Are you more likely to get heart problems from using drugs that are made with substances not intended to be in drugs?

I’ve always wondered, if you take drugs that have random substances in them that the body can’t process, or isn’t designed to process (like if it’s made with rat poison or something). Is it more likely to cause your body to do weird things like heart problems, or just kill you faster? I’m not trying to do drugs, I just genuinely wonder about this.