In an article in the Toronto Star today, it says:
Police forces across Canada, including the RCMP and OPP, are immediately changing their Taser use policy after the manufacturer issued a directive that officers should not aim the weapon at a suspect's chest.
Taser International said in a bulletin that it's no longer advisable to aim the conducted energy weapon, which sends out a jolt of electricity, at a target's chest area to avoid impact to the heart.
"[W]e have lowered the recommended point of aim from centre of mass to lower centre of mass for front shots," the company said in a new training bulletin.
Not wanting to make light of it, because I hope no cop ever feels the need to taser me, but there are a lot of guys who would prefer the risk of damage to their heart to the possibility of damage to their "you know" which happens to be down near the lower centre of mass area.