Heart failure due to coronary artery disease represents a significant cause of mortality. The detection of patients eligible for bypass surgery is a pivotal concern. Nevertheless, the optimal approach for patient selection based on conventional imaging scans remains unclear. The proposed method (Hyperpolarized 13C MRI) has gained extensive use in evaluating in vivo metabolism. This method avoids ionizing radiation and provides critical insights into cardiac function. The feasibility study aims to investigate this method for patient selection before bypass surgery. This innovative imaging technique facilitates the identification of two simple molecules, bicarbonate and lactic acid, produced at high rates by normal heart metabolism. Both bicarbonate and lactate originate from the same precursor molecule, pyruvate. The data generated from this study holds the potential to refine diagnostic precision.

PRIMARY OBJECTIVES:

The principal aim of this investigation is to employ noninvasive techniques for the in vivo assessment of segmental myocardial metabolism. This will be achieved by measuring the hyperpolarized (HP) 13C bicarbonate-to-lactate (bic/lac) ratio in patients scheduled for coronary artery bypass surgery (CABG), both preoperatively and 4-6 months postoperatively. These findings will be compared with a control group of healthy subjects to establish normal metabolic values.

SECONDARY OBJECTIVES:

In addition to the primary objectives, this study seeks to accomplish the following secondary objectives:

1. To ascertain the safety profile and tolerability of HP [1-13C] pyruvate administration during the MRI exam.
2. To evaluate the reproducibility of the HP 13C MRI data if the optional second injection of hyperpolarized 13C pyruvate is administered.

EXPLORATORY OBJECTIVES:

In pursuit of further insights, this research also aims to explore the following:

1. Investigate potential associations between blood measurements for pyruvate, triglycerides, free fatty acids, and insulin levels with the bicarbonate/lactate ratio within the myocardium.
2. Explore correlations between segmental myocardial metabolism (the bic/lac ratio) and mechanical function, such as echocardiographic measurements of wall motion.

The eligibility criteria for this feasibility study are designed to select participants who will provide valuable insights into myocardial metabolism using HP-13C MRI in various contexts related to ischemic heart failure. These criteria aim to ensure that the study population is diverse and representative of the patient groups under investigation.

Inclusion/Exclusion Criteria:

• Age range: 20 to 80 years
• Sex: Random allocation
• Left ventricular ejection fraction (LVEF):
• Preoperative patients with LVEF < 0.35
• Healthy subjects with LVEF > 0.50
• Clinical history:
• Previous myocardial infarction (MI): Excluded for healthy subjects, included for preoperative patients.
• Diabetes mellitus: Excluded for all participants.
• Hypertension: Included for all participants
• Mean blood pressure: Systolic < 140 mm Hg and Diastolic < 90 mm Hg for all participants
• Mean heart rate: 78 beats/min for all participants
• Current smoker status: Included but will be reported.
• Medication use within 24 hours: Use will be reported.
• Coronary artery bypass surgery history: Excluded for healthy subjects, included for preoperative patients.
• Infarct type and location: Excluded for healthy subjects, included for preoperative patients with various Q-wave infarct types and locations.
• Number of diseased coronary vessels: Excluded for healthy subjects, included for preoperative patients with at least one diseased vessel.
• Additional medical history and clinical data: Variations in data availability are expected based on the practices of referring physicians and will be documented.

Potential human subjects will be identified and referred by cardiothoracic surgeons (Drs. Peltz or Jessen.) and their clinical team will discuss the opportunity to participate with their patients or potential subjects. A research nurse from the Cardiovascular and Thoracic Surgery Clinical Trials office will directly contact the subject to further discuss study participation, otherwise, the details and contact information of clinical study coordinator will be provided for prescreening. Once the study candidate expresses interest, details will be forwarded to the Advanced Imaging Research Center and an appointment will be scheduled for the 13C metabolic imaging exam. All NIH and UTSWMC regulations related to confidentiality, recruitment practices, etc., will apply. All patients will be reviewed for medical history, demographics, subject eligibility criteria, MRI screening form, informed consent, and pregnancy test for females of child-bearing potential.