With regard to the heart attack argument, back in the eighties, when the CAA Doctors would pull your medical very swiftly at the slightest abnormality on the ECG, the airlines protested that they were losing too many experienced pilots. The Authority therefore introduced the conditional medical certificate, allowing an "at risk" pilot to fly as long as his co-pilot had a full medical. As is the way of these things, the "at risk" group was carefully monitored. Over the succeeding years, the only pilots to suffer heart problems at the controls were those with clean medical certificates - the supposedly risky guys went on to collect their pensions. Red faces all round in the medical fraternity.
Today's aviation doctors, in the UK at least, are prepared to admit that they don't know as much about the heart as the old guard used to think. This has resulted in a much more proactive stance in getting medically grounded pilots back in the air, which has to be a good thing all round.
For what it's worth, my GP believes that if you pass 60 without any cardiac problems, you're most unlikely to have a heart attack in the future.
There are arguments for and against retirement at 60 but a dicky ticker isn't one of them.
confundemus