For patients with acute myocarditis, follow-up cardiac magnetic resonance (CMR) imaging at 6 months after the original CMR provides an evolution of cardiac involvement to evaluate prognosis, according to study results published in the Journal of the American College of Cardiology.
The aim of this study was to assess changes in the myocardial tissue from the first CMR to the follow-up and to evaluate how these changes affect prognosis for patients with acute myocarditis. Data came from the Italian multicenter study on acute myocarditis (ITAMY), which analyzed the overall prognostic value of CMR in patients with acute myocarditis.
Researchers used baseline CMR to diagnose a patient with acute myocarditis, and they used 6-month follow-up CMR to evaluate progress of the condition and assess prognosis. Clinical follow-up examinations included assessment for occurrence of resuscitated cardiac arrest, ventricular assist device, transplantation, implantable cardioverterdefibrillator shock, heart failure (HF) hospitalization, and cardiac-related death.
Of the 187 patients who completed the protocol, 82 were men; the mean age was 33±13 years old; and the mean weight was 78±14 kg. Median time to second CMR was 177 days. Researchers analyzing the findings from the first CMR showed that myocardial edema was found in all patients and late gadolinium enhancement (LGE) was found in 96% of patients. At follow-up CMR, myocardial edema was found in 16% of patients and LGE was found in 86% of patients. After 6 months, 11% of patients were free from both myocardial edema and LGE, 16% had myocardial edema and LGE, 73% had LGE without myocardial edema, and persons who had myocardial edema without LGE at baseline had complete recovery by the follow-up.
Overall, by the follow-up CMR, there was a significant decrease in myocardial segments with edema (P =.02) and a significant decrease in LGE (P <.0003). Late gadolinium enhancement completely disappeared in 10% of the patients, was decreased in 46% of the patients, remained unchanged in 30% of the patients, and increased in 14% of the patients. Clinical follow-up questionnaires had a median time frame of 7 years and showed that 22 patients had cardiac events, including 8 major cardiac events and 14 HF hospitalizations.
Kaplan-Meier survival curves indicated patients with LGE without edema at the follow-up CMR had a worse prognosis when compared with patients with LGE and edema (P <.0001). These analyses also indicated that patients with an increase in LGE at the follow-up CMR had a worse prognosis when compared with patients with a decrease or unchanged late gadolinium enhancement (P =.02). Regression analysis indicated that at the follow-up CMR midwall septal pattern of LGE (P =.028) and LGE without edema (P =.008) were independent predictors of cardiac events.
Limitations of this study include not evaluating T1 and T2 measurements to assess healing from inflammation and only including patients with preserved ejection fraction and infarct-like presentation that might limit generalizability to patients with HF or arrhythmia.
The researchers concluded that “comparing CMR images after 6 months with those obtained during the first week after the onset of symptoms allows assessment of the evolution of myocardial edema. In some patients, LGE disappears during this interval, indicating that its early appearance does not imply irreversible myocardial damage.”
Aquaro GD, Habtemicael YG, Camastra G, et al. Prognostic value of repeating cardiac magnetic resonance in patients with acute myocarditis. J Am Coll Cardiol. 2019;74(20):2439-2448.