First, I am so sorry about your heart condition. That must be very difficult for you, physically and emotionally.
I don't think anyone can say how accurate the 'net is for medical info. I would be more likely to trust sites that are connected to major universities or hospitals, such as John Hopkins, etc.
New medical information is discovered every day and it can change treatments and prognoses. I think a doctor could only guess at the lifespan question and I think a doctor would have to reserve the right to change that answer as time passes and symptoms change and responses to treatments are evaluated. But I would want to know too; at least a 'best-guess' or ballpark estimate. Before you ask the question, be sure to tell your doctor you want all the facts and that you need to know.
I hope for the very best for you, Wanda. I will certainly keep you in my thoughts.