Is cardiac computed tomography (CT) as reliable as catheterization in patients with suspected coronary artery disease? Under the leadership of Charité – Universitätsmedizin Berlin, researchers from 31 European clinical institutions worked together to address this question as part of the DISCHARGE trial.
The aim of the trial was to test cardiac CT as a non-invasive alternative to catheterization, the current standard diagnostic test for intermediate-risk patients. A comprehensive analysis of the study’s results, which has been published in the New England Journal of Medicine*, suggests that CT offers a similar level of diagnostic accuracy, in addition to being associated with a lower risk of complications.
Coronary artery disease is common across the globe and is one of the leading causes of death in developed countries and aging populations. The disease is associated with impaired blood flow in the coronary arteries, i.e. the arteries which supply oxygen to the heart. Chest pain, shortness of breath and fatigue with activity can all be indicators of either chronic or acute disease, both of which are associated with an increased risk of heart attack, stroke and even cardiovascular death – examples of what are referred to ‘major adverse cardiovascular events’. Symptoms of coronary artery disease are caused by deposits inside the artery walls which build up over many years.
The current standard diagnostic test for coronary artery disease is a minimally invasive procedure known as coronary angiography (or cardiac catheterization). This test shows whether or not the coronary arteries supply a sufficient amount of blood, or if blood flow is impaired by arterial narrowing. Any narrowing detected in this manner can be treated during the procedure itself, through the use of small, inflatable balloons and extremely thin mesh tubes known as stents, which are used to prop open the newly widened blood vessels.
More than 3.5 million of these procedures are carried out in European catheterization laboratories (or cath labs) every year, and numbers continue to increase. Approximately two million (significantly more than half) of these minimally invasive procedures do not involve immediate treatment in the cath lab. In these cases, the procedure is able to rule out narrowed or blocked coronary arteries.
The main question addressed by the DISCHARGE Trial Group was whether the low-risk, non-invasive coronary CT method can provide a safe alternative to catheterization in certain patients with suspected coronary artery disease.
Principal Investigator and Full Clinical Professor from UCD School of Medicine and St Vincent’s University Hospital, Prof Jonathan Dodd said: “The trial shows that cardiac CT can be used as an accurate and safe gatekeeper as an initial test for certain patients with stable chest pain. Using a cardiac CT first strategy increases the yield of subsequent positive invasive coronary angiographies that may need intervention (stents) while avoiding negative invasive coronary angiographies. Cardiac CT is also excellent at showing the patients’ overall total coronary atherosclerotic plaque burden, a very important finding when considering preventative therapy.”
In order to test the effectiveness of the diagnostic imaging techniques in patients with stable chest pain, the project followed more than 3,500 patients for a duration of four years. Using a process known as randomization, patients were assigned by chance to either computed tomography or cardiac catheterization. If their initial evaluation ruled out obstructive coronary artery disease, participants were discharged back to their referring physician for further treatment – a step which gave the trial its name: DISCHARGE. Patients who were diagnosed as having the disease were managed in accordance with European guidelines at the time of the study.
The project was entirely collaborative between Radiology and Cardiology units across Europe. At St Vincent’s University Hospital, patients were recruited from the cardiology consultant clinics and the acute chest pain unit, with the dedicated involvement of the Consultant Cardiologists as well as the advanced nurse practitioner in Cardiology, Gerald Kearns.
Prof Dodd said: “A tremendous multidisciplinary effort involving many different clinical and research expertise from across the hospital campus allowed the successful completion of the trial. A team of experienced radiographers acquired high quality cardiac CTs for the trial, under the guidance of Sonya Allen. Siobhan Quinlan, a cardiac research nurse, was pivotal in getting the trial up and running, Sarah Foley and Joanne Clarke organised patient scheduling, Siobhan O’Rourke was instrumental in following patient outcomes and Edel Meaney, a research nurse from the UCD Clinical Research Center, was critical to the trial including finalizing the data and outcomes.
The trial was led by Prof Marc Dewey, Vice Chair of the Department of Radiology of the Charité Mitte hospital in Berlin and his team, and involved a total of 31 partner institutions from across 18 European countries.
St Vincent’s University hospital and affiliate UCD School of Medicine were chosen as the Irish site for the trial, with Prof Dodd, a Consultant Radiologist and Dr Mark Hensey, a Consultant Cardiologist as co-authors on the project.
Discussing the study’s long-term results, Prof Dewey said: “The trial confirmed that a CT-based management is safe in patients with stable (non-acute) chest pain and coronary artery disease.” Evaluation of safety was based on the incidence of major cardiovascular events over a period of up to four years. Prof Dewey said: “Among the patients referred for cardiac catheterization and included in this trial, the risk of major adverse cardiovascular events was found to be similar in both the CT and catheterization groups, occurring in 2.1% and 3.0% of patients, respectively. The incidence of major procedure-related complications was found to be four-times lower in patients managed with an initial CT strategy.”
For their overall analysis, the DISCHARGE Trial Group also included criteria such as improvements in chest pain and quality of life over the course of the trial. By helping to reduce the large number of catheterization procedures being performed, this new strategy could also help relieve pressure on health care systems.
*The DISCHARGE Trial Group. ‘CT or Invasive Coronary Angiography in Stable Chest Pain.’ Published in New England Journal of Medicine 2022 [online, 4 March 2022] https://www.nejm.org/doi/full/10.1056/NEJMoa2200963
About the European DISCHARGE project
DISCHARGE is a multinational research consortium comprising 31 partners from 18 European countries. At the project’s core is a randomized, controlled trial which includes 26 clinical sites and has been running since 2015. Drawing on insights gained as part of the Charité-based CAD-Man study (published in the British Medical Journal), the project investigates whether (and which) patients with stable chest pain and a suspected diagnosis of coronary artery disease may benefit from a diagnostic imaging strategy using computed tomography (CT) as opposed to catheterization. The DISCHARGE study was part-funded by the European Union’s Seventh Framework Program (Grant No. 603266 l ClinicalTrials.gov number NCT02400229) for a duration of 6 years (2014 to 2020).