NPPB and cardiac amyloidosis: Multivariate analysis using a Cox proportional hazards regression model with backward elimination showed that female sex (HR, 2.343; 95% CI, 1.001 to 5.481; P=0.049) and BNP (HR, 1.041; 95% CI, 1.011 to 1.071; P<0.01) were predictors of mortality in both groups of cardiac amyloidosis.