Cardiologists believe they’ve found a surprising new trigger for the condition commonly known as “broken heart syndrome”: joy. The doctors have just published their findings in the European Heart Journal

The technical term is takotsubo syndrome (TTS) or takotsubo myopathy. Sudden weakening of heart muscles can distort the heart’s left ventricle, forcing it to expand at the bottom and resulting in a shape similar to a takotsubo, or Japanese octopus trap. Because TTS is frequently triggered by intense emotions like anger, fear, and grief, it’s also known as “broken heart syndrome.” The condition most frequently affects older women, but has been known to affect a wide range of adults.

But the authors of the new paper weren’t so sure “broken heart” was the right term. They wondered if happy events could trigger TTS, too. 

To find out, they tapped into the International Takotsubo Registry, which yielded case reports on 1750 patients from nine different countries. Of those 1750 cases, 485 had clear emotional triggers. Most of these were clearly negative: 30 patients were diagnosed after the death of a spouse, and 16 after attending funerals. Car accidents triggered TTS in 11 patients, while family arguments accounted for another 17 diagnoses. One person developed TTS after a nightmare, while another came down with the condition after losing her purse. The extent of the emotional trauma varied, but the majority fit the “broken heart” stereotype.

But there were a few patients whose TTS arose after happy or exciting events. The doctors classified 20 people, or 4 percent of the emotional-onset TTS cases, as experiencing what they termed “happy heart syndrome.” Triggers included the birth of great-grandchildren, winning at the casino, attending a wedding, and getting good news from a doctor. Three of the 20 cases were related to birthday parties. The authors found this especially interesting, because, as they noted, previous studies have shown that people predisposed to heart problems are 27 percent more likely to have a cardiac event on their birthdays. 

The “happy heart syndrome” patients were very similar to those in the “broken heart” category, with one exception: Their hearts were more likely to have ballooned up mid-ventricle (as opposed to near the bottom). 

A 4 percent prevalence is pretty small, but the researchers say it’s worth further study. "We have shown that the triggers for TTS can be more varied than previously thought,” co-author Jelena Ghadri said in a press release. “A TTS patient is no longer the classic ‘broken hearted’ patient, and the disease can be preceded by positive emotions too. Clinicians should be aware of this and also consider that patients who arrive in the emergency department with signs of heart attacks, such as chest pain and breathlessness, but after a happy event or emotion, could be suffering from TTS just as much as a similar patient presenting after a negative emotional event."

While it's a recent discovery, the concept isn't new. "We believe that TTS is a classic example of an intertwined feedback mechanism involving the psychological and/or physical stimuli, the brain and the cardiovascular system,” Ghadri’s co-author Christian Templin continued in the press release. “Perhaps both happy and sad life events, while inherently distinct, share final common pathways in the central nervous system output, which ultimately lead to [this condition]."