American College of Cardiology

Jan 17, 2025

New guidance proposed for the diagnosis and treatment of acute myocarditis in adults addresses two key gaps with a four-part staging system — never before proposed for myocarditis — and a five-step care pathway. The American College of Cardiology’s streamlined decision-making framework is spelled out in the ACC Expert Consensus Decision Pathway on Strategies and Criteria for the Diagnosis and Management of Myocarditis, published online in the Journal of the American College of Cardiology. Mark Drazner, MD, MSC, clinical chief of cardiology at UT Southwestern Medical Center in Dallas, and chair of the document’s writing committee, told Medscape Medical News the proposed four-stage framework is similar to the stages in the latest heart failure guideline: Stage A for people who are at risk for myocarditis; Stage B — a new classification — “asymptomatic” disease, but with evidence of myocardial inflammation; Stage C symptomatic; and Stage D advanced — hemodynamic or electrical instability requiring intervention. “This is the first time four-step staging has been proposed in myocarditis, so there’s a lot of work to be done to understand what the various stages mean and how do people progress from the stages, but it really sets the stage for what we think is a new approach to assessing patients with myocarditis,” he said. Five-Step Care Pathway Drazner summarized the pathway components. Step 1: Recognition. This step highlights the three classic myocarditis symptoms — some type of chest pain, a manifestation of heart failure, or a presentation related to arrhythmia, such as syncope or palpitations. “It doesn’t have to be all three,” he pointed out. Step 2: Triage. Included here are practical recommendations on when to refer to an advanced heart failure center. That’s a key question clinicians have, he said, and “we’ve provided very concrete, clinically relevant recommendations.” Step 3: Pivotal diagnostic tests. One test is the gold standard but invasive endomyocardial biopsy. The other is noninvasive cardiac MRI. “That concept may be somewhat new to some clinicians — the importance of cardiac MRI in this role.” The recommendations also address the common question of who needs and doesn’t need a biopsy. Step 4: Treatment. The recommendations address which patients should get immunosuppression. Drazner noted there was no consensus on the writing committee on this issue, and some of that came from what could be a European-United States divide, he said. “We were transparent about where there was no consensus.” However, the recommendations provide practical recommendations where there was consensus on who needs immunosuppression. Step 5: Longitudinal surveillance. The guidance emphasizes that the surveillance should not stop “even if at 2 or 3 weeks they feel asymptomatic,” Drazner said. “We recommend they have longitudinal surveillance at an early timepoint, at 2-4 weeks, and then a later timepoint at 6 months with, for example, imaging modalities.” There have been no universally recognized surveillance timelines for myocarditis, at least in the United States, he said. The guidance also weighs in on the common question clinicians get on when the patient can return to sports or strenuous physical activity. “Return to strenuous physical activity is guided by a follow-up CMR [cardiac magnetic resonance], 24-hour monitoring for arrhythmia, and exercise testing, typically at 6 months after diagnosis,” the report stated. “In some athletes, these assessments can be made as early as 3 months after the initial episode of myocarditis for consideration of return to competitive sports.” Genetic Testing: ‘Pushing the Envelope’ Currently, genetic testing for all patients is far from routine, Drazner explained. “The writing committee did feel that genetic testing should be incorporated broadly in screening patients to see if they may have a variant in a gene related to cardiomyopathy in particular. Its usage is an evolving field and kind of pushing the envelope.” Some parts of the proposed guidance will be controversial, Drazner acknowledged, including the concept of “asymptomatic” disease and the trajectories of how people move among the stages. Those concepts should spark continued research, he said. Drazner pointed out that state-level data included in the committee’s report show large gaps in myocarditis outcomes between racial groups and that mortality rates are particularly high for Black men and women. The additional surveillance called for in these recommendations could pose a significant challenge for the underinsured or uninsured, people of color, and those with less access to care, he said. “By providing these recommendations, we do hope that will help with providing insurance overall in understanding the importance of these follow-up scans,” he added. Drazner reported no relevant financial disclosures. Other committee members reported financial relationships with companies including Abiomed, Alexion, AstraZeneca, Bristol Myers Squibb, Cantargia, Johnson & Johnson, Pfizer, and Roche.