The Rick thing in the other forum has been handled. Let's all move on now.
As far as we know, there have been no heart-attacks suffered by Frank Oz, and that's a tremendously good thing!
I think that the misconception may have been that Frank Morgan, who played the Wizard in the 1939 MGM Film "Wizard of Oz" died in his sleep from a massive heart attack. You can read about that here:
http://www.kansasoz.com/infowizard.htm
L Frank Baum who wrote "The Wonderful Wizard of Oz" had a heart attack or two:
http://www.northern.edu/hastingw/lfbaum.htm
The Pinkerton thing just seems a site of fiction and the birth of rumor. I doubt seriously anybody would have access to that information from the set, and those who would wouldn't have put it on their site, y'know?
Besides that, being that Frank Oz is such a big-time movie maker and star to millions he would have been in the news if he had had a heart-attack. CNN.com has an entertainment section that reports all that kind of stuff.