N-terminal pro b-type natriuretic peptide (NT Pro-BNP) > pcg/mL COHORT B ONLY: Obtained =< days prior to registration: N-terminal pro b-type natriuretic peptide (NT-ProBNP) < ng/dL Cardiac stage or with N-terminal prohormone (NT-pro)-B-type natriuretic peptide (BNP) > ng/L NT-ProBNP > nanogram per liter (ng/L) N-terminal pro b-type Natriuretic Peptide [(NT)-proBNP] > nanograms (ng)/ Liter (L) Must meet criteria for of the following AL Amyloidosis Risk Stages (as defined by N-terminal proBNP [NT-proBNP] cut-off of < pg/mL and troponin T cut-off of . ng/mL as thresholds): Stage : both NT-proBNP and troponin T under threshold Stage : either NT-proBNP or troponin T (but not both) over threshold; Stage : both NT-proBNP and troponin T over threshold (but NT-proBNP < pg/mL) NT-proBNP < pg/mL BNP or NT-proBNP within normal limits NT-proBNP ? NT-proBNP > Amyloid cardiac biomarker stage I or II disease Staging defined by NT-proBNP and troponin T cut-offs of < pg/mL and <. ng/mL, respectively, as thresholds: Stage I, both under threshold; and Stage II, either troponin or NT-proBNP (but not both) over threshold. If troponin T is not available at local institution, troponin I may be used, but threshold is <. ng/mL. NT-ProBNP > , pg/mL