ACC Offers ‘Practical Document’ for Myocarditis Diagnosis and Care

A new expert consensus decision pathway from the American College of Cardiology (ACC) provides guidance around the management of myocarditis from diagnosis to follow-up.

In light of recent advances in myocarditis care and the lack of a dedicated practice guideline, the document, published online this week in the Journal of the American College of Cardiology, gives practical advice to clinicians tasked with managing these patients, Mark Drazner, MD (UT Southwestern Medical Center, Dallas, TX), chair of the writing committee, told TCTMD.

One of the highlights is a novel four-stage classification system for the condition:

• Stage A (at risk, with patients having or being exposed to risk factors)
• Stage B (asymptomatic but showing evidence of myocardial inflammation)
• Stage C (symptomatic myocarditis)
• Stage D (advanced myocarditis, with hemodynamic or electrical instability requiring intervention)

“This really came to fruition out of the recognition that one could look at myocarditis similarly to other cardiac conditions, like chronic heart failure [HF] or valvular heart disease, [that] have been classified into four stages,” Drazner said. “We thought by creating this four-stage classification, it would be useful and call attention to what we’ll call the trajectories of the condition. It’s not a static condition.”

Laying this groundwork, he added, will allow for research into the various trajectories and potential therapies for each stage.

“Most importantly, I think [the document] hopefully will call attention to myocarditis in the clinical community,” Drazner said, noting that clinicians across specialties—and not just cardiology—encounter these patients.

A Five-Step Pathway

The pathway outlined in the document has five main steps, starting with recognition of the three classic presentations of myocarditis—chest pain, heart failure/cardiogenic shock, and symptoms related to arrhythmias, like palpitations and presyncope or syncope—and the initial workup.

That is followed by triage to determine whether a patient needs to be hospitalized, to be urgently referred to an advanced HF center, or to receive emergent arrhythmia management or circulatory support.

“There should be a low threshold to transfer patients with high-risk features, such as severely reduced ventricular function, symptomatic HF, hemodynamic instability, or electrical instability (either ventricular arrhythmias or heart block),” Drazner et al write.

Pivotal diagnostic testing that includes cardiac magnetic resonance (CMR) imaging and endomyocardial biopsy comes next in the pathway, after which appropriate treatment is provided.

The final step is longitudinal follow-up that includes biomarker testing, echocardiography, CMR, outpatient genetic counseling and testing, and an assessment for a return to physical activity and/or sports.

It’s not a static condition. Mark Drazner

Drazner suggested that the creation of this document was motivated by the difficulty some patients with myocarditis have in getting insurance coverage for these follow-up tests. “Patients present with myocarditis and they’ll have an initial scan, and then the issue is about their ability to get a repeat assessment of their cardiac function both in the short term and over longer-term follow-up to show resolution of myocarditis,” he explained. “Some members of the committee raised the issue that in their experience there’s not been universal coverage afforded to patients to get those follow-up scans.”

In the paper, the authors stress that follow-up of these patients doesn’t end when symptoms resolve and recommend two cardiac imaging studies after the acute issue is addressed—a repeat echocardiogram at 2 to 4 weeks to look for new or progressive deterioration of LV function and, depending on the severity of the initial myocarditis, either a CMR scan or second echocardiogram at 6 months.

In addition to the importance of longitudinal follow-up, Drazner highlighted genetic considerations as a key part of the document. “We propose that all consenting individuals who have myocarditis should be offered genetic counseling and then genetic testing,” he said. “Because of the emerging evidence of the role of genetics, we thought it was reasonable that people with myocarditis should be offered that.”

Knowledge Gaps

The document closes with a discussion of important areas of research needed to fill gaps in knowledge about myocarditis, including the trajectories of the four stages and the impact of social determinants of health on the condition’s development and progression.

The authors say that “international registries for myocarditis are necessary to gather data on a larger scale that enables detection of characteristics and patterns of myocarditis that would not be recognized in single-center studies. A shared international definition of myocarditis with similar diagnostic standards will be paramount to allow for comparability of data.”

Moreover, Drazner said, those registries should be complemented by randomized controlled trials “so that we have a better evidence base for how to treat patients with myocarditis.”

While awaiting further data, this expert consensus decision pathway provides some guidance for clinicians navigating management of this condition, Drazner said. “It was written deliberately for clinicians to provide them a practical document to help them care for patients with myocarditis. I think in that way . . . it would have clinical relevance.”

The document was endorsed by the Heart Failure Society of America; the International Society of Cardiomyopathies, Myocarditis and Heart Failure; and the Myocarditis Foundation.