Abstract Aims To compare the clinical significance of exercise echocardiography (ExE) and cardiopulmonary exercise testing (CPX) in patients with ≥moderate primary mitral regurgitation (MR) and discrepancy between symptoms and MR severity. Methods and results Patients consulting for ≥moderate discordant primary MR prospectively underwent low (25 W) ExE, peak ExE, and CPX within 2 months in Lille and Rennes University Hospital. Patients with Class I recommendation for surgical MR correction were excluded. Changes in MR severity, systolic pulmonary artery pressure (SPAP), left ventricular ejection fraction (LVEF), and tricuspid annular plane systolic excursion were evaluated during ExE. Patients were followed for major events (ME): cardiovascular death, acute heart failure, or mitral valve surgery. Among 128 patients included, 22 presented mild-to-moderate, 61 moderate-to-severe, and 45 severe MR. Unlike MR variation, SPAP and LVEF were successfully assessed during ExE in most patients. Forty-one patients (32%) displayed reduced aerobic capacity (peak VO2 < 80% of predicted value) with cardiac limitation in 28 (68%) and muscular or respiratory limitation in the 13 others (32%). ME occurred in 61 patients (47.7%) during a mean follow-up of 27 ± 21 months. Twenty-five Watts SPAP [hazard ratio (HR) (95% confidence interval, CI) = 1.03 (1.01–1.06), P = 0.003] and reduced aerobic capacity [HR (95% CI) = 1.74 (1.03–2.95), P = 0.04] were independently predictive of ME, even after adjustment for MR severity. The cut-off of 55 mmHg for 25 W SPAP showed the best accuracy to predict ME (area under the curve = 0.60, P = 0.05). Conclusion In patients with ≥moderate primary MR and discordant symptoms, 25 W exercise pulmonary hypertension, defined as an SPAP ≥55 mmHg, and poor aerobic capacity during CPX are independently associated with adverse events.