Use of biomarkers to diagnose and manage cardiac amyloidosis

Amyloidoses are characterized by the tissue accumulation of misfolded proteins into insoluble fibrils. The two most common types of systemic amyloidosis result from the deposition of immunoglobulin light chains (AL) and wild-type or variant transthyretin (ATTRwt/ATTRv). Cardiac involvement is the main determinant of outcome in both AL and ATTR, and cardiac amyloidosis (CA) is increasingly recognized as a cause of heart failure. In CA, circulating biomarkers are important diagnostic tools, allow to refine risk stratification at baseline and during follow-up, help to tailor the therapeutic strategy and monitor the response to treatment. Among amyloid precursors, free light chains are established biomarkers in AL amyloidosis, while the plasma transthyretin assay is currently being investigated as a tool for supporting the diagnosis of ATTRv amyloidosis, predicting outcome and monitor response to novel tetramer stabilizers or small interfering RNA drugs in ATTR CA. Natriuretic peptides (NPs) and troponins are consistently elevated in patients with AL and ATTR CA. Plasma NPs, troponins and free light chains hold prognostic significance in AL amyloidosis, and are evaluated for therapy decision-making and follow-up, while the value of NPs and troponins in ATTR is less well established. Biomarkers can be usefully integrated with clinical and imaging variables at all levels of the clinical algorithm of systemic amyloidosis, from screening to diagnosis and prognosis, and treatment tailoring.

Tafamidis: A Review in Transthyretin Amyloid Cardiomyopathy

Transthyretin amyloid cardiomyopathy (ATTR-CM) is a progressive, life-threatening disease characterized by the aggregation and deposition of amyloidogenic misfolded transthyretin (TTR) in the myocardium. The gradual accumulation of insoluble TTR amyloid fibrils can result in restrictive cardiomyopathy and heart failure. Tafamidis (Vyndaqel^®; Vyndamax^®), a TTR stabilizer, has been approved for use in the treatment of adults with ATTR-CM in several countries. Tafamidis stabilizes both wild-type and mutant TTR, inhibiting the formation of TTR amyloid fibrils. In the pivotal phase III ATTR-ACT trial, tafamidis significantly reduced all-cause mortality and frequency of cardiovascular-related hospitalizations relative to placebo in patients with ATTR-CM. In addition, tafamidis recipients experienced significantly less deterioration in 6-minute walk test distance and quality of life than placebo recipients over the 30-month treatment period. Treatment benefits were largely consistent between patients with wild-type TTR and patients with a variant TTR genotype. Tafamidis was generally well tolerated in patients with ATTR-CM and, with a safety profile similar to that of placebo, tafamidis is suitable for long-term use. Given that treatment for this condition has in the past been largely limited to symptom management, tafamidis constitutes a valuable disease-modifying therapy for patients with ATTR-CM.