Katie Couric's Notebook: Broken Hearts

But now doctors have found that heartache isn't just unpleasant… it can actually be dangerous.

The Wall Street Journal reported this weekon the curious case of Dorothy Lee, a 63-year-old woman who had what appeared to be a heart attack after learning that her husband had died.

Turns out, it was caused by a surge of adrenaline that overwhelmed her heart. "Broken-heart syndrome," also known as stress-induced cardiomyopathy, accounts for only one to two percent of heart attacks, mostly in older women. It is rarely fatal, but it can be hard to treat…and even harder to prevent.

According to a recent study led by the Minneapolis Heart Institute, possible triggers include the death of loved ones, work-related stress, sudden shock and, yes, break-ups.

So this Valentine's Day, be careful! Some hearts are more tender than others.

That's a page from my notebook.

I'm Katie Couric, CBS News.