Evaluation of computed tomography in patients with atypical angina or chest pain clinically referred for invasive coronary angiography: randomised controlled trial

Abstract

Objective: To evaluate whether invasive coronary angiography or computed tomography (CT) should be performed in patients clinically referred for coronary angiography with an intermediate probability of coronary artery disease.

Design: Prospective randomised single centre trial.

Setting: University hospital in Germany.

Participants: 340 patients with suspected coronary artery disease and a clinical indication for coronary angiography on the basis of atypical angina or chest pain.

Interventions: 168 patients were randomised to CT and 172 to coronary angiography. After randomisation one patient declined CT and 10 patients declined coronary angiography, leaving 167 patients (88 women) and 162 patients (78 women) for analysis. Allocation could not be blinded, but blinded independent investigators assessed outcomes.

Main outcome measure: The primary outcome measure was major procedural complications within 48 hours of the last procedure related to CT or angiography.

Results: Cardiac CT reduced the need for coronary angiography from 100% to 14% (95% confidence interval 9% to 20%, P<0.001) and was associated with a significantly greater diagnostic yield from coronary angiography: 75% (53% to 90%) v 15% (10% to 22%), P<0.001. Major procedural complications were uncommon (0.3%) and similar across groups. Minor procedural complications were less common in the CT group than in the coronary angiography group: 3.6% (1% to 8%) v 10.5% (6% to 16%), P=0.014. CT shortened the median length of stay in the angiography group from 52.9 hours (interquartile range 49.5-76.4 hours) to 30.0 hours (3.5-77.3 hours, P<0.001). Overall median exposure to radiation was similar between the CT and angiography groups: 5.0 mSv (interquartile range 4.2-8.7 mSv) v 6.4 mSv (3.4-10.7 mSv), P=0.45. After a median follow-up of 3.3 years, major adverse cardiovascular events had occurred in seven of 167 patients in the CT group (4.2%) and six of 162 (3.7%) in the coronary angiography group (adjusted hazard ratio 0.90, 95% confidence interval 0.30 to 2.69, P=0.86). 79% of patients stated that they would prefer CT for subsequent testing. The study was conducted at a University hospital in Germany and thus the performance of CT may be different in routine clinical practice. The prevalence was lower than expected, resulting in an underpowered study for the predefined primary outcome.

Conclusions: CT increased the diagnostic yield and was a safe gatekeeper for coronary angiography with no increase in long term events. The length of stay was shortened by 22.9 hours with CT, and patients preferred non-invasive testing.Trial registration ClinicalTrials.gov NCT00844220.

Conflict of interest statement

All authors have completed the ICMJE uniform disclosure form at www.icmje.org/coi-disclosure.pdf (available on request from the corresponding author) and declare that (1) MD has support from the Heisenberg programme of the German Research Foundation for the submitted work; (2) MD has relationships with Bayer, Bracco, Cardiac MR Academy, European Commission, European Regional Development Fund, German Foundation of Heart Research, German Federal Ministry of Education and Research, GE Healthcare, Guerbet, Springer, and Toshiba; BH has relationships with Bayer, Bracco, GE, Guerbet, Philips, Siemens, and Toshiba; (3) their spouses, partners, or children have no financial relationships that may be relevant to the submitted work; and (4) have no non-financial interests that may be relevant to the submitted work. Institutional master research agreements exist with Siemens Medical Solutions, Philips Medical Systems, and Toshiba Medical Systems. The terms of these arrangements are managed by the legal department of Charité–Universitätsmedizin Berlin.

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Figures

Fig 1 Flowchart of patients through the study. ECG=electrocardiography; MRI=magnetic resonance imaging; CT=computed tomography

Fig 2 Length of stay and proportion of patients discharged. Computed tomography (CT) shortened median length of stay from 52.9 hours in coronary angiography group (interquartile range 49.5-76.4) to 30.0 hours (3.5-77.3, P<0.001). Because coronary angiography in Germany is mostly done after hospital admission, patients in our study were mostly in hospital. Of the 167 patients in the CT group, 64 (38%) were managed on an outpatient basis, 11 (7%) had outpatient CT but were admitted to hospital for suspected coronary artery disease, and 92 (55%) were randomised after hospital admission for clinically indicated coronary angiography

Fig 3 Exposure to radiation in computed tomography (CT) and invasive coronary angiography group. Box plots of radiation dose in both groups are shown. Median overall radiation exposure, including invasive angiographies and revascularisations, was similar between the CT group (5.0 mSv; interquartile range 4.2-8.7) and coronary angiography group (6.4 mSv; 3.4-10.7, P=0.45). The dose for left ventriculography, which was done in 19 of the 24 patients who underwent coronary angiography in the CT group (79%) and in 141 of the 162 patients in the coronary angiography (87%), was included in the radiation exposure of the respective group

Fig 4 Need for invasive coronary angiography over time. The rate of coronary angiographies was significantly lower per patient during the first six months after randomisation to the computed tomography (CT) group (A) compared with coronary angiography group (0.25 v 1.1; B, P<0.001). In the 6-12 months after randomisation, the proportion of patients undergoing coronary angiography