Twenty years ago today, we lost Joe Strummer. Here was his cause of death.

Twenty years ago today–December 22, 2002–former Clash frontman and all-round punk icon Joe Strummer took his dog for a walk in Quantock Hills, Somerset, England. When he returned to the house, he walked into the kitchen, moved to the sofa in the living room, sat down and died. Just…died. He was found by his wife Lucinda.

The cause of death was an undiagnosed congenital defect in his heart called an “intra-mural coronary artery.” This is when one of the main vessels supplying blood to the heart slowly ends up growing abnormally inside the heart muscle itself. Eventually, the artery gets squeezed shut and a heart attack results, followed by death.

This is an incredibly rare condition with only 100 fatal deaths worldwide in the last 50 years. Because no one ever looks for an intra-mural coronary artery, no one ever knows that it’s there until it’s too late.

And there’s no reason Joe should have had any suspicions about his heart. Yeah, he smoked and drank, but was anti-drugs and had been a vegetarian since 1971. He was also a regular runner, competing in a couple of marathons. And he’s killed by a heart attack? No one saw that coming.

There are many celebrations going on this week. Here are a few.

• Busking in front of the Joe Strummer mural in NYC.
• Revisiting his final concert.
• Looking back at Joe’s love of Spain.
• Joe’s ten greatest songs.

There’s an Ongoing History of New Music show on the 20th anniversary of Joe’s passing, too. The podcast is available wherever you download podcasts.

Here’s the only time I got to meet Joe. This would be about 1999.