‘Cardiac ischaemia and rhythm disturbances during elective colonoscopy’ by George et al in Frontline Gastroenterology 2010;1:131–7 merits comment. The number of colonoscopies continues to rise with the introduction of the bowel cancer screening programme. Apart from the potential complications of bleeding, perforation and oversedation, the cardiovascular effects of colonoscopy have not been studied in great detail. Two controlled studies examining the cardiovascular effects of colonoscopy have reported bradycardia, hypotension and ventricular ectopics.1 2 George et al's study is the first prospective, double-blind trial that provides objective evidence of potential clinically significant ischaemic (ST-T wave) changes and rhythm disturbances during elective colonoscopy in patients with known heart disease and to a lesser extent in those patients with a known cardiovascular risk profile. The study also confirms that there …