Background Asymptomatic structural heart disease, or stage B heart failure (HF), is clinically relevant for early HF diagnosis and prevention; circulating biomarkers could have prognostic significance for this. Thus, we performed proteomics discovery in a well-phenotyped cohort, the Project Baseline Health Study (PBHS).

Methods PBHS recruited participants with and without cardiovascular risk, collecting enrollment plasma biospecimens and cardiac imaging. Proteomic profiling (N=289) was performed using mass spectrometry on 503 individuals (185 stage B HF cases, 318 stage A HF controls). Logistic regression identified stage B-associated proteins, which were then eligible for inclusion in a joint protein score derived via elastic net. Scores were assessed for incident HF prediction in the UK Biobank (UKB) and the Exenatide Study of Cardiovascular Event Lowering (EXSCEL), examined for exenatide interactions in EXSCEL, and tested for imaging trait associations in PBHS and UKB. Mechanistic analyses of multivariate significant proteins included incident HF prediction in UKB and EXSCEL, Mendelian randomization (MR), and targeted methylation loci associations with stage B HF in PBHS.

Results Sixty-five proteins were associated with cases, of which 32 (49%) were retained via elastic net modeling; the resulting protein score showed good discrimination for cases versus controls (AUC 0.71, 95% CI [0.60, 0.82]). The protein score was significantly associated with incident HF in UKB and EXSCEL and left ventricular mass index (LVMI) in PBHS, as well as beneficially modified by exenatide in EXSCEL. Multivariate analysis prioritized 11 proteins associated with cases for mechanistic study, of which 4 (B2M, EFEMP1, CST3, HBB) showed significant incident HF associations in UKB and EXSCEL; CST3 and HBB were significant in MR. Methylation of cg08099136 in PSMB8 was significantly associated with cases in PBHS.

Conclusions Our findings highlight inflammatory biomarkers and mechanisms underpinning stage B HF. CpG hypomethylation at PSMB8 may be implicated in inflammation, resulting in increased LVMI (a known HF risk factor), with circulating B2M a byproduct of this process.

ClinicalTrials.gov Identifier NCT03154346

All authors acknowledge institutional research grants from Verily Life Sciences. SS and SP report employment and equity ownership in Verily Life Sciences. RM received research support and honoraria from Abbott, Alleviant Medical, American Regent, Amgen, AstraZeneca, Bayer, Boehringer Ingelheim, Boston Scientific, Cytokinetics, Fast BioMedical, Gilead, Innolife, Eli Lilly, Lexicon, Medtronic, Medable, Merck, Novartis, Novo Nordisk, Pfizer, Pharmacosmos, Relypsa, Reprieve Cardiovascular, Respicardia, Roche, Rocket Pharmaceuticals, Sanofi, Verily, Vifor, Windtree Therapeutics, and Zoll. KM reports grants from Verily, Afferent, the American Heart Association (AHA), Cardiva Medical Inc, Gilead, Luitpold, Medtronic, Merck, Eidos, Ferring, Apple Inc, Sanifit, and St. Jude; grants and personal fees from Amgen, AstraZeneca, Bayer, CSL Behring, Johnson & Johnson, Novartis, and Sanofi; and personal fees from Anthos, Applied Therapeutics, Elsevier, Inova, Intermountain Health, Medscape, Mount Sinai, Mundi Pharma, Myokardia, Novo Nordisk, Otsuka, Portola, SmartMedics, and Theravance outside the submitted work. AH reports grants from Verily; grants and personal fees from AstraZeneca, Amgen, Bayer, Merck, and Novartis; and personal fees from Boston Scientific outside the submitted work. The other authors have no conflicts of interest to disclose.

The Baseline Health Study and this analysis were funded by Verily Life Sciences, South San Francisco, California. Kalyani Kottilil is funded by a National Institutes of Health (NIH) F31 grant [1F31HL175914-01].

I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained.

Yes

The details of the IRB/oversight body that provided approval or exemption for the research described are given below:

The study was approved by the Duke University and Stanford University Institutional Review Boards. Informed consent was obtained from all participants enrolled in the Project Baseline Health Study in accordance with the Declaration of Helsinki.

I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals.

Yes

I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance).

Yes

I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable.

Yes

The deidentified PBHS data corresponding to this study are available upon request for the purpose of examining its reproducibility. Requests are subject to approval by PBHS governance.