Coronary artery disease (CAD) is the leading cause of death and disability in Singapore and worldwide. Many patients with multi-vessel CAD require surgical revascularisation by coronary artery bypass graft (CABG) surgery, and are at risk of postsurgical complications such as peri-operative myocardial injury (PMI), left ventricular dysfunction, heart failure, and death. This risk is particularly important given that the aging population, and increased prevalence of co-morbidities (diabetes, hypertension, renal failure) and complexity of cardiac surgery, mean that higher risk patients are undergoing CABG surgery. As such, new treatment strategies are required to protect the heart during CABG surgery in order to improve health outcomes in patients with CAD. In this regard, a number of animal studies have demonstrated that electroacupuncture (EA) at cardiac-related acupoints can protect the heart against the detrimental effects of acute ischaemia/reperfusion injury (IRI). However, the mechanisms underlying the beneficial effect of EA, and whether EA can protect the heart against PMI in patients undergoing CABG surgery are not known. Therefore, in this research proposal, the investigators will investigate whether EA at cardiac-related acupoints can protect the heart against PMI during CABG surgery, and the investigators will elucidate the mechanisms underlying the cardioprotective effects of EA.

There are currently no effective therapies for protecting the heart against PMI during CABG surgery and therefore, new therapeutic interventions are required to reduce the magnitude of PMI, in order to preserve LV systolic function and improve health outcomes in CAD patients undergoing CABG surgery. In this regard, electroacupuncture (EA) may provide a novel treatment strategy for protecting the heart and reducing PMI during CABG surgery, and is investigated in this TCM research proposal. The magnitude of PMI can be quantified by measuring post-operative levels of serum cardiac biomarkers such CK-MB, Troponin-T, or Troponin-I, the release of which have been associated with worse clinical outcomes following CABG surgery.

This study aims to show the benefit of EA at cardiac-related acupoints in reducing injury to the heart in terms of less PMI in patients undergoing CABG surgery and also test the possibility that EA will have benefits in other organs in terms of less acute kidney injury and preserved cognitive function, given that the blood-borne humoral factors generated by EA may also be reno- and neuroprotective. As such, the findings for this research proposal will build on evidence for the safety and efficacy of EA in the clinical setting of CABG surgery for the benefit of patients with CAD. The expected clinical benefits of reducing PMI will include improvement in short term clinical outcomes in terms of preserving LV systolic function, preventing the onset of heart failure, and improving quality of life in patients undergoing CABG surgery. This study also intends to identify and assess the cardioprotective humoral factors generated by EA at cardiac-related acupoints in stable CAD and CABG patients, providing novel therapeutic strategies for cardioprotection. In this regard, the findings from this research proposal will add new knowledge in the field of EA cardioprotection.

60 stable CAD patients undergoing planned CABG surgery will be randomized to receive either EA at cardiac-related acupoints (N=30) or standard care (N=30). A single application of EA at cardiac-related acupoints will be administered for 30 min prior to surgery. For 10 recruited CABG patients administered EA, blood samples will be collected prior to and immediately following EA, and subjected to plasma proteomics analysis to identify the factor(s) which mediate EA cardioprotection. PMI will be measured as the 48-hour area under-the-curve serum high-sensitive Troponin-T. Blood samples will be taken at pre-op and 6, 12, 24, 48 hours (post-coming off cardiac bypass) for this evaluation.

Inclusion Criteria:

• Patients with stable CAD undergoing planned CABG surgery on cardiopulmonary bypass using blood cardioplegia.
• Patients aged 21 years and above.

Exclusion Criteria:

• Patients with recent myocardial infarction (<30 days)
• Patients with significant hepatic dysfunction (If available, INR>2)
• Patients with significant pulmonary disease (If available, FEV1<40% predicted). - Patients with known renal failure with a GFR≤30 mL/min/1.73 m2.
• Patients recruited into another study which may impact on this study.

After obtaining consent, patient's study arm will be revealed via sequentially numbered, opaque, sealed and stapled envelopes.