A 44-year-old obese, hypertensive woman presents with dyspnea on exertion. On exam, she has a diastolic rumble and a loud S1. Echo shows LA dilatation with typical MS. The mean gradient at rest is 6 mmHg (heart rate 85 bpm) and the MVA is calculated as 1.7 cm2 by PHT method. Systolic PA pressure is ~35 mmHg at rest. The valve is pliable, not heaviliy calcified, with a Wilkins score of 7. With exercise testing, the gradient increases to 12 mmHg and systolic PA pressure increases to 45–50 mmHg. What is the next step?