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.