Primary mitral regurgitation (MR) is the second cause of valvular surgery in Europe. Early surgery seems to improve long term prognosis, raising the need of prognostic markers.

Evaluate the prognostic value of %VO₂max, assessed by cardiopulmonary echocardiography exercise test (CPEET), in terms of free-of-cardiovascular-event survival.

The patients underwent CPEET for primary MR between march 2012 and march 2019. Clinical follow-up of a composite cardiovascular event (cardiovascular death, heart failure progression ≥1 NYHA stage or unplanned hospitalization for heart failure, de novo atrial fibrillation, systemic embolic event, symptomatic ventricular tachycardia).

180 patients were analysed, with a median follow-up of 33 months. Free-of-events survival at 48 months was significantly associated with % VO_2max<80% predicted (38.5% vs. 62.3%, P<0.0001), with circulatory power<3500 (29.8% vs. 61.7%, P<0.0001), with half time recovery of VO₂>180s (42.3% vs. 58.1%, P=0.001) and with maximal effort sPAP>60mmHg (42.2% vs. 67.8% P=0.006) in univariate analysis. In multivariate analysis the impairment of %VO_2max<80% predicted, was an independent predictor of free-of-event survival [HR=0.96 (0.94;0.98), P<0.0001].

An impairment of functional capacity, assessed by a cardiopulmonary-echocardiography-exercise-test with a %VO_2max<80% of the predicted value, independently predicts cardiovascular events in primary MR. This parameter should be considered as an equivalent of symptoms and for this reason indicate an early surgical repair of the mitral valve. CPEET is a feasible and worthwhile exam, and should be considered in the evaluation of asymptomatic patients with severe MR.