Myocarditis with Immune Checkpoint Blockade

In their discussion of fulminant myocarditis and complete heart block during immune checkpoint therapy, Johnson et al. do not discuss the possible role of circulating anticonductive tissue autoantibodies (ACTA) in the pathogenesis of the sudden heart block and myocarditis.1 Since it is not known which autoantigens (other than troponin I, which was tested by the authors) could be involved in such a condition, it would be interesting to recheck the patients’ serum for the presence of circulating ACTA using an indirect immunofluorescence assay, as described by our group.2 A possible immune response against the conductive system is suggested by the reported lymphocytic infiltrate involving the cardiac sinus, the atrioventricular node, and the esophageal muscle. In our study, the patient with circulating ACTA had not only heart block but also intestinal pseudo-obstruction, with the latter probably caused by an impairment in the “gut pacemaker” and intestinal conductive system.3