A complex condition that is not well understood, cardiac sarcoidosis (CS) can affect the electrical pathways in the heart and cause potentially serious irregular heartbeats, known as arrhythmias. In May of this year, the Heart Rhythm Society released the first international guidelines for diagnosing and treating the disease.
A panel co-chaired by David Birnie, MD, of the University of Ottawa Heart Institute, developed these recommendations which will provide much-needed guidance to clinicians who must identify and manage the arrhythmias associated with CS. Because of the condition’s rarity, little data on CS exist, so the guidelines reflect a consensus based on the experiences of those who have followed such patients.
Dr. Birnie’s experience with CS dates back to 2006, when a woman in her 50s came to the Heart Institute with an abnormal heartbeat but with no other signs of heart problems.
A cardiac electrophysiologist and Director of the Heart Institute’s Arrhythmia Service, Dr. Birnie treated the arrhythmia with a pacemaker and thought nothing more of it—until the same patient returned two years later suffering from heart failure. Upon further investigation, it turned out that she had cardiac sarcoidosis.
Why, she asked Dr. Birnie, wasn’t it diagnosed when she first saw him? He had no good answers for her. So he set out to find some.
Today, Dr. Birnie and his collaborators, Pablo Nery, MD (staff electrophysiologist) and Rob Beanlands, MD (Chief of Cardiology and Director of the National Cardiac PET Centre) have established a Cardiac Sarcoidosis Clinic to treat people with the disease and conduct research to learn more about it.
“We’re making progress,” Dr. Birnie said. “Six years ago, we were nowhere.”
Sarcoidosis can attack multiple organs and tissues, most commonly the lungs. It is characterized by the formation of clusters of white blood cells, called granulomas. In cardiac sarcoidosis, these most often form in the heart muscle. The cause is unknown but may involve an over-reaction of the immune system when exposed to a bacteria or virus. It is also thought to have a genetic component.
Sarcoidosis is a rare disease, affecting anywhere from five to 64 people in every 100,000, depending on race, location and other factors. In Canada, roughly 7,000 people may be affected. It is usually a benign disease but can be serious, especially if it involves the heart. Symptoms due to cardiac involvement are present in perhaps 5% of all cases. When not benign, CS can cause enormous harm, up to and including heart failure and sudden death, making early identification and treatment important to ward off such progression.
“We want to find the benign patients and reassure them,” said Dr. Birnie. “And we want to find the more aggressive ones and treat them more aggressively.”
Unfortunately, right now, there is no way to predict who will have a relatively benign disease and whose disease will progress. Imaging techniques, however, may be changing this.
When not benign, CS can cause enormous harm, up to and including heart failure and sudden death
“With PET [positron emission tomography] and MR [magnetic resonance] imaging we are now detecting more patients with this disease than before,” said Dr. Beanlands. “We are studying what characteristics may predict who may get worse and need certain treatments based on the amount of inflammation in the heart.”
Because of the lack of certainty as to how a person’s disease will progress, it is import-ant to treat everyone. Corticosteroids, such as prednisone, are generally given to reduce inflammation in the heart. Inflammation leads to scarring of the heart muscle and, said Dr. Nery, “once it’s scarred, there’s no way back.”
The Cardiac Sarcoidosis Clinic sees all those who fit the criteria for CS—young, generally between the ages of 25 and 45, and with no symptoms of heart disease other than arrhythmia. The clinic has been able to identify patients with CS and track them to assess their response to treatment. The overarching goal of the research is to validate the idea that early identification and treatment can make a significant difference.
The research has three aspects:
- Assessing the frequency of CS among patients with otherwise unexplained arrhythmias.
- Assessing the frequency of CS among patients with sarcoidosis in other areas of their body, particularly the lungs.
- Assessing and improving the use of advanced imaging techniques, such as PET and MRI scanning, to better diagnose and monitor CS.
Because of the small numbers of people involved, the Heart Institute physicians have also spearheaded the Cardiac Sarcoidosis Multicentre Prospective Cohort Study (CHASM-CS), which collects data on patients with the disease from centres across Canada and one in Japan, at Hokkaido University. Hiroshi Ohira, MD, from the Hokkaido site, is training at the Heart Institute as a fellow and has been instrumental in facilitating the international collaboration. The study, set to be completed in 2015, will permit the physicians to better test their hypotheses about CS with larger numbers of patients. The research underway in the Cardiac Sarcoidosis Clinic has positioned the Heart Institute as a centre of reference for the diagnosis and treatment cardiac sarcoidosis, said Dr. Nery.