Dilated Cardiomyopathy: Unmasking Contributing Etiologies

ABSTRACT

Background: The role of genetic conditions in the development of cardiomyopathy is well established;however, recognition and referral for genetic testing remains underutilized. Systematic review of complex cases can increase general awareness in this area of practice. Here we describe the case of a patient with resolved severe stress induced cardiomyopathy (SIC), who was ultimately found to have heterozygous transthyretin-mediated amyloidosis (TTRA). Case A 27-year-old man (family history positive for a brother status post heart transplant) presented with ataxia and cough due to legionella pneumonia. TTE showed left ventricular (LV) diastolic diameter of 6.2cm, LV ejection fraction 20-25%. He suffered rapid decompensation with mixed cardiogenic/septic shock requiring peripheral VA ECMO and Impella-CP placement. Course notable for brief cardiac arrest on hospital day (HD) 2, incidental diagnosis of COVID 19 on HD 14, conversion to VV ECMO on HD 15, and ECMO decannulation on HD 23. Repeat TTE prior to discharge showed normalization of biventricular function. Discussion(s) Despite resolution of refractory shock and normalization of biventricular function prior to discharge, the TTE finding of mild LV dilation and strong family history prompted outpatient pursuit of genetic testing which revealed a heterozygous TTRA mutation (val142ile). Work-up to assess cardiac involvement included a 99m-technetium pyrophosphate scintigraphy found to be indeterminate, an aborted endomyocardial biopsy due to inability to smoothly advance a bioptome (presumably related to ECMO cannulation), and a cardiac MRI (pending at the time of this submission). If a cardiac phenotype is discovered, the patient will be started on targeted treatment of cardiac amyloid. Screening of first-degree family members has been initiated. Conclusion(s) Given the current state of under-diagnosis of genetic cardiomyopathies and its association with significant morbidity and mortality, it is prudent to consider genetic testing in young patients based on clinical history. Examples of clinical scenarios to prompt further testing include anatomical findings (i.e. cardiac chamber enlargement, left ventricular hypertrophy), family history of cardiomyopathy, or clinical markers suggestive of alternative diagnoses (i.e. neuropathy, renal insufficiency, mediastinal lymphadenopathy). This thoughtful and algorithmic use of genetic testing may help improve long-term patient outcomes given improvements in both detection, family screening, and treatment for disease-specific cardiomyopathies.Copyright © 2022