Cardiac Changes in FOP

Patients with ACVR1R206H mutations have an increased prevalence of cardiac conduction abnormalities on electrocardiogram in a natural history study of FOP

Orphanet Journal of Rare Diseases recently published "Patients with ACVR1R206H mutations have an increased prevalence of cardiac conduction abnormalities on electrocardiogram in a natural history study of Fibrodysplasia Ossificans Progressiva."

As a service to the FOP community, Dr. Ed Hsiao, University of California-San Francisco, along with authors of the article, have provided the following to further educate the FOP community about the July 2020 article.

Although we know a lot about FOP and its effects on the body, there remains a lot to be learned. As part of the Natural History Study (NHS) sponsored by Clementia Pharmaceuticals, an Ipsen Company, our team found that some patients with FOP showed asymptomatic (changes that showed or caused no detected clinical symptoms) changes in electrocardiograms (ECGs) that record the electrical activity of the heart.

We reviewed the ECGs in people with FOP enrolled in the NHS and compared them to published information from the general population. We found that asymptomatic changes in ECGs were detected more frequently in patients with FOP as compared to age-matched healthy populations that were previously published. These ECG changes did not appear to be related to scoliosis, chest wall deformities, or changes in pulmonary function and are unlikely to be caused by the extra bone from the heterotopic ossification in the chest, although this cannot be completely excluded.

It is important to remember that ECG findings have not been considered a clinical problem in FOP and our research findings do not change that premise. The electrical activity changes we saw were asymptomatic, were not considered severe, and did not warrant clinical intervention. 

In addition, echocardiograms (ultrasound images of the heart) showed that some patients with FOP can have structural cardiac findings. These findings were unrelated to the ECG changes and are also of uncertain meaning, as most were considered mild or were asymptomatic. Previous smaller studies have not identified echocardiographic findings in FOP patients. Our analysis does not identify if structural changes occur more frequently in patients with FOP, or how the FOP mutations might lead to cardiac changes, if at all. We also don’t know if these findings change the risk for patients with FOP. However, these findings provide an important basis for future research to better understand these questions.

Although the clinical significance of the asymptomatic findings on ECGs and echocardiograms remain unclear, knowing that these changes can be present is particularly important since some patients may get ECGs as part of their regular care or as a required test in clinical research trials. For patients in whom these ECG changes are found, or have clinical signs of heart symptoms, formal evaluation by a cardiologist may be appropriate and should be done in coordination with your doctor.

We want to express our thanks to everyone who participated in the Natural History Study (NHS). It was only through this coordinated effort that we were able to identify and begin to understand potential effects of FOP outside of the skeleton.

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