The heart is a finicky little machine at best. It has to pump close to 2,000 gallons per day nonstop, and all four chambers have to be working - and communicating - at the right time or else things go south. A few "hiccups" in the system can be dealt with, but even the most minor problem can become life-threatening if we ignore it.
Three years ago, I went down face-first on a Wal-Mart floor not once, but twice in about two minutes. When the EMTs finally woke me up, I was confused, embarrassed, and just wanted to buy my groceries and go home so I could take a nap. They took me by force in an ambulance with tubes and electrodes everywhere, and it wasn't until about four hours later that I was informed I'd had a heart attack due to a branch bundle block (essentially an electrical problem where one chamber doesn't send signal to the next).
There was no pain, no shortness of breath, none of the "classic" symptoms. Just a slightly queasy, nauseated feeling, and suddenly *poof* I was out like a light. I had no idea I'd had a heart attack. My cholesterol and BP have always been low, so there was never any sign of danger.
Scary thing is, a BBB cannot be predicted. It cannot be treated, except with a pacemaker. So there was no 'danger' sign to look out for.
Every day, we take the internal workings of our bodies for granted. We assume that our hearts will beat, our lungs will breathe, our inner ears will keep us upright, and our brains will direct traffic. And at any given moment, something can go wrong.