I was on Alli for 6 months recently. It helped me lose 30 pounds and keep it off.
I stopped taking it back in December because I had surgery and didn't want any problems before or during the surgery and during the recovery. I am ready to start back on Alli soon when I get the money to buy another bottle, as it is definitely a helpful tool.
As far as heart problems- my heart races whenever I have any caffeine, so just about every diet pill out there would be a no-no for me. However, Alli caused no problems with my heart racing, but I would still ask your doctor just to be on the safe side.
I remember way back when I belonged on their site's message board, someone had had a heart problem (I forget which, sorry) and asked if it was safe. They said so long as they took a daily vitamin once or twice a day, they would be ok, as it doesn't affect the heart. That was a couple of years ago when I first started Alli, but stopped due to how expensive it was, so I don't know if the poster ever used it or what their results were.
The only problem that I had with side effects, which was
MY fault and not Alli's- I didn't stop long enough before I went on vacation, ate way too much fat, and ended up with cramps in my stomach and had a lot of diarrhea, for about 3 days- we're talking non-stop, on the toilet once an hour for about 14 hours a day. How I knew it was the Alli? The orange fat that came out of me every time I went to the bathroom, and believe me, there was a lot of it. Thank you GOD that I had a porta potty in my tent trailer, as I would never have made the bathroom at the campground. It was in my third day in on our vacation that this started, and it was because I didn't wean myself off at least an entire week off of the Alli before eating fatty foods. I lost five pounds in that ten days of camping, and I'm sure the Alli was to thank for that.
When I say wean yourself off, I mean stop taking it, but
EAT LOW FAT for at least another week to avoid problems. This was also the only time I had one accident in my underwear, and again, this was MY fault for not being diligent and following directions. I stopped taking it again a couple of other times when I went on other vacations and had no problems, but again, I ate low fat for that week it was leaving my system, very important that you do this.
I love Alli, I just wish it was cheaper.
Hope this helps.