The heart is a metabolically active organ with high energy demands that depend on mitochondrial oxidative phosphorylation, however as the heart begins to fail there is metabolic inflexibility and changes in mitochondrial function. Epigenetic changes such as DNA methylation can modify the transcription of genes essential for normal mitochondrial function, however this has not been studied in Stage B or pre-heart failure (HF). In 752 participants from the Project Baseline Health Study, we tested differences in DNA methylation in mitochondrial-related genes for association with Stage B HF compared to Stage A (at-risk for HF). We then validated these findings in 918 participants from the CATHGEN study for risk of incident HF hospitalization. One region on chromosome 13 overlapping with the cysteinyl-tRNA synthetase 2 (CARS2) gene, containing five cytosine-phosphate-guanine (CpG) probes, was significantly associated with a small mean regional increase in DNA methylation in Stage B HF (0.63%, Stouffer p=0.005). In CATHGEN, one CARS2 probe, cg08289839, was significantly associated with time-to-incident HF hospitalization (adjusted HR 1.74 [95% CI 1.18-2.56], FDR p=0.02). In this study of epigenetic changes of mitochondrial genes, these results indicate that CARS2 DNAm may play a role in HF pathogenesis and should be studied in future HF research.

All authors acknowledge institutional research grants from Verily Life Sciences. 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. FR reports grants from the National Institutes of Health (NIH) National Heart, Lung, and Blood Institute (R01HL168188; R01HL167974; R01HL169345), American Heart Association/Harold Amos Medical Faculty Development program, and Doris Duke Foundation (Grant #2022051); equity from Carta Healthcare and HealthPals; and consulting fees from HealthPals, Novartis, NovoNordisk, Esperion Therapeutics, Movano Health, Kento Health, Inclusive Health, Edwards, Arrowhead Pharmaceuticals, HeartFlow, iRhythm, Amgen, and Cleerly Health outside the submitted work. AH reports 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.

https://clinicaltrials.gov/ct2/show/NCT03154346

The Project Baseline Health Study and this analysis were funded by Verily Life Sciences, South San Francisco, California. J.A.R is supported by 1K38HL175026. K.K. is supported by 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:

. Informed consent was obtained from all participants enrolled in PBHS in accordance with the Helsinki declaration. The study was approved by a central Institutional Review Board (the WCG IRB; approval tracking number 20170163, work order number 1-1506365-1) and IRBs at each of the participating institutions (Stanford University, Duke University, and the California Health and Longevity Institute).

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.