The many faces of atrioventricular block in myocarditis: a case series and proposed clinical strategy highlighting cardiovascular magnetic resonance–guided diagnosis, device selection, and disease monitoring

Figure 1. Detailed timeline for the presented cases. CMR, cardiac magnetic resonance; MPS, methylprednisolone; MTX, methotrexate; PET, positron emission tomography; PM, definite pacemaker implantation; TTE, transthoracic echocardiography; Troponin max, maximal troponin levels during admission; RV, right ventricle; other abbreviations as in Summary Figure.

AV, atrioventricular; LGE, late gadolinium enhancement; SLE, systemic lupus erythematosus; ICI, immune checkpoint inhibitor.

Figure 2. CMR findings in Case 1, a patient with SLE myocarditis. Baseline CMR demonstrated increased signal intensity basal anteroseptal on T2-weighted turbo spin echo (T2w-TSE), globally increased myocardial T1 and T2 values on mapping, anteroseptal mid, respectively, 1599 and 56 ms, and no late gadolinium enhancement (LGE). CMR imaging after 2 months showed persisting albeit decreased myocardial inflammation with normal T2w-TSE images but slightly elevated T1 and T2 values on mapping (1094 and 53 ms anteroseptal mid, respectively) and no LGE. CMR imaging after 9 months demonstrated complete normalization without signs of myocardial inflammation on T2w-TSE and T1 and T2 mapping and absence of LGE. Abbreviations as in Figure 1.

Figure 3. CMR findings in Case 2, a patient with ICI-induced myocarditis. Baseline CMR showing elevated T1 and T2 values anteroseptal (1047 and 53 ms, respectively) and no LGE, taken together consistent with myocarditis. CMR after 3 months demonstrated complete resolution of myocardial inflammation with normalization of myocardial T1 and T2 values and still no LGE. Abbreviations as in Figure 1.

Figure 4. CMR findings in Case 3, a patient with cardiac sarcoidosis. Baseline CMR and fluorodeoxyglucose positron emission tomography computed tomography (FDG PET-CT) imaging: SFFP cine images showing mildly dilated left ventricle (LV) with wall thinning of the basal septum, multifocally increased signal intensity on T2w-TSE, regionally increased myocardial T1 values anterior/inferior (anteroseptal normal T1 values 994 ms) with diffusely increased T2 values (mean 54 ms, anteroseptal 53 ms), and extensive multifocal nearly transmural LGE matching the areas with increased T1 values. Lastly, FDG PET-CT demonstrating increased tracer uptake in the myocardium consistent with sarcoidosis. Serial imaging with CMR (after 11 months) and PET-CT (after 5 months) showed progressive LV dilatation on SFFP cine images; resolution of inflammation as demonstrated by normalization of T2w-TSE images and normalization of myocardial T1 and T2 values, apart from the artefact caused by the CRT-D (marked with an asterisk); and persistent multifocal pattern of LGE in the same regions as previously. Lastly, FDG PET-CT showed reduced disease activity demonstrated by decreased myocardial FDG uptake. Abbreviations as…

Figure 5. CMR findings in Case 4, a patient with viral myocarditis. Baseline CMR imaging showed increased myocardial T1 and T2 values anteroseptal, anterior, and inferolateral (anteroseptal 1296 and 47 ms, respectively) and no LGE. Follow-up CMR imaging demonstrated complete resolution of myocardial inflammation with normalization of myocardial T1 and T2 values and still no LGE. Abbreviations as in Figure 1.

Figure 6. Proposed expert opinion based strategy for the work-up and treatment of patients with high-degree or complete AV block. CRT-D: cardiac resynchronization therapy-defibrillator; ICD, implantable cardioverter–defibrillator; other abbreviations as in Figure 1.