Measures of alpha diversity across patient categories. (A) Shannon Index and (B) number of observed OTUs. Light bars: unadjusted. Dark bars: adjusted for age, sex, race/ethnicity, and antibiotic use. Multivariable adjusted p-values for any difference in Shannon Index = 0.48 and number of observed taxa = 0.66; both p-values derived from 5 df F-test. p-values for linear trend across HF Class I–IV for Shannon Index = 0.03 and number of observed taxa = 0.10. HF, heart failure; HT, heart transplantation; LVAD, left ventricular assist device; OTU, operationalized taxonomic unit.