Cardiomyocyte samples were added at varying proportions to a background mixture consisting of five cell types commonly found in circulating cell-free DNA: B cells, T cells, NK cells, granulocytes, monocytes, and hepatocytes. The relative immune cell type proportions were held constant while cardiomyocte reads were spiked in at the following percentages: 0.03% (left), 0.1% (middle) and 0.3% (right), using a total genome coverage of 5. For each model, 31-cell type deconvolution was performed to determine the target cardiomyocyte fraction in 50 replicates of the true mixtures (blue bars), vs. 50 replicates of a null mixture containing no cardiomyocyte reads (red bars). A one-tailed t -test was used in ( A ) to compare the real mixture against the null mixture: *<0.05, **<0.01, ***<0.001, ****<0.00001
