Case Presentation: A 46-year-old healthy man presented with bilateral limb swelling, shortness of breath, fatigue, and orthopnea for one week. A transthoracic echocardiogram revealed a decreased ejection fraction (35-40%), severe pulmonary hypertension, diffuse hypokinesis, and significantly increased left ventricular wall thickness. Notably, he had presented with similar symptoms seven months earlier. At that time, he was found to have left ventricular concentric hypertrophy, moderately increased left ventricular wall thickness, grade 3 diastolic dysfunction, and an ejection fraction of 50-55%. On the prior admission, a coronary CT angiogram (CCTA) revealed a coronary calcium score of zero, and an outpatient cardiac catheterization showed no evidence of coronary artery disease.The patient’s current presentation, including ventricular wall thickening and low-voltage EKG, raised suspicion of infiltrative cardiac disease. Further investigations revealed elevated levels of lambda light chains and an M-spike in serum electrophoresis. Urine immunofixation demonstrated monoclonal lambda light chains. A bone marrow biopsy revealed 10-20% cellularity of plasma cells, although Congo red staining was negative. Treatment with bortezomib, cyclophosphamide, and dexamethasone was initiated for lambda-restricted monoclonal plasma cell dyscrasia. However, the patient’s condition deteriorated, and cardiogenic shock ensued. Despite the administration of vasopressors, inotropes, and other resuscitative measures, the patient had a cardiac arrest and died.
Discussion: Lambda-restricted plasma cell dyscrasia involves excess lambda light chains, leading to cardiac infiltration and life-threatening cardiac amyloidosis. This cardiac infiltration often culminates in heart failure characterized by diastolic and/or systolic dysfunction. Ischemic causes are often explored when a new diagnosis of heart failure is made. Clinicians should remain vigilant for other causes of heart failure once ischemic causes are ruled out, as in this patient. Owing to the vague nature of symptoms linked with light chain plasma cell dyscrasias, diagnosing the condition often encounters delays. Timely diagnosis is critical as a delay of more than six months from the onset of symptoms is linked to higher mortality rates. Studies report that many patients diagnosed with plasma cell dyscrasias visit multiple physicians before receiving an amyloidosis diagnosis. Due to the aggressive nature of this disease, it is paramount to maintain close patient follow-up.
Conclusions: This case underscores the uncommon and aggressive nature of lambda-restricted monoclonal plasma cell dyscrasia with cardiac involvement, resulting in rapid cardiac deterioration and death despite intensive treatment. Increasing awareness and prompt evaluation of cardiac infiltrative diseases can facilitate the early implementation of suitable therapies, potentially improving outcomes despite increasing the challenging prognosis.