It is never possible to know how it was when we were not there but,
it is possible that, the family naturally think that 'had something been done' then the person would be alive. It has been stated in the UK that modern TV medical 'dramas' over emphasise the possibility of recovering from heart attack. The scenes of a person receiving multiple 'shocks' leading to the triumphant "We got him back" are at crushing variance with real life. As others have pointed out, "You cannot shock a flat-line" Other conditions such as pulmonary embolism (and other embolism) are also very hard to detact under such difficult conditions as this case.
I searched the general question:
what percentage survive heart attack?
Here is the first answer listed and it is from the US
Science Daily.
Date: June 30, 2015
Source: National Academy of Sciences
[headline] Cardiac survival rates around 6 percent for those occurring outside of a hospital
Summary: Cardiac arrest strikes almost 600,000 people each year, killing the vast majority of those individuals, says a new report. Following a cardiac arrest, each minute without treatment decreases the likelihood of surviving without disability, and survival rates depend greatly on where the cardiac arrest occurs, said the committee that carried out the study and wrote the report.
Please search for more.
So, the fact that the event took place in the air already makes a good outcome much less likely.
herman the crab summed it up when discussing heart attack (please correct me if I have misunderstood):
In almost 15 years on the road operationally I can count on 1 hand the number of patients who left hospital to return to normal life..
I have worked in a specialised part of the funeral trade for 27 years (part time now full time) and I have heard stories of death across all those years ranging from Stillbirth to aged 104. Most people who experience a cardiac arrest - do not make it. There can be mild attacks that are sufficient to get the person to a hospital and then they are OK. Some survive the first attack but have a second one within 48/72 hours that then kills them - even if in hospital. (Notably, Ms Carrie Fisher who died four days after a cardiac event whilst trans-Atlantic)
I shall not diverge into commenting on the many other ways that people can be (apparently) fine one minute and very much not fine within minutes and, often dead within the hour. Usually, the post mortem will reveal whether the outcome was always likely to be death by seeing the damage that was done. However, families that have suffered unexpected death (from whatever cause) often flail around for any scrap of hope or other cause. I have known families who are raging about medical incompetance but the PM reveals a condition that had advanced to a considerable degree - without materially affecting the person's life - until it reached a critical moment.
I was once talking with a mature woman shop assistant - at the very moment that (I learnt later) a slowly growing brain tumour impinged on her and she was unable to speak or move within the blink of an eye. I helped carry her to the sick bay. She did not live many weeks longer.
Humans need to know certainties and if one is not to hand, they will seek them wherever they can. But death is often accompanied by wide un-certitued and questions that do not have answer.