No. You are more likely to "die if you eat them" if you didn't use the right kind or the right amount of vinegar or if you didn't process them as required than because of the lack of slits. ;)

Did you use an approved pickling recipe? One with how-to instructions? If not, then check out the Harvest forum here. It is the canning and preserving forum.

The slits are so the brine can get inside the pepper easier. Without them it will get there, it will just take longer. So you'll have to wait longer before eating.

Dave

Here is a link that might be useful: NCHFP - How to pickle peppers