Assessment of Coronary Inflammation by Pericoronary Fat Attenuation Index in Clinically Suspected Myocarditis with Infarct-Like Presentation

Background: The pathophysiology of angina-like symptoms in myocarditis is still unclear. Perivascular fat attenuation index (pFAI) by coronary computed tomography angiography (CCTA) is a non-invasive marker of coronary inflammation (CI) in atherosclerosis. We explored the presence of CI in clinically suspected myocarditis with infarct-like presentation. Methods: We retrospectively included 15 consecutive patients (67% male, age 30 +/- 10 years) with clinically suspected infarct-like myocarditis who underwent CCTA to rule out coronary artery disease. Right coronary artery (RCA) pFAI mean value was compared with that of healthy volunteers. Results: Mean RCA pFAI value was -92.8 +/- 8.4 HU, similar to that of healthy volunteers (-95.2 +/- 6.0, p = 0.8). We found no correlation between RCA pFAI mean values and peak Troponin I (r = -0.43, p = 0.11) and C-reactive protein at diagnosis (r = -0.25, p = 0.42). Patients with higher pFAI values showed higher biventricular end-systolic volumes (ESV) (p = 0.038 for left and p = 0.024 for right ventricle) and lower right ventricular ejection fraction (RVEF) (p = 0.038) on cardiovascular magnetic resonance. Conclusions: In clinically suspected myocarditis with infarct-like presentation, RCA pFAI values are lower than those validated in atherosclerosis. The correlation between higher pFAI values, higher biventricular ESV and lower RVEF, may suggest a role of pFAI in predicting non-atherosclerotic CI (i.e., infective/immune-mediated endothelialitis).

Automated summary

In patients with clinically suspected myocarditis presenting with infarct-like symptoms, the perivascular fat attenuation index (pFAI) values in the right coronary artery (RCA) were found to be lower than those seen in atherosclerosis. Higher pFAI values were associated with increased biventricular end-systolic volumes and decreased right ventricular ejection fraction on cardiovascular magnetic resonance, suggesting a potential role of pFAI in predicting non-atherosclerotic coronary inflammation.