Prevalence of Peripheral Polyneuropathy in Patients with Cardiomyopathy Secondary to Hereditary Transthyretin Amyloidosis and V122I Mutation

This study underscores the importance of assessing patients with transthyretin amyloidosis cardiomyopathy and carriers of the V122I mutation for peripheral polyneuropathy.

In patients with a V142I mutation, more frequently known as the V122I mutation (p.V122I), systemic variant or hereditary transthyretin amyloidosis (ATTRv or hATTR) is generally believed to present with minimal peripheral polyneuropathy (PN) and a cardiomyopathy (CM) phenotype. Brewster and colleagues sought to investigate the prevalence of PN in patients presenting to a cardiology practice with a new diagnosis of ATTRv-CM p.V122I.

Between September 2019 and November 2020, electromyography and nerve conduction studies were performed on 11 consecutive patients with newly diagnosed CM secondary to ATTRv p.V122I. Baseline demographics, clinician assessment, imaging, and laboratory findings were collected. The investigators recorded the presence and degree of PN in upper and lower extremities. Evaluation of electromyography and nerve conduction studies showed that all patients had at least mild PN in the lower extremities.

Of the 11 patients, 2 were diagnosed with severe PN, 5 were diagnosed with moderate PN, and 3 were diagnosed with mild PN. One patient had moderate PN in both the upper and lower extremities. On initial assessment, only 6 patients reported symptoms of PN. Significant uptake (grade ≥2) on 99mTechnetium-pyrophosphate imaging was found in 7 patients, and the remainder had minimal cardiac involvement.

Regardless of reported symptoms, at least mild PN was identified in all patients presenting with CM secondary to ATTRv p.V122I. This underscores the importance of properly evaluating all patients with ATTRv-CM p.V122I for PN. The investigators concluded that larger studies are warranted to establish the true prevalence of this condition.

Source: Brewster A, Keck JM, Baird M, et al. Prevalence of peripheral polyneuropathy in patients with cardiomyopathy secondary to hereditary transthyretin amyloidosis and V142I mutation. Eur J Heart Fail. 2021;23(suppl S2):2-322.

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