Q&A: ACC unveils new staging system, decision pathway for myocarditis diagnosis, care
Click Here to Manage Email Alerts
Key takeaways:
- The ACC issued an expert consensus statement on the diagnosis and treatment of myocarditis.
- The document features a new myocarditis staging system and decision pathway for physicians.
The American College of Cardiology recently issued an expert consensus document outlining a novel staging system and decision pathway for the diagnosis, treatment and longitudinal follow-up of patients with myocarditis.
Healio spoke with Mark H. Drazner, MD, MSC, FACC, clinical chief of cardiology at UT Southwestern Medical Center and chair of the document’s writing committee, about the new staging system and the new care decision pathway and how both could improve the management of myocarditis.
Healio: What knowledge gaps in myocarditis diagnosis and management does this expert consensus document intend to fill?
Drazner: There are two knowledge gaps this expert consensus decision pathway intends to fill. The first is a proposed five-step care pathway for the evaluation and treatment of patients with myocarditis. There haven’t been any recent guidelines, at least in the United States, to guide management of patients with myocarditis.
The second is a novel staging classification for myocarditis. We proposed a four-stage model, from stages A to D. It reflects the fact that myocarditis is not a static condition, but rather one with trajectories over time.
Healio: Can you give some background on why the staging system was needed and how you developed it?
Drazner: When we were looking at conceptual models to describe the progression of patients with myocarditis, we recognized similarities to what had previously been proposed for patients with HF. Specifically, we thought the four-stage model in the ACC/American Heart Association/Heart Failure Society of America Guidelines for HF could be adapted to patients with myocarditis. The four stages are the following.
Stage A: At-risk for myocarditis. These are people who have risk factors for developing myocarditis but are without evidence of myocarditis.
Stage B: Asymptomatic. These are people who don’t have symptoms but have evidence of myocarditis, whether that be on cardiac MRI, endomyocardial biopsy, or, in the right clinical context, an elevated high-sensitivity cardiac troponin level.
Stage C: Patients who have symptomatic myocarditis. They would have symptoms as well as the evidence of myocarditis described for stage B.
Stage D: Advanced myocarditis. These are people with more severe manifestations of the condition who have either hemodynamic or electrical instability requiring intervention.
Healio: What are some of the common causes of myocarditis?
Drazner: In terms of risk factors, there are three broad categories one can consider. First, various viruses can cause myocarditis. Second, myocarditis in the context of an autoimmune condition. Third, toxins and various substances that one could ingest such as illicit drugs, but also prescribed medications including those agents used in cancer therapy such as immune checkpoint inhibitors.
Healio: What are some of the current barriers to adequate myocarditis diagnosis and care?
Drazner: The first barrier to myocarditis care is recognition of the syndrome because it can present in a variety of ways. In the expert consensus decision pathway, we emphasized the three classic symptoms of myocarditis: chest pain, HF and/or arrhythmia. Importantly, these symptoms may lead patients to present to not only cardiologists but to their primary care physician or the ED, amongst many other settings. Another challenge is that myocarditis can present in a more subtle manner which could be challenging to diagnose, even for a more specialized or experienced physician.
Another barrier is that even when symptoms resolve, patients need further longitudinal follow-up, meaning that care needs to continue. We proposed a strategy on how to provide that longitudinal follow-up, recommending two additional imaging tests, one at 2 to 4 weeks, and then one at 6 months. One key point emphasized in the current expert consensus decision pathway is that patients with myocarditis do require longitudinal care, even if their symptoms resolve.
Healio: Could you give a brief walkthrough of the new five-step care pathway that is suggested in this document?
Drazner: The five-step care pathway starts with step one: “Recognition.” As previously mentioned, myocarditis can present with three classic symptoms related to either chest pain, HF or electrical disturbances. Typically, electrical disturbances would be either feeling palpitations or some type of presyncope or syncope. Since patients with HF can present with a variety of manifestations, it can be subtle. For example, patients can have gastrointestinal symptoms related to low cardiac output, and those symptoms may not immediately be recognized as a manifestation of right-sided HF. Patients may also present with dyspnea or just overt symptomatic HF. The first step is recognition and being aware of these three classic symptoms.
