Prognostic value of plasma big endothelin-1 in patients with light chain cardiac amyloidosis.

Background: Light chain cardiac amyloidosis (AL-CA) is associated with a high incidence of mortality. Big endothelin-1 (ET-1), the precursor of endothelial-vasoconstrictive ET-1, is closely related to the concentration of bioactive ET-1. Association between big ET-1 and prognosis of AL-CA has not yet been documented. The purpose of this study was to evaluate the prognostic value of big ET-1 for poor outcomes in moderate to severe AL-CA.

Methods: Big ET-1 levels were determined on admission in patients with newly diagnosed AL-CA with modified Mayo 2004 stage II or III. Primary outcome was all-cause mortality. The secondary outcomes included death from cardiac cause and the composite of the primary outcome or hospitalisations due to worsening heart failure.

Results: Overall, 141 patients were retrospectively included (57 stage II, 34 stage IIIa, 50 stage IIIb). During a median follow-up time of 25.7 months, 84 (59.6%) patients died. Patients with big ET-1 levels of ≤0.88 pmol/L had longer survival than those with >0.88 pmol/L (median survival time: 34.1 months vs 15.3 months, log-rank p<0.001), which was also observed in the validation cohort (log-rank p=0.026). Higher big ET-1 levels were predictive for all-cause mortality after multivariable adjustment (HR 1.91, 95% CI 1.05 to 3.49, p=0.035). Big ET-1 levels added an incremental prognostic value over modified Mayo 2004 stage (C-index: from 0.671 to 0.696, p=0.025; integrated discrimination improvement 0.168, p=0.047).

Conclusions: Big ET-1 is a strong and independent predictor of mortality in patients with moderate to severe AL-CA, which may indicate a possible role for risk stratification in patients with this disease.