A 38-year-old woman was transferred from a rural hospital to our centre for further investigation and management of recurrent myocarditis. Her initial diagnosis of myocarditis had been established 11 months prior, in March 2021, after presenting to a district hospital with intermittent paroxysms of sharp non-exertional chest pain and a mildly elevated troponin level (20 ng/L). She was haemodynamically stable with unremarkable physical examination. Of note, she did not have any palmoplantar keratoderma or ‘woolly’ hair. There was no significant past medical history, and there was no family history of sudden cardiac death or cardiomyopathy. Further investigations including 12-lead electrocardiogram (ECG) and computed tomography (CT) pulmonary angiogram were all normal. A transthoracic echocardiogram was performed which demonstrated normal biventricular size and function without evidence of valvular disease or a significant pericardial effusion. A CT coronary angiogram demonstrated no evidence of coronary artery disease and a calcium score of zero. She was commenced on colchicine (500 mcg BD) for management of presumed mild idiopathic myopericarditis. In the 11 months since her initial presentation, she had represented with several flares of myocarditis with significant troponin elevations (>500 ng/L). These flares were commonly asymptomatic, detected on surveillance troponin testing completed during routine follow-up. A cMRI completed in October 2021 revealed mildly increased signal on T2-weighted imaging, together with corresponding subepicardial delayed enhancement of the anterior myocardium which was judged at the time to be consistent with myocarditis (). Ventricular systolic function was normal with normal wall thickness. Due to the relapsing–remitting pattern to her disease, she was commenced on prednisone 50 mg daily and transferred to our centre for further investigation. A repeat cMRI (February 2022) demonstrated subtle improvement in the previously noted anterior delayed enhancement; however, note was made of extensive near transmural delayed enhancement of the anterior–lateral myocardium with mild associated hypokinesis but without evidence of active inflammation on T2-weighted imaging (), suggestive of a previous inflammatory/fibrotic process without evidence of active disease. Screening tests for an underlying systemic causes including autoimmune or connective tissue diseases including ANA, ENA, dsDNA, RF, anti-CCP, ANCA, and serum ACE level were negative. Similarly, there was no evidence of viral or other infective causes of the patient’s symptoms. Positron emission tomography (PET)-CT demonstrated no active myocardial or extracardiac inflammation and specifically no evidence to suggest active sarcoidosis. Myocardial biopsy was considered but not pursued at this time as believed to be low yield due to the lack of active inflammation. Given the recurrent nature of her myocarditis as represented by her significant troponin elevation, immune suppression with azathioprine 50 mg daily was commenced, with weaning prednisone at time of discharge. Despite combined azathioprine and colchicine, the patient was readmitted with a further asymptomatic flare of myocarditis when the prednisone was weaned to 40 mg daily with a recurrent elevation in troponin (1984 ng/L). Given the refractory nature of her recurrent myocarditis, the decision was made to trial an interleukin-1 receptor antagonist (anakinra 100 mg via sci daily). A single dose of IV methylprednisolone (1000 mg) was also administered. A timeline of the patients’ therapies and flares of disease is presented in. Repeat cMRI 1 month later showed significant progression of late gadolinium enhancement (LGE) with extensive near circumferential ring-like subepicardial delayed enhancement of the LV myocardium () with increased myocardial signal on T2-weighted imaging indicative of active inflammation. Left ventricular systolic function was at the lower limits of normal, with normal chamber volumes. The combination of MRI findings on this study was recognized to be consistent with a genetically mediated ACM suspicious for DSP. Endomyocardial biopsy was performed at this time; however, the sampled region was normal histologically. During this admission, cardiac telemetry detected short runs of non-sustained ventricular tachycardia (NSVT). An electrophysiology study was negative for inducible VT. A loop recorder was implanted to monitor for further arrhythmia. Cardiac genetic testing was performed and confirmed the presence of a likely pathogenic truncating variant in the DSP gene (DSP p.Ile950Asnfs*3, c.2848dup) located within G1, constitutive non-sense–mediated mRNA decay (NMD)-competent region. With the intention of preventing further inflammatory myocardial damage, the patient was commenced on oral methotrexate as a long-term immunosuppressant therapy. At follow-up 3 months post-discharge, the patient was noted to have multiple runs of asymptomatic NSVT on interrogation of her loop recorder. Given the genetic diagnosis, the high-risk features on CMR, and documented NSVT, the patient underwent insertion of a primary prevention ICD for DSP-mediated ACM.