Unfortunately the combination of age, destination and medical condition do not make your dad an attractive risk to insurers. Again check with the companies listed here on MSM (if you haven't already). Whilst the initial outlay may be high it could still be money well spent.

Good luck

My Dad has had 2 heart attacks over 10 years ago and a heart bypass in Aug 04 ... My mum & dad wish to travel to the USA but all quotes are very high (as he is 66). Any suggestions on where to get cheaper quotes! lol