidities such as chronic obstructive pulmonary disease, pulmonary hypertension and frailty and cachexia as well as in other conditions such as hypertrophic cardiomyopathy, amyloid, asymptomatic left ventricular dysfunction and hypertension. It may also be a candidate end-point for adaptive trials designed to prove an improvement in the MECKI score as an approvable interim end-point whilst larger mortality and morbidity trials are still underway.