Left-dominant Arrhythmogenic cardiomyopathy (LDAC)
Left-dominant Arrhythmogenic cardiomyopathy (LDAC) differs from ARVC in
more ways than only predominantly involving the LV. Ventricular
arrhythmias of typical ARVC are characterized by LBBB morphology,
whereas over 75% of LDAC demonstrated RBBB morphology. Additionally,
findings of lateral and/or inferior T wave inversion found in LDAC
differ in pattern seen with ARVC which involves anterior T-wave
inversion and epsilon waves of the right precordial
leads.16 Epsilon waves are low-amplitude positive
signals following a QRS complex that arise from prolonged depolarization
in the affected part of the myocardium (as shown in our patient, Image
2). On echocardiography, 30% of LDAC patients have LV dilation and/or
impairment with preserved RV volume and function. In the classic pattern
of ARVC, isolated RV dysfunction precedes LV involvement throughout the
disease course. In addition, there is general sparing of the septum in
late stage ARVC with LV involvement.17 It is
noteworthy that our patient manifested ventricular ectopy with RBBB
pattern (a typical characteristic of left ventricular involvement),
despite developing an epsilon wave, (which is similarly seen in typical
ARVC) along with other features of left sided involvement such as a
reduction in left ventricular function and the interval development of
left ventricular fibrosis seen on CMR.