Epitranscriptomic Biomarkers for Ischemic Heart Disease (IHD-EPITRAN) - A Prospective Cohort Study
Despite advancements in medical care, ischemic heart disease (IHD) remains the leading global cause of death. IHD develops through lipid accumulation into the coronary arteries with subsequent formation of larger atherogenic plaques. During myocardial infarction (MI), a plaque ruptures and subsequent occlusion leads to a death of the heart muscle. The tissue is rapidly replaced with a scar, which may later lead to heart failure (HF). Optimally, disease biomarkers are analyzed from blood, provide insight into the disease progression and aid the evaluation of therapy efficacy. Unfortunately, no optimal biomarkers have been identified for IHD. The vast but uncounted number of patients with undiagnosed IHD, benefitting from an early diagnosis, underscore the dire need for an IHD biomarker. Epitranscriptomics, the study of posttranscriptional modifications on RNA, has recently been properly re-established. This expanding field is uncovering a new layer of regulation, controlling processes ranging from cell division to cell death. Over 170 modifications have been identified as posttranscriptional marks in RNA species. These modifications influence RNA metabolism, including export, stability, and translation. One the most common and intensively studied RNA modification is the N6-methyladenosine (m6A), the abundance and effects of which are determined by the interplay between its writers, readers and erasers. Recent findings suggest a local dysregulation of the m6A dynamics in the myocardium, coalescing in signalling pathway and contractility related RNA transcripts during hypertrophy, MI and HF. While these early reports have focused on the myocardium, the role of the m6A in the circulation during IHD remains unexplored. We hypothesize the IHD pathophysiology to be reflected in the epitranscriptome of the circulating RNA. The objective of the IHD-EPITRAN is to identify new IHD biomarkers via cohort comparison of the blood epitranscriptomes from patients with: (1) MI related with coronary angioplasty, (2) IHD treated with elective coronary artery bypass grafting, (3) aortic valve stenosis treated with valve replacement and (4) IHD-healthy controls verified with computerized tomography imaging. The RNA fractionation is followed by the quantitative modifications analysis with mass spectrometry. Ultimately, nanopore RNA sequencing with simultaneous m6A identification in their native sequences is carried out using recently published artificial intelligence-based algorithm.
• Cohort I, STEMI + PCI:
‣ Earlier PCIs and silent infarctions eligible.
⁃ ECG confirmed STEMI with Troponin I elevation and pressing chest pain.
⁃ ECG-indicated local damage correlates with recorded dyskinesia in TTE.
⁃ During acute PCI and angiography, only one clear occlusion.
⁃ Successful initial coronary artery reperfusion during PCI.
• Cohort II, Chronic IHD + elective CABG:
‣ Chronic and either CCS or NYHA II-IV symptoms for at least one month.
⁃ First and elective operation. Only heart operation to be performed.
⁃ In transthoracic echocardiogram (TTE):
• No indication of cardiomyopathy other than ischemic.
∙ No pathological remodelling (valves, ventricles and atrias).
∙ No clear indication of significant heart failure (i.e. LVEF \> 25%)
• Cohort III, elective aortic replacement therapy (AVR) for stenosis:
‣ Chronic and either CCS or NYHA II-IV symptoms for at least one month.
⁃ Operated as an open heart surgery (either prosthetic or biovalves)
⁃ No signs of IHD in coronary angiography.
⁃ Both bicuspid and tricuspid valves eligible.
• Cohort IV, IHD-negative healthy controls defined by coronary CT:
‣ Computerized tomography angiogram results are categorized as negative for coronary artery disease.
⁃ No known heart disease.