AIMS: To evaluate the haemodynamic effect of acute procedural success (APS) after MitraClip therapy in patients with haemodynamic decompensation. METHODS AND RESULTS: Of 107 patients, 79 achieved APS after MitraClip implantation. The increase in cardiac index (CI) was primarily detected in patients with a low baseline CI (2.0 ± 0.5 to 2.5 ± 5 L/min/m(2), P < 0.001). There was a decrease in left ventricular end-diastolic pressure (LVEDP) (20 ± 5 to 13 ± 5 mmHg, P = 0.002) and mean pulmonary capillary wedge pressure (PCWPm) (20 ± 4 to 16 ± 5 mmHg, P = 0.001) in patients with values >15 mmHg at baseline, and a decrease in mean pulmonary artery systolic (PAPm) (36 ± 4 to 29 ± 7 mmHg P = 0.003) in those with values >30 mmHg before the MitraClip procedure. Patients with decompensation compared with patients with compensation experienced significant reduction in LVEDP (-8.3 ± 11.9 mmHg vs. -0.2 ± 4.5 mmHg, P = 0.009), a reduction in PCWPm (-3.5 ± 5.6 mmHg vs. 1.9 ± 4.7 mmHg, P < 0.001), and a reduction in PAPm (-8 ± 9 mmHg vs. 3 ± 6 mmHg, P < 0.001). CONCLUSION: The favourable haemodynamic effects of MitraClip therapy on CI were primarily detected in patients with low CI before the procedure, and improvements in left-sided filling pressure and PAP were primarily seen in those with elevated values at baseline.