Arrhythmogenic right ventricular cardiomyopathy as a cause of unexpected cardiac death in two horses

Abstract

Postmortem and histological examination of the hearts from two horses, a five-year-old Clydesdale gelding and a 15-year-old cob gelding, revealed changes characteristic of arrhythmogenic right ventricular cardiomyopathy. In both cases, on gross examination, the right ventricular endocardium and interventricular septum were almost entirely replaced with a gelatinous yellow fibroareolar tissue. This tissue was histologically a combination of fibrous and adipose tissue that had replaced the normal myofibres and disrupted the Purkinje fibres.

Arrhythmogenic right ventricular cardiomyopathy secondary to adipose infiltration as a cause of episodic collapse in a horse

“…Both animals had significant adipose and fibrous infiltration of the right ventricle wall and interventricular septum wall with disruption of the Purkinje fibres, similar to this case, and a diagnosis of arrhythmogenic right ventricular cardiomyopathy was made. Unlike this case, the horses reported by Freel et al [ 13 ] both had an enlarged right ventricle, but this may reflect the end progression of the disease, given that both of those cases had suffered fatal cardiogenic collapse. The parallels between these changes and pathologies noted in humans and dogs have been discussed at length previously [ 13 ] but it is notable that syncopal episodes are common (52 %) in Boxer dogs with ARVC [ 1 ].…”

“…Unlike this case, the horses reported by Freel et al [ 13 ] both had an enlarged right ventricle, but this may reflect the end progression of the disease, given that both of those cases had suffered fatal cardiogenic collapse. The parallels between these changes and pathologies noted in humans and dogs have been discussed at length previously [ 13 ] but it is notable that syncopal episodes are common (52 %) in Boxer dogs with ARVC [ 1 ]. Left ventricular pathology which was also noted in this case is observed in a small proportion of affected boxer dogs [ 20 ] but greater than 50 % of affected humans [ 2 ] with no specific identified risk factors.…”

“…A comparable abattoir study of non athletic or obese horses has not been recorded. Adipose and fibrous tissue infiltration of the myocardium has been documented previously as a cause of cardiac death in two horses [ 13 ]. One of these horses presented with ventricular tachycardia that was refractory to medical management and progressed to ventricular fibrillation and death; the second horse was found dead in the field.…”

“…In boxer dogs presenting signs include sudden death, ventricular arrhythmias of suspected right ventricular origin, syncope and heart failure [ 1 ]. ARVC due to fibrofatty infiltration has been previously reported in two horses as a cause of cardiac death [ 13 ] although a genetic predisposition has not been identified in equids.…”

Arrhythmogenic Right Ventricular Cardiomyopathy: Considerations from in Silico Experiments

“…These and other characteristics of ARVC have been reviewed in detail elsewhere (Thiene et al, 2007; Basso et al, 2009, 2012; Sen-Chowdhry et al, 2010; Sen-Chowdhry and McKenna, 2012). The disease does not only occur in humans, but has also been described for cats (Fox et al, 2000; Harvey et al, 2005), dogs (Basso et al, 2004; Oxford et al, 2011), and horses (Freel et al, 2010). …”