I was thinking more along the lines of "Massive Coronary" (i.e. actual NNDK damage if you really want to specific damage rules). Ageing a year itself is still an undefined thing in HERO. Why would being 91 be any worse than 90?
Something like "Physical Complication: Old Age" would be enough. Or "Susceptability: 1d6 STUN and BODY from Pushing powers".