Clinical Description
Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a primary cardiomyopathy that is often diagnosed after an individual presents with arrhythmia findings. Presenting manifestations include heart palpitations, syncope, or even sudden death. ARVC typically presents in adults (mean age of first presentation in one large cohort study was 36 ± 14 years [Groeneweg et al 2015]), although it may less commonly be seen in children, most often during the late second decade.
ARVC typically affects the right ventricular apex, the base of the right ventricle, and the right ventricle outflow tract. The arrhythmias in ARVC most frequently arise from the right ventricle and have left bundle branch block morphology. The disease is progressive and is characterized by fibrofatty replacement of the myocardium. Pathology in ARVC may also extend to involve the left ventricle, resulting in regional left ventricular dysfunction.
Note: There is a movement within clinical cardiology to merge ARVC with other arrhythmogenic cardiomyopathies because the left ventricle can become involved, or even become predominantly involved, especially in individuals with DSP pathogenic variants; left ventricular involvement has also been reported in individuals with variants in genes encoding other desmosomal proteins (e.g., DSC2) that were previously associated with ARVC. The 2010 Task Force Criteria (see Diagnosis) are still used to establish a clinical diagnosis of ARVC [Marcus et al 2010], and these criteria do not incorporate other arrhythmogenic cardiomyopathies, leading to potential underdiagnosis. An international expert panel convened to reevaluate the diagnostic approach to arrhythmogenic cardiomyopathies and developed new criteria, the Padua Criteria [Corrado et al 2020]. There are ongoing studies to evaluate the proposed Padua Criteria in larger cohorts. Readers should be aware of the potential overlap/differentiation between ARVC and other arrhythmogenic cardiomyopathies.
Progression. The four described stages of ARVC are the following [Te Riele et al 2021, Wallace & Calkins 2021]:
- 1.
The concealed phase is the earliest phase and is without electrical, structural, or histologic changes as typically seen in ARVC. If scar formation is present, it can be so minimal that it goes undetected by cardiac MRI. However, affected individuals might experience sustained ventricular arrhythmias, and there is a potential risk of sudden cardiac death.
- 2.
An overt electrical disorder characterized by symptomatic arrhythmias including palpitations, syncope, and presyncope attributable to ventricular ectopy or sustained or nonsustained ventricular tachycardia
- 3.
Right ventricular failure
- 4.
A biventricular pump failure (resembling dilated cardiomyopathy) [Dalal et al 2006]
Cardiomyopathy in ARVC is not always isolatedto right ventricular involvement. There is evidence that the left ventricle can often become involved as well. The cohort of individuals with ARVC followed by Bhonsale et al [2015] had an overall incidence of left ventricular dysfunction of 14% over the follow-up interval, with 5% experiencing heart failure. In a separate cohort, 55% of individuals with DSP pathogenic variants experienced left ventricular predominant cardiomyopathy [Smith et al 2020].
Arrhythmia. The principal characteristic of arrhythmogenic cardiomyopathies is the tendency for ventricular arrhythmia in the absence of overt ventricular dysfunction. Arrhythmias in ARVC include ventricular tachycardia and ventricular fibrillation. Atrial fibrillation has also been described in ARVC. One recent study identified atrial fibrillation occurring in one in seven individuals with a diagnosis of definite ARVC (by 2010 Task Force Criteria), with atrial fibrillation onset at a median age of 51 years [Baturova et al 2020]. The risk of atrial fibrillation increases with severity of the ARVC phenotype compared to individuals who have an ARVC-related pathogenic variant but do not have clinical manifestations of ARVC (and thus do not meet 2010 Task Force Criteria).
Prognosis. Two long-term studies of individuals with ARVC suggested that survival was greater than 72% at six years following diagnosis. In individuals with ARVC, cardiac mortality and need for transplant are less than 5% [Bhonsale et al 2015, Groeneweg et al 2015]. An individual with a prior history of sustained ventricular tachycardia or fibrillation is at increased risk for subsequent ventricular arrhythmias and sudden cardiac death. Prognosis is worse for individuals with more than one ARVC-related pathogenic variant, with an increased propensity to arrhythmias and progression to cardiomyopathy [Bao et al 2013, Rigato et al 2013, Bhonsale et al 2015, Groeneweg et al 2015].
Prevalence. The prevalence of clinical ARVC is estimated at 1:1,000-1,250 in the general population, although most of this data derives from cohorts of European ancestry [Wallace & Calkins 2021]. The prevalence of ARVC is greater in certain regions; in Italy and Greece (island of Naxos), it can be as high as 0.4%-0.8% [Thiene & Basso 2001].
Diagnosis
Diagnostic criteria for ARVC, initially proposed by an international task force [McKenna et al 1994], were revised by Marcus et al [2010] (full text) to incorporate new knowledge and technology to improve diagnostic sensitivity while maintaining diagnostic specificity. Diagnostic criteria rely on a combination of EKG and signal averaged EKGs, imaging studies that include 2D echocardiography, cardiac MRI or right ventricular (RV) angiography, presence of arrhythmia documented by telemetric monitoring, genetic testing, and family history. Individuals are classified as having a definite, borderline, or possible diagnosis of ARVC based on the number of major and/or minor diagnostic criteria present.
A definite diagnosis of ARVC is established in a proband with the following findings from different categories:
A borderline diagnosis of ARVC is considered in a proband with:
A possible diagnosis of ARVC is considered in a proband with:
Imaging Findings: Global and/or Regional Cardiac Dysfunction and Structural Alterations
Major
Minor
Endomyocardial Biopsy or Autopsy Findings
Major. Residual myocytes <60% by morphometric analysis (or <50% if estimated), with fibrous replacement of the RV free wall myocardium in at least one sample, with or without fatty replacement of tissue
Minor. Residual myocytes 60%-75% by morphometric analysis (or 50%-65% if estimated), with fibrous replacement of the RV free wall myocardium in at least one sample, with or without fatty replacement of tissue
EKG Findings
Repolarization abnormalities
Depolarization/conduction abnormalities
Arrhythmias
Family History and Molecular Genetic Testing
Major
Minor