Coronary artery bypass surgery plus medical therapy versus medical therapy alone for ischaemic heart disease: a protocol for a systematic review with meta-analysis and trial sequential analysis

Background: Despite increasing survival, cardiovascular disease remains the primary cause of death worldwide with an estimated 7.4 million annual deaths. The main symptom of ischaemic heart disease is chest pain (angina pectoris) most often caused by blockage of a coronary artery. The aim of coronary artery bypass surgery is revascularisation achieved by surgically grafting harvested arteries or veins distal to the coronary lesion restoring blood flow to the heart muscle. Older evidence suggested a clear survival benefit of coronary artery bypass graft surgery, but more recent trials yield less clear evidence. We want to assess the benefits and harms of coronary artery bypass surgery combined with different medical therapies versus medical therapy alone in patients with ischaemic heart disease. Methods: This protocol for a systematic review follows the recommendations of Cochrane and the eight-step assessment procedure suggested by Jakobsen and colleagues. We plan to include all randomised clinical trials assessing coronary artery bypass surgery combined with different medical therapies versus medical therapy alone in patients with ischaemic heart disease. We plan to search the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, LILACS, Science Citation Index Expanded on Web of Science, and BIOSIS to identify relevant trials. Any eligible trial will be assessed as high risk or low risk of bias, and our conclusions will primarily be based on trials at low risk of bias. The analyses of the extracted data will be performed using Review Manager 5, STATA 16 and trial sequential analysis. For both our primary and secondary outcomes, we will create a 'Summary of Findings' table and use GRADE to assess the certainty of the evidence. Discussion: Coronary artery bypass surgery is invasive and can cause death, which is why its use must be thoroughly studied to determine if it yields a large enough long-term benefit for the thousands of patients receiving it every year.