Non-cardiac chest pain accounts for 2-5% of all emergency presentations. In the United States, it has been estimated approximately that US$8 billion was spent annually for the initial care of patients suspected to have an acute coronary syndrome, but who were subsequently found not to have coronary artery disease (1). The most common cause of non-cardiac chest pain is gastro-oesophageal reflux disease (2). Two randomized, double-blind, placebo-controlled trials on the use of omeprazole versus placebo for the treatment of NCCP have been published in the western population and reported an efficacy of 62% to 80% (3,4). High-dose omeprazole was used in the previous trials (3,4). Recently, it has been shown that rabeprazole, which is a newly developed benzimidazole proton pump inhibitor, is a more potent and rapid inhibitor of H+,K+-ATPase and acid secretion than omeprazole, lansoprazole and pantoprazole (5,6). Whether the above findings applied to Chinese population is unknown. Thus we would like to propose a randomized double-blind placebo-controlled trial to study the effects of high-dose proton pump inhibitor for the treatment of non-cardiac chest pain in Chinese population. The aim of this study is to evaluate the efficacy of high-dose proton pump inhibitor for the treatment of gastro-oesophageal reflux related non-cardiac chest pain.

Inclusion Criteria:

• Ambulatory patients with age over 18 years old
• Patients with chest pain for at least 12 weeks, in the preceding 12 months who are evaluated by cardiac catheterization or exercise radionuclide scan / persantin radionuclide scan will be assessed for suitability to enter the study. Patients will be included if the results of the cardiac investigation are normal.

Exclusion Criteria:

• Patients with history of significant cardiac, renal, pulmonary or hepatic diseases.
• Patients with history of gastrointestinal surgery or peptic ulcer diseases.
• Intake of H2 receptor blockers, bismuth or proton pump inhibitors or drugs affecting gastrointestinal motility in the preceding four weeks.
• Patients who are pregnant or lactating.
• Patients who are suffering from costochrondritis.
• Patients who are known to be sensitive to proton pump inhibitor.
• Patients with glaucoma and benign prostatic hypertrophy.