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Fatal arrhythmogenic right ventricular cardiomyopathy in 2 related subadult chimpanzees (Pan troglodytes)

Cardiovascular disease is increasingly recognized as an important cause of morbidity and mortality in captive chimpanzees (Pan troglodytes). This report records 2 cases of sudden cardiac death in closely related subadult captive chimpanzees with marked replacement fibrosis and adipocyte infiltration of the myocardium, which resemble specific atypical forms of the familial human disease arrhythmogenic right ventricular cardiomyopathy. Changes were consistent with left-dominant and biventricular subtypes, which are both phenotypic variants found within human families with familial arrhythmogenic right ventricular cardiomyopathy. Previously reported fibrosing cardiomyopathies in chimpanzees were characterized by nonspecific interstitial fibrosis, in contrast to the replacement fibrofatty infiltration with predilection for the outer myocardium seen in these 2 cases. To the authors' knowledge, this case report is the first to describe cardiomyopathy resembling arrhythmogenic right ventricular cardiomyopathy in nonhuman primates and the first to describe left-dominant arrhythmogenic cardiomyopathy-type lesions in an animal.

Arrhythmogenic cardiomyopathy: etiology, diagnosis, and treatment

Arrhythmogenic right ventricular cardiomyopathy (ARVC) has a prevalence of at least 1 in 1000, is a leading cause of sudden cardiac death in people aged < or =35 years, and accounts for up to 10% of deaths from undiagnosed cardiac disease in the <65 age group. The classic form of the disease has an early predilection for the right ventricle, but recognition of left-dominant and biventricular subtypes has prompted proposal of the broader term arrhythmogenic cardiomyopathy. The clinical profile of the disease bridges the gap between the cardiomyopathies and inherited arrhythmia syndromes. The early "concealed" phase is characterized by propensity toward ventricular tachyarrhythmia in the setting of well-preserved morphology, histology, and ventricular function. As the disease progresses, however, myocyte loss, inflammation, and fibroadiposis become evident. Up to 40% of cases harbor rare variants in genes encoding components of the desmosome, specialized intercellular junctions that confer mechanical strength to cardiac and epithelial tissue, and may also participate in signaling networks. Phenotypic heterogeneity and the nonspecific nature of associated features complicate clinical diagnosis, which requires multipronged cardiovascular investigation rather than a single test. Development of a prospectively validated risk-stratification algorithm for the full disease spectrum remains the foremost clinical challenge.