Thank you for your query at DoctorSpring.com
The extent to which you shall experience improvement after revascularization depends on the viable but ischemic myocardium. If a large area of myocardium is already damaged then the chances of improvement are very less. The possibility of improvement can be ascertained preoperatively by doing a pet scan for viable ischemic and non-viable myocardium. That if done preoperatively will give a fair idea of how much improvement to expect. The time frame of improvement is again unpredictable from weeks to months. Also, the breathlessness could be due to many other factors like lung disease secondary to smoking low hemoglobin poor exercise capacity etc.
Dr Vivek Mahajan