**Introduction/Hypothesis:**
Systemic amyloidosis is caused by the multisystem extracellular deposition of insoluble, misfolded proteins. Cardiac involvement is caused in 95% of cases by deposition of immunoglobulin-derived light chains (AL amyloidosis) or transthyretin (ATTR amyloidosis), which both cause restrictive cardiomyopathy. As 70% of patients with AL amyloidosis have cardiac involvement present at diagnosis and have a median survival rate of 6 months from the diagnosis of heart failure, there is considerable interest in non-invasive imaging modalities to diagnose cardiac involvement upon initial diagnosis. Athlete’s heart is the exercise-induced cardiac phenomenon of structural and electrical remodeling of the heart to augment cardiac output required to maintain strenuous physical activity. On echocardiogram, both amyloidosis and athlete’s heart share thickening of the left ventricular walls, however, upon evaluation of strain, there is a reduction of contractility in amyloidosis and maintenance of contractility in athlete’s heart.

**Methods**
Here we present an interesting case of systemic AL amyloidosis without cardiac involvement in an athlete.

**Results**
This is a 53-year-old male athlete without prior medical history who presented with reduced exercise tolerance. Typically, the patient could perform strenuous workouts 7 days a week, however, at presentation the patient endorsed fatigue with light activity. Laboratory evaluation demonstrated a NT-proBNP of 52 pg/mL, troponin 11 ng/L, anemia, acute kidney injury, and microscopic hematuria. Electrocardiogram demonstrated a normal QRS amplitude and no heart block. Further testing was performed including serum protein electrophoresis, immunofixation electrophoresis, and a renal biopsy, which revealed IgG lambda monoclonal gammopathy and congo red staining with apple green birefringence, confirming the diagnosis of AL amyloidosis. To investigate cardiac involvement, a transthoracic echocardiogram was performed which demonstrated LVEDV of 196 ml, ventricular septum thickness of 10 mm, posterior wall thickness of 10 mm, RVEDV of 51 mm, LAVI of 42 ml/m2, GLS of -20%, and EF of 58%. These findings are not consistent with cardiac amyloidosis yet are consistent with athlete’s heart, where exercise-induced cardiac remodeling leads to ventricular chamber enlargement, wall thickening, and normal strain measurements. Moreover, these structural changes result in maintenance of systolic function and may cause augmentation in diastolic function based on training status. This patient subsequently underwent treatment with chemotherapy for his AL amyloidosis with improvement in his exercise capacity but not to his prior level.

**Conclusion**
It is difficult to say if athlete’s heart or systemic amyloidosis without cardiac involvement better explain this patient’s exercise intolerance. Reductions in peak VO2 and increased VE/VCO2 slope are noted in patients with cardiac amyloidosis and reductions in 6 minute walk times are seen in AL amyloidosis both with and without cardiac involvement, although to a greater extent with cardiac involvement. In comparison, heart failure can manifest amongst athletes due to extreme physical exertion or exacerbation of pre-existing myocardial dysfunction. Furthermore, these exacerbations may be caused by myocarditis, toxins, ischemic cardiomyopathy, dilated cardiomyopathy, hypertrophic cardiomyopathy, valvular defects, chemotherapy, or radiotherapy, and thus diagnostic workup of an athlete with exercise intolerance should be comprehensive. Although this patient was able to safely resume physical activity, there is a paucity of data and guidelines on the safety of exercise in systemic amyloidosis without cardiac involvement which warrants further research.



Athlete’s Heart in the setting of AL Amyloidosis