HCM DHF part2

Great info on the first 3 questions. I will use that info in my next Dr Visit. Here are the other 3 questions (4-6) I couldn't fit in. Thanks again.
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I have HCM, history of AT/AF, DHF, 54mm LA, and 4 unsuccessful ablations. I am in normal rhythm for 6 months now b/c of success w/Fleccanaide.

In 2009, I was in sinus for a while and I felt good. I had an echo done during this time, and echo looked good, no obstruction, no big changes in the last few years. I was still sick though when in AF/AT. In Sep 09 I had my 4th ablation, and it was not successful.

Then in Feb 10, this year, my Dr wanted to risk trying Flecc (I have ICD) and it has worked. This has been the longest with  normal rhythm without an incident (6mos) since 2006. However, I do not feel as good as last time I was arrhy-free, last summer.

My atrium used to be paced 15% w/threshold of 60bpm. Now it seems my sinus node is dead b/c Im paced 100% of the time. A recent echo showed the pressures have gone up, and I have pulmonary hypertension that was not there before. Dr says atria are probably not contracting anymore, from recent scarring/ablations.
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4. TREAT/HYPERTENSION. Dr suggested silidafil as possible medication to help with hypertension. What do you think about using silidafil, risks for VFib/side effects, or us other meds to address dstlic function?

5. TREAT/PULMVEIN-STENOSIS. The hypertension med won’t help if the increased pressures are caused by stenosis of the pulmonary vein(s). Am I right? How can I treat this stenosis if it is the cause?

6.  TREAT/ADD LEAD. They suggested putting a new lead in to pace a diff part of the atrium that might better conduct contraction. Let me know your quick professional thoughts on 4-6.

[Cleveland Clinic]

4.  Sildenafil (viagra) is used to treat pulmonary hypertension, not systemic HTN, and I never heard of it being used for diastolic dysfunction.  If diastolic dysfunction is the problem in the setting of HCM, it may make matters worse.  Since you have an ICD, I think it might be reasonable to try a medication called norpace (dysopyrimide) which can help with the atach and also with the diastolic dysfunction assocaited with HCM.  Otherwise, simple beta blockers are usually very good.  
5.  The only way to treat PV stenoses is to have a dilation procedure.  Based on what you said before, it sounded like there wasn't severe stenoses of the veins.  If that's the case then the likelihood that it's the PV stenosis causing the problem is very low.
6.  That might help depending on what the current PR inteval is.  If it's very long then pacing from a different location may help.