A 62-year-old woman from Mumbai is admitted with acute inferior wall MI (ST elevation in II, III, aVF) confirmed by ECG and elevated troponin. She is haemodynamically stable (BP 118/76, HR 88). Coronary angiography reveals 100% occlusion of the right coronary artery with TIMI 0 flow. During PCI, the operator achieves TIMI 3 flow. However, 2 hours post-PCI, the patient develops sudden-onset dyspnoea, elevated JVP, clear lung bases, and hypotension (88/54 mmHg). What is the most appropriate next step in management?