Can Ectopic Heart beats trigger A-fib if you haven't had A-fib before?

Hello, I’m a 41 year old female. Around 2 and a half years ago, I started having SVT, PVC’s, PAC’s, and an increase in sinus tach – which started when I was in college. I’ve had lots of testing and have been told that I have a structurally normal heart, no heart disease, etc. My ejection fraction is 70%, my blood pressure tends to run a bit low, and my cholesterol is optimal. I exercise everyday and try to eat healthy food. I do not take any medication.
Almost 2 years ago I had an ablation which was successful in treating the SVT. I haven’t had any episodes since then.

I still have PAC’s, PVC’s and sinus tach. Testing from a year and a half ago shows that I have around 150 of each a day. Some days I don’t notice any, but when I’m stressed out, I notice more – sometimes up to 20. (This just happened over the holidays.) I’ve been told that they are benign. I still get a little nervous when I have the ectopic heartbeats. This is based on reading some contradictory things. I’ve read that they can trigger A-fib, and this frightens me.

My question are:
1. Could PAC’s and PVC’s trigger A-fib in me? (I’ve never had A-fib before, and I’ve been having them for 2  
                years and the ablation didn’t trigger A-fib.)
2. If they can trigger A-fib – what is the likelihood of this?
3. My new eletrophysiologist does not think that I need to have any more testing. He says I’m too young to
                 need another stress test or echo. Do you agree? (I’ve read that frequent sinus tach can lead to heart
                failure.)

Thank you for your help!

[CCFHeartMD10]

1. Certain types of PACs can trigger atrial fibrillation in susceptible people. However in this case we usually see repetitive firing from a "trigger" and not isolated PACs. PVCs are much less likely to trigger atrial fibrillation however it is possible. 150 of either a day is not an excessive number. As you no doubt know, everybody gets both PACs and PVCs, every day. In the absence of actually having episodes of atrial fibrillation treatment for PACs would not be recommended.
2. PACs can trigger atrial fibrillation, and PVCs are much less likely to trigger atrial fibrillation. An estimate of how likely is very difficult, but consider that only about 2% of people your age have atrial fibrillation.
3. Given that previous tests have shown a structurally normal heart and normal amounts of ectopics, further testing may not be neccessary in the absence of specific symptoms. Sinus tachycardia describes the normal increase in heart rate in response to exercise or stress. While there are some reports associating sinus tachycardia with cardiomyopathy, it is difficult to distinguish cause and effect in these cases and there are likely other factors at play in many of them. Certainly the heart rate would have to have to be very high (for instance 180bpm) almost all the time to have this effect, and this is extremely unusual.

[fwilson]

I am curious about the comment, "Everybody gets both PACs and PVCs everyday."  It was my understanding that when populations were studied with holter monitoring, only a percentage saw even a single ectopic throughout the day.