Diana Bass writes in a recent book:

On December 28, 2016, celebrated Hollywood actor Debbie Reynolds died at age eighty-four. The previous day, her sixty-year-old daughter, Carrie Fisher, star of the Star Wars films and noted author, had unexpectedly passed away from complications following a heart attack. A headline in the New York Times asked: "Did Debbie Reynolds Die of a Broken Heart?" And that is a real thing: stress-induced cardiomyopathy, known as “broken heart syndrome” when people who are particularly close die within a short time of one another. Indeed, that happened to my great-great-grandparents. Married for almost sixty years at a time when few people lived so long, they passed away within an hour of each other. Broken heart syndrome.

Source:

Diana Butler Bass, Grateful (Harper One, 2019), p. 28