1351892 - Left Ventricular Inferior Aneurysm: A Multimodal Approach Towards an Unexpected Diagnosis

A 59 year old female was referred due to left ventricular inferior aneurysm on an external echocardiography. She reported frequent palpitations for many years. In her early 20s there was an incident of aborted sudden cardiac death with myocarditis as the suspected diagnosis, but no records are available.

Diagnostic Techniques and Their Most Important Findings:

The ECG showed T-wave-inversions in leads V4-6 and low voltage in the limb leads. The holter ECG showed frequent premature ventricular contractions. Transthoracic echocardiography showed akinesia of the inferior left ventricular wall and a slightly reduced right ventricular function. A coronary angiography was performed under the suspicion of right coronary artery occlusion but showed smooth coronary arteries. Endomyocardial biopsy showed moderate diffuse fibrosis but no sign of inflammation. CMR showed aneurysmata of the inferior LV and the basal RV with fibro-fatty replacement, leading to a suspected diagnosis of arrhythmogenic cardiomyopathy (ACM) with biventricular involvement. A reassessment of the biopsy in this regard was negative, with the fibrosis fraction below 25% of the myocardium and an unremarkable Plakoglobin stain. Due to the highly suspicious CMR, a genetic analysis was ordered, showing a pathogenic mutation in the Desmoplakin gene. With the CMR-findings and the genetic mutation, two major criteria for ACM were fulfilled, with the T-wave-inversions and frequent PVCs two additional minor criteria. The diagnosis of ACM with biventricular involvement was herewith confirmed.

Learning Points from this Case:

ACM is caused by hereditary mutations in genes that code desmosomal proteins. Commonly ACM is known only by its right ventricular phenotype, then called arrhythmogenic right ventricular cardiomyopathy (ARVC). Better diagnostic techniques, expecially CMR, often show left ventricular involvement, so that the general term ACM is increasingly used. Additional diagnostic criteria for left ventricular involvement (Padua criteria) were proposed in 2020, including Fibrosis by CMR as a new major criterion. Due to the variable presentation of ACM, the diagnosis should be considered in regional dysfunction of both the left and the right ventricle. CMR is the gold standard for biventricular functional assessment and additionally allows non-invasive characterization of fibrofatty degeneration of the myocardium. While myocardial biopsy remains an important diagnostic tool, it suffers from sampling error in localized diseases like ACM. A normal Plakoglobin stain cannot exclude ACM, as many other desmosomal proteins can be affected. Mutations in the desmoplakin gene commonly show left ventricular involvement, as shown in our case.