Systemic Amyloidosis
A condition where abnormal folded proteins build up in organs like the heart and kidneys, slowly causing them to fail.
Emergency Management: Cardiogenic shock or fatal arrhythmias.
A rare, multi-system disease caused by the extracellular deposition of insoluble abnormal protein fibrils (amyloid) in various organs, leading to progressive organ dysfunction and failure.
Detailed Overview
Proteins become misfolded and aggregate into stable beta-pleated sheets. In AL (light chain) amyloidosis, a plasma cell clone produces misfolded light chains. In ATTR (transthyretin) amyloidosis, the liver produces normal or mutated transthyretin that misfolds. The deposits disrupt tissue architecture in the heart, kidneys, nerves, and GI tract.
Epidemiology & Demographics
AL is the most common (approx. 10 cases/million/year), typically affecting older adults (median age 65). ATTR includes a hereditary form and a wild-type form (mostly elderly men with heart failure).
Etiological Mechanism
AL: Clonal plasma cell dyscrasia. ATTR: Transthyretin protein instability (wild-type or genetic mutation like V122I).
Primary Causes
Overproduction and misfolding of specific proteins.
Precursor proteins (e.g., kappa/lambda light chains, transthyretin) undergo conformational changes due to high concentration, mutation, or aging. They form beta-pleated sheet fibrils. These fibrils deposit extracellularly, causing direct cytotoxicity and structural disruption (e.g., stiffening the heart muscle causing restrictive cardiomyopathy, or damaging glomerular basement membranes causing nephrotic syndrome).
Diagnostic Criteria & Guidelines
Requires tissue biopsy (abdominal fat pad, bone marrow, or affected organ) showing Congo red positivity with apple-green birefringence under polarized light. Typing of the amyloid via mass spectrometry is mandatory to distinguish AL from ATTR.
AL Amyloidosis: Target the plasma cells. CyBorD regimen (Cyclophosphamide, Bortezomib, Dexamethasone) + Daratumumab (anti-CD38 monoclonal antibody). ATTR Amyloidosis: Tafamidis 61 mg daily (TTR stabilizer) for cardiomyopathy.
Second-Line & Adjunctive Therapy
AL: Autologous Stem Cell Transplant (ASCT) for highly selected, fit patients. ATTR: TTR silencers like Patisiran (IV every 3 weeks) or Inotersen (SQ weekly) for polyneuropathy.
Surgical & Procedural Management
Heart or kidney transplantation in highly selected patients without extensive systemic disease.
Patient Counseling & Advice
Discuss the importance of strict adherence to heart failure regimens. For hereditary ATTR, offer genetic testing for family members.
Follow-Up & Monitoring Schedule
Frequent monitoring of cardiac biomarkers (BNP/Troponin), serum free light chains (AL), and organ function tests every 1-3 months during active therapy.
Preventive Strategies
None currently available. Early detection in patients with MGUS is key.
AL: Median survival was historically 1-2 years, but has improved to >5 years with Daratumumab/Bortezomib. Cardiac involvement dictates survival. ATTR: Median survival 3-5 years from diagnosis of heart failure, improved significantly with Tafamidis.