Do troponin and B-natriuretic peptide detect cardiomyopathy in transthyretin amyloidosis?

OBJECTIVES: Cardiomyopathy is a well known complication in familial amyloidotic polyneuropathy (FAP). Troponin T and B-natriuretic peptide (BNP) have been shown to be excellent markers for heart complications in AL-amyloidosis. The aim of the study was to investigate troponin T, troponin I and BNP as markers for myocardial damage and failure in FAP.

DESIGN: Retrospective investigation of patients with FAP.

SETTING: Tertiary referral centre.

SUBJECTS: Twenty-nine patients who had been submitted for evaluation of FAP.

INTERVENTIONS: Two-dimensional M-mode and Doppler echocardiography and strain echocardiographic examination. Measurement of Troponin T, troponin I and BNP.

RESULTS: Troponin T was detectable in only three patients who all had abnormal interventricular septal (IVS) thickness. Troponin I was abnormal in six patients (21%), of which only two had an increased IVS thickness. The heart function was generally well preserved in the patients in spite of hypertrophy of the IVS in 14 patients. BNP was elevated in 22 patients (76%), and it correlated significantly with IVS thickness and basal septal strain.

CONCLUSIONS: Transthyretin amyloid seems to be less harmful to myocytes than that of AL amyloid as evaluated by serum troponin T and I as well as by echocardiography. BNP appears to be a sensitive marker for cardiomyopathy in FAP, and could prove valuable for follow-up purposes as has been shown for AL-amyloidosis patients.