Just to clarify terminology. Heart attack is not the same as cardiac arrest.
Basically a heart attack is when the arteries to the heart become occluded causing chest pain and (as time goes by) cardiac muscle damage.
A cardiac arrest is where the heart is unable to pump blood to supply the brain causing a loss of consciousness. Cardiac arrest can be caused by arrhythmias, large blood clots in the lung and also heart attacks where either a large part of the heart is infarcted or because an arrhythmia develops secondary to infecting an important conducive pathway in the heart.

The majority of heart attacks cause chest pain and no loss of consciousness but the ones that do cause LOC have a poor survival rate.
When someone collapses like this you have no idea what the cause is but if they are not breathing then you should call for help and start CPR immediately.
Defibrillators are found on tube stations, supermarkets etc and are designed for members of the public to use - they talk you through the steps.
The pads analyse the rhythm of the heart to see if it's a 'shockable' rhythm. If it's not then no shock will be delivered which is why it's essential that CPR has been started and is maintained until help arrives.

A common misconception (in tv/movies) is that a 'flat line' can be shocked back into a normal rhythm when in fact if the defibrillator reads a 'flat line'( technical term asystole) then it will not initiate a shock.

You can see from the top view that most certainly did the truck not save him. He would have been close but clear if it had only been the train. About as close as someone might stand at a underground tube station.

According to wikipedia Kreegath is right, I just checked it after reading about the Moscow metro in a novel. Angel tube station's escalators dates: vertical rise of 27.4 m (90 ft) and a length of 60 m (197 ft) - Park Pobedy's dates: 740 steps, and 126 m long, the station is 97 metres underground. I'm not sure about this particular station but in general some of the metro stations built after the beginning of the Cold War were intended to be used as shelters in the case of an emergency which explains the depth of the station.

so... the "intelligence" services were following them for a year, but didn't manage to stop them, and in fact shot an innocent guy who happened to live in the same flat, but only after the innocent guy actually got into the tube station.

WAY TO GO!

conspiracy or stupidity... nothing else makes sense.