When in a cardiac emergency, your body turns your own worst fears against you. The more acutely you feel fear, the worse your heart problem gets. It's like the plot of IT, but without the bad special effects.
One of first books to really scare me was a children's story called Ronia, The Robber's Daughter. It was set in a magical wood, and that wood was populated by various magical creatures. One group of those creatures was called The Gray Dwarves. They would be harmless, and run away from anyone who even shouted at them, as long as that person was not afraid. If they were afraid, the creatures would get vicious, and claw, bite, and pick-axe the person to death. That trope has been picked up in a lot of horror stories. IT involved a creature that would take the form of anyone's worst fears. A Dollhouse episode featured a creature that would come after people in a computer program if they felt too much fear. But of course, that doesn't work in the real world.
Oh, but it does.
Over two years, hospital employees conducted a study that measured the fear of death of a group of people coming into the hospital with a temporarily blocked coronary artery. They also measured the level of each patient's tumour necrosis factor alpha (TNF) molecule. This molecule increases system-wide inflamation, which has been shown to damage the heart. They found that the people who reported high levels of fear had four-fold increase in inflammatory response independent of the actual severity of their condition. This worsened the episode, and not just for the moment. Three weeks later, people with high levels of fear showed low cortisol levels and low heart rate variability. Cortisol is a stress hormone. Low levels of it show that bodily inflammation is still high, making things harder on the heart. Heart rate variability serves as a measure of heart function. When the heart can't adjust well to different circumstances, heart rate variability is low. Both of these factors are bad signs.
The orchestrators of the study at St. George's Hospital in London aren't sure whether the treating the inflammation itself would have effect, or whether they would need to treat the patient's emotional response as well. For the time being they encourage doctors to reassure their patients, and encourage them to talk about their emotional state. They also want people to know that major strides in medicine make coronary artery blockage a treatable phenomenon. Although it should be treated as an emergency, it is not a harbinger of doom.
The lesson I'm taking from this is the same thing I took from the book: Fearing something makes it happen. Be afraid.
Read the full scientific article via European Heart Journal