Teaching Case

A 21-year-old male patient with no relevant medical history presented with the chief complaint of palpitations during the last months. EKG showed a complete right bundle branch block and deviation of the cardiac axis. No significant alterations where documented in the echocardiogram. His aunt had died from a sudden cardiac arrest.

Slight hypokinesia at the apex of the heart and a slight thinning of the free wall of the left ventricle (LV), as well as an increase in the volume of both ventricles are seen in 4-chamber Cardiac Magnetic Resonance (CMR) cine sequence (Fig. 1). In 3-chamber CMR cine sequence, the apex of the right ventricle (RV) is dyskinetic, forming an aneurysmal sacculation with the heart movement (Fig. 2). In the late gadolinium enhancement CMR sequence, intramyocardial enhancement of subepicardial predominance is observed, affecting almost all the walls of the LV and also the RV (Fig. 3a). When calculating the ventricular volumes by the semiquantitative Simpson method, the end-systolic and end-diastolic volumes of both ventricles are elevated, with a reduced systolic function (ejection fraction).

Arrhythmogenic cardiomyopathy (AC) is a rare disease due to the replacement of myocardium by fibroadipose tissue, which predisposes to life-threatening arrhythmias, sudden death and ventricular dysfunction [1]. It is an autosomal dominant disorder with variable penetrance, and alteration of the genes that encode desmosomes (binding proteins between myocytes) [1, 2].

Traditionally this disease was called arrhythmogenic right ventricular dysplasia, since it was thought that it only affected the RV and also if significant alterations were found in the LV the diagnosis was ruled out.

However, there are different patterns of expression of this disease that not only affects the RV, but also the LV or both of them simultaneously [1, 2, 3]. In classic AC, which typically affects the RV, there is great RV dysfunction and there may be LV involvement, but minimal. In AC with left dominance, there will be an early and predominant involvement of the LV with mild RV disease. Meanwhile in biventricular cardiomyopathy both ventricles will be affected simultaneously [1, 3].

Major and minor criteria based on family history, electrocardiogram, anatomic pathology and imaging findings were proposed by the International Task Force 2010 guide. Imaging studies (echocardiography, angiography and MRI) play a complementary role in the diagnosis [4]. The criteria based on MRI are those related to changes in motility, volume and/or function of the RV. However, these criteria do not include alterations in the LV, presence of fatty infiltration, or late enhancement pattern (typically subepicardial) that is related to the presence of intramyocardial fibrosis [4, 5].

Therefore, these criteria are likely to be modified in the future in order to facilitate the diagnosis of the other AC patterns.

We must remember that AC is a rare disease that doesn’t affect exclusively the RV, as we can illustrate in this case and it is a concept to be taken into account to consider it as an alternative diagnosis.

There is no treatment available to cure this disease and the current goal of treatment is to avoid sudden death, ventricular dysfunction and reduce the burden of arrhythmias with antiarrhythmics, defibrillators or ablation therapy. Heart transplant is reserved for patients that are resistant to the therapies mentioned before [1, 2].