Don I agree with you that police being armed with tasers is a good idea, and several police officers that I know feel the same way. They would rather use a taser in leiu of a gun in any circumstances that warrant it.
As for heart attacks, a majoriy of those occur because of several (usually unknown) factors:

1) heart condition in the person being tased
2) drug use in the suspect
3) a combination of the first two
4) the improper training of police when using tasers (can be solved)

Tasers are a better choice than stun guns because you have to be in close proximity with a subject with the use ofa stun gun while the taser can be used from a relatively safer distance using darts that will penetrate several layers of clothing, yet if they miss, it can still be used as a stun gun. Stun guns are virtually ineffective through layers of clothing.
Now back to the drug user, people on PCP tend to be superhuman, and unfortunately mace doesn't even phase them and usually tasers don't either. But at least they have a better chance of subduing the person and then getting them into custody without causing their death instead of shooting to kill. Just ask the mother of a 16 year old who just got in with the wrong crowd which she would rather have, a phone call from the jailhouse, or one from the M.E.s office. You have no chance of helping the one that died. Just MHO. I could be wrong. Susu