Heart valve abnormality is associated with malignant arrhythmias

Mitral annular disjunction, MAD, is a heart abnormality in which the mitral valve attachment 'slides'. In recent years, the condition has been linked to an increased risk of severe cardiac arrhythmias. Until now, it has not been known whether the risk of arrhythmias disappears if MAD is surgically corrected.

MAD is often associated with a heart disease called mitral valve prolapse, which affects 2.5 percent of the population and causes one of the heart's valves to leak. This can lead to blood being pumped backwards in the heart, causing heart failure and arrhythmias. The disease can cause symptoms such as shortness of breath and palpitations.

Followed patients after surgery

In the current study, researchers at Karolinska Institutet investigated the risk of cardiac arrhythmias in 599 patients with mitral valve prolapse who underwent heart surgery at Karolinska University Hospital between 2010 and 2022. 16 percent of the patients also had the cardiac abnormality MAD.

"We have been able to show that people with MAD have a significantly higher risk of suffering from ventricular arrhythmias, a dangerous type of heart rhythm disorder that in the worst case can lead to cardiac arrest in a subset of patients," says Bahira Shahim, associate professor at the Department of Medicine, Solna, Karolinska Institutet and cardiologist at Karolinska University Hospital.

People with MAD were more likely to be female and were on average eight years younger than those without MAD. They also had more extensive mitral valve disease. Although the surgery was successful in correcting MAD, these patients had more than three times the risk of ventricular arrhythmias during five years of follow-up compared to patients without preoperative MAD.

"Our results show that it is important to closely monitor patients with this condition, even after a successful operation," says Bahira Shahim.

Investigating several hypotheses

The study has led to new hypotheses that the researchers are now investigating further. One hypothesis is that MAD causes permanent changes in the heart muscle over time. Another is that MAD is a sign of an underlying heart muscle disease. The researchers are now continuing to study scarring in the heart using MRI (magnetic resonance imaging) and analyse tissue samples from the heart muscle.

The research was led by cardiologist and associate professor Bahira Shahim in close collaboration with Magnus Dalén, associate professor at Karolinska Institutet and cardiac surgeon at Karolinska University Hospital, and Klara Lodin, PhD student at Karolinska Institutet. It was financed by ALF funds, the Swedish Heart-Lung Foundation, the Swedish Research Council, the Swedish Society for Medical Research, the Swedish Society of Medicine and Karolinska Institutet.