A 56-year-old man was admitted with exercise-triggered ventricular tachycardia (VT) of left bundle branch block morphology and inferior axis at 214 bpm. He had a strong family history of sudden death and heart transplantation.
Electrocardiogram showed low voltages in limb leads, inferolateral T-waves inversion, and normal cardiac conduction. Coronary angiogram was normal.
Cardiac magnetic resonance (CMR) showed a mildly dilated right ventricle (RV: 116 mL/m2), with moderate dysfunction (RV ejection fraction of 37%) associated with regional free wall akinesia and dyskinesia and apical hypokinesia. The left ventricle (LV) globally had normal function and volumes but showed areas of late gadolinium enhancement and lateral and inferior wall thinning (Panels A–D, Supplementary data online).
The 18F-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) demonstrated a hypermetabolic focus in the inferior LV and apex compatible with cardiac sarcoid. Consequently, prednisone (0.5 mg/kg/day p.o.) was started with remission of inflammation on follow-up imaging (Panels E–H). A defibrillator was implanted and betablockers were introduced. Despite the absence of detectable inflammation, VT recurred and was terminated by anti-tachycardia pacing 16 months later.
Genetic testing yielded a plakophilin2 (PKP2) pathogenic variant (p.Thr50SerfsTer61). Cardiac biopsy was inconclusive.
Considering all clinical, radiological, histological, genetic data, and family history along with the reach of definite arrhythmogenic right ventricular cardiomyopathy diagnosis per 2010 Task Force criteria, the most plausible diagnosis is arrhythmogenic cardiomyopathy (ACM). The inflammatory PET/CT pattern might correspond to the inflammatory phase described in the pathophysiology of ACM, mainly reported among desmoplakin (DSP) carriers. Interestingly, inflammation remitted but the respective roles of corticoid treatment and of the natural course of the disease itself remain unclear. To our knowledge, this is the first report capturing myocardial inflammation as a reflect of LV involvement in ACM using PET/CT in a patient carrying a disease-causing PKP2 variant.
In the figure, late gadolinium enhancement (arrows) at a subepicardial, transmural, and meso-myocardic level on basal, mid-ventricular, and apical segments is depicted in the CMR viability images at baseline in Panel A (two-chamber view), Panel B (four-chamber view), and Panel C (short-axis view); in Panel D short-axis cine steady-state free procession is also provided for comparison. Hypermetabolic focus in the apex and inferior left ventricle (arrows) on baseline PET/CT is presented in Panel E (two-chamber view) and Panel F (four-chamber view) and its resolution at 8-month follow-up is presented in Panel G (two-chamber view) and Panel H (four-chamber view). Remission of inflammation on PET/CT remained at 15-month follow-up.
Supplementary data are available at European Heart Journal - Cardiovascular Imaging online.
