TNNI3 and dilated cardiomyopathy: Despite the rich diversity of cTnI proteoforms between the various heart samples, the NP-Pep was capable of faithfully retaining the endogenous cTnI proteoform distribution initially present in the donor (Fig. 2f), dilated cardiomyopathy (Fig. 2g), and postmortem (Fig. 2h) heart samples both before and after enrichment (Supplementary Fig. 18).