The second step was what we called “Triage.” Does the person need hospitalization? Can the patient be hospitalized at their current facility, or do they need to be referred to an advanced HF center? Typically, an advanced HF center is one that could provide therapies like mechanical support or heart transplant. Also in triage is deciding whether you need to do something emergently to stabilize the patient from an arrhythmia or circulatory support standpoint.
The third step was what we called “Pivotal diagnostic tests.” We classified two diagnostic tests as pivotal. The first was cardiac MRI and the second was endomyocardial biopsy. Endomyocardial biopsy would be the gold standard. It gives you the actual histopathology, but there are some risks of the procedure. One of the exciting areas in the field is the development of cardiac MRI as a viable, noninvasive strategy to diagnose myocarditis. We provided considerable details about the use of cardiac MRI for the diagnosis of myocarditis, which were taken from the updated Lake Louise Criteria.
A lot of clinicians might think that a high-sensitivity troponin assay, useful for the diagnosis of MI or ACS, would be a pivotal test. However, in myocarditis, you can have a non-elevated troponin and still have myocarditis, we did not consider troponin to be a pivotal diagnostic test for this condition.
The fourth step is “Treatment,” and we focused on pharmacological treatment. Of course, people want to know when to provide immunosuppressive therapy, which is different from the therapies you typically would administer to a patient with chronic HF or acutely decompensated HF. In the document, we listed the etiologies of myocarditis where one should treat with immunosuppression. The one that most clinicians fear is giant cell myocarditis, which can rapidly progress to death and does require treatment beyond steroid therapy. In fact, when you see patients with myocarditis who are ill, that is always in the back of your mind. Are you missing one of those diagnoses, like giant cell myocarditis, eosinophil myocarditis or another condition that requires therapy distinct form the usual guideline-directed medical therapy you would otherwise use to treat a patient with new-onset HF?
The fifth step is “Longitudinal follow-up” which, as mentioned previously, includes repeat cardiac imaging at 2 to 4 weeks, and again at 6 months. Another important aspect in terms of longitudinal follow-up is related to the increasing evidence of a genetic contribution in a minority of patients with myocarditis. The writing committee felt that it was reasonable to offer genetic counseling and testing to all patients who have myocarditis. The rational for this recommendation is that a genetic predisposition in a cardiomyopathy gene could have implications not only for the patient, but also the family.
In addition to repeat imaging and genetic counseling and testing, the other point we focused on was when it was safe to return to “strenuous physical activity,” which would include competitive sports. There is an association of myocarditis with sudden death in athletes, and so we provided some guidance on how to assess when it is safe for athletes to return to competition.
Healio: Do any knowledge gaps remain in the diagnosis and management of myocarditis that are not addressed in this document?
Drazner: Yes, many important gaps do remain.
Now that we have proposed this four-stage myocarditis classification model, an important gap is understanding how people move between the stages. A particularly novel component of the four stages was stage B or “asymptomatic myocarditis.” Studies are needed to understand how common that condition is; how commonly that progresses to higher stages; and how good are our tests to make that diagnosis?
Another major gap is in the treatment domain. Many recommendations were made by expert consensus because we do not have large, randomized trials to guide decision-making. Likewise, the recommendations provided for longitudinal follow-up, including genetic testing, were based on expert consensus recommendations rather than clinical trial data.
There also are gaps in terms of ensuring adequate access to the needed care for patients with myocarditis. For example, if you look at mortality rates, there are large differences between white and Black patients with myocarditis in the United States, with higher rates among Black patients. We need to ensure that adequate follow-up is available for all patients who have this condition.
Healio: Anything else you would like to add?
Drazner: If I was a clinician with a patient with myocarditis, one important question I would have is when do I need to call for help and transfer my patient for higher level of care? Sometimes the condition can progress rapidly, and you want to make sure that you are prepared to handle those circumstances. We provided specific recommendations on when patients should be referred to an advanced HF center. That is important because there are certain therapies not available at every medical center or every hospital but are available at advanced HF centers.
References:
- American College of Cardiology issues guide for diagnosing and managing myocarditis. https://www.acc.org/Latest-in-Cardiology/Articles/2024/12/10/20/44/acc-issues-guidance-for-diagnosing-and-managing-myocarditis. Published Dec. 10, 2024. Accessed Dec. 30, 2024.
- Drazner MH, et al. J Am Coll Cardiol. 2024;doi:10.1016/j.jacc.2024.10.080.
Collapse
Healio Interviews
Click Here to Manage Email Alerts