Following a long recovery process, a public shaming, and a victory in arbitration last week, sushi-poisoned Broadway star Jeremy Piven is back, sort of! He was on Letterman last night to further explain his departure from last year's Speed-the-Plow to a skeptical Dave. He acknowledged that mercury poisoning might seem like "a rich man's disease ... like something you might get from the leather seats in your Lamborghini," to much laughter and applause. But things quickly turned serious: "A cardiologist of almost 30 years said, 'Here's the deal,' " Piven recalled. " 'You can't go back and do eight shows a week, you simply can't ... unless you want to have a heart attack.' " Luckily, he did the right thing and quit immediately, leaving producers and cast mates in the lurch. While you're waiting for the inevitable follow-up press release from the National Fisheries Institute, click to watch the video!