Physical Address

304 North Cardinal St.
Dorchester Center, MA 02124

Arrhythmogenic Right Ventricular Cardiomyopathy


Arrhythmogenic right ventricular cardiomyopathy (ARVC) is a heritable heart muscle disease characterized by fibrofatty replacement of, predominantly, the right ventricular (RV) myocardium, which predisposes patients to potentially life-threatening arrhythmias and ventricular dysfunction. Affected patients typically present between the second and fourth decade of life with arrhythmias coming from the RV. ARVC is an unusual condition, with an estimated prevalence of 1 in 1000 to 1 in 5000 Caucasian individuals. Approximately 60% of index cases harbor mutations in genes encoding the cardiac desmosome, a structure that provides mechanical connection between cardiomyocytes. The defective mechanical connections in ARVC may structurally be represented by global or regional contraction abnormalities, ventricular enlargement, and/or fibrofatty replacement. As such, accurate evaluation of cardiac morphology and function is essential for ARVC diagnosis and management.

ARVC constitutes a diagnostic challenge for the cardiovascular magnetic resonance (CMR) physician. The variation in shape and contraction patterns of the normal RV complicates identification of early, subtle RV disease. In addition, many imaging centers have little experience with evaluating ARVC, and gaining experience is difficult because of the low prevalence of disease. Missing a diagnosis of ARVC may prove to be fatal, whereas overdiagnosis may lead to therapeutic repercussions in essentially healthy individuals. Despite these challenges, CMR is generally acknowledged to be the “best” noninvasive test for ARVC diagnosis and to distinguish ARVC from other cardiomyopathies. Thus the aim of this chapter is to review current knowledge of ARVC that is useful for CMR interpretation of individuals suspected of this disease. Our emphasis will be on ARVC diagnosis and management, including diagnostic criteria, CMR acquisition/analysis, and common regional morphologic and functional abnormalities in ARVC.

A Historical Perspective on Arrhythmogenic Right Ventricular Cardiomyopathy

The first comprehensive clinical description of ARVC dates back to 1982, when Marcus and colleagues described a cohort of 24 patients with arrhythmias originating from the RV and (right) heart failure. Using echocardiography, angiography, and histologic specimens obtained at surgery, they described ARVC as a regional RV disease with paper-thin RV myocardium, myocardial cell loss, and abundant subepicardial fat. The abnormal RV regions were traditionally thought to be located to the so-called triangle of dysplasia (i.e., RV inflow tract, RV apex, and RV outflow tract [RVOT]). In subsequent years, several ARVC manuscripts have focused on gross or histologic evidence of myocardial cell loss with fibrofatty replacement. It is important to note that these observations were made in tertiary centers, without the advantage of genetic testing and without sensitive diagnostic criteria. Over the last decade, several collaborative efforts in the United States and Europe have significantly enhanced our understanding of (the role of CMR in) ARVC diagnosis, clinical characteristics, and management. These advancements are reviewed here.

Diagnosis of Arrhythmogenic Right Ventricular Cardiomyopathy

Diagnosis of ARVC is challenging because no single modality is sufficiently specific to establish an ARVC diagnosis. Therefore multiple sources of diagnostic information are combined in a complex set of diagnostic criteria. Definite ARVC diagnosis is based on the presence of major and minor criteria encompassing structural, histologic, electrocardiographic, arrhythmic, and family history criteria ( Box 34.1 ). These “Task Force” criteria (TFC) were first established in 1994 and updated in 2010 to improve (1) the specificity of the TFC by including quantitative metrics for diagnosis; and (2) sensitivity of the TFC in individuals who have a high likelihood of inherited/genetic disease. Structural criteria for ARVC diagnosis may be based on echocardiography, angiography, or CMR. However, echocardiographic evaluation of the RV is difficult because of its complex geometry, and a recent study has shown that echocardiographic evaluation of subtle RV changes may be unreliable. In addition, angiography is invasive and should not be employed as a first-line screening test for ARVC. In contrast, CMR allows for noninvasive multiplane morphologic and functional evaluation, as well as tissue characterization in a single investigation, and has emerged as the imaging modality of choice in ARVC.

Box 34.1
Modified from Marcus FI, McKenna WJ, Sherrill D, et al. Diagnosis of arrhythmogenic right ventricular cardiomyopathy/dysplasia: proposed modification of the task force criteria. Circulation . 2010;121:1533–1541.
Revised 2010 Task Force Criteria for Arrhythmogenic Right Ventricular Cardiomyopathy

Global or Regional Dysfunction and Structural Alterations

Major

Two-Dimensional Echocardiography Criteria

  • Regional RV akinesia, dyskinesia, or aneurysm and one of the following measured at end diastole:

    • PLAX RVOT ≥32 mm (PLAX/BSA ≥19 mm/m 2 ), or

    • PSAX RVOT ≥36 mm (PSAX/BSA ≥21 mm/m 2 ), or

    • Fractional area change ≤33%

Cardiovascular Magnetic Resonance Criteria

  • Regional RV akinesia or dyskinesia or dyssynchronous RV contraction and one of the following:

    • RV EDV/BSA ≥110 mL/m 2 (male) or ≥100 mL/m 2 (female), or

    • RV ejection fraction ≤40%

Right Ventricular Angiography Criteria

  • Regional RV akinesia, dyskinesia, or aneurysm

Minor

Two-Dimensional Echocardiography Criteria

  • Regional RV akinesia or dyskinesia or dyssynchronous RV contraction and one of the following measured at end diastole:

    • PLAX RVOT ≥29 to <32 mm (PLAX/BSA ≥16 to <19 mm/m 2 ), or

    • PSAX RVOT ≥32 to <36 mm (PSAX/BSA ≥18 to <21 mm/m 2 ), or

    • Fractional area change >33% ≤40%

Cardiovascular Magnetic Resonance Criteria

  • Regional RV akinesia or dyskinesia or dyssynchronous RV contraction and one of the following:

    • RV EDV/BSA ≥100 to 110 mL/m 2 (male) or ≥90 to 100 mL/m 2 (female)

    • RV ejection fraction >40 to ≤45%

Tissue Characterization of Wall

Major

  • Residual myocytes <60% by morphometric analysis (or <50% if estimated), with fibrous replacement of the RV free wall myocardium in ≥1 sample, with or without fatty replacement of tissue on endomyocardial biopsy

Minor

  • Residual myocytes 60% to 75% by morphometric analysis (or 50% to 65% if estimated), with fibrous replacement of the RV free wall myocardium in ≥1 sample with or without fatty replacement of tissue on endomyocardial biopsy

You're Reading a Preview

Become a Clinical Tree membership for Full access and enjoy Unlimited articles

Become membership

If you are a member. Log in here

Related Posts