14 A single centre retrospective study of patients presenting with acute forms of myocarditis: insights from clinical and cardiac MRI data

Introduction The diagnosis of myocarditis is challenging and is often imprecise despite the availability of contemporary diagnostics such as cardiovascular magnetic resonance (CMR) imaging. We aimed to detect associations between baseline characteristics and CMR features in patients with acute myocarditis. Methods CMR reports of all patients enrolled to the biorepository of a larger tertiary referral centre (Barts BioResource) were interrogated with a natural language processing algorithm to identify individuals with elevated myocardial T2 signal, indicating oedema. Cases not in keeping with a clinical definition of acute myocarditis and those with a known diagnosis of a non-inflammatory form of cardiomyopathy were excluded. Age, sex, body mass index (BMI), peak high sensitivity Troponin T, peak C-reactive protein (CRP), presenting symptoms, and baseline left ventricular ejection fraction (LVEF) on transthoracic echocardiogram (TTE) were collected. CMR outcomes included LVEF, and late gadolinium enhancement (LGE), with the extent of LGE quantified by the number of affected segments. Multivariate analyses were completed evaluating baseline variables and their association with CMR LVEF and LGE adjusting for age, sex, and time to CMR. A sensitivity analysis additionally adjusting for BMI and cardiovascular risk factors was performed. All analyses were completed in Python 3.7. Results Cohort characteristics are summarised in table 1. A total of 127 patients with acute myocarditis were identified of whom 118(93%) had a presentation with chest pain and/or shortness of breath but only 21(18%) of this group had a preceding viral syndrome. Clinical signs of heart failure were detected in 24(21%), 43(34%) were white British, 15(12%) were Asian and 12(9%) were black. Age ranged from 17 to 75 years with a bimodal age distribution for women and 81(64%) males (mean age 36 years) (figure 1). Left ventricular LGE was found in 118(93%) patients with a biventricular LGE pattern in 5(4%) and a non-ischaemic LGE pattern in 115(98%). In the multivariate analyses, the highest tertile of peak troponin was associated with higher LGE (beta=1.90, 95% CI 0.20 to 3.59 segment and P = 2.9 x 10–2) reflecting more segments with LGE and a lower LVEF (beta=-6.96, 95% CI -12.78 to – 1.15% and P = 0.02) (table 2). Adjusting for BMI and cardiovascular risk factors to the model minimally attenuated effect sizes although confidence intervals were much wider due to the limited sample size. Conclusions In this cohort of patients with acutely presenting myocardial inflammation, the severity of myocardial injury indicated by peak troponin was independently associated with markers of adverse CMR outcomes manifested by a greater extent of LGE and lower LVEF, highlighting its prognostic role in the recovery from acute myocarditis. The heterogeneity in clinical presentation and character of injury also underscores the need to stratify these patients and to better understand long-term outcomes. Conflict of Interest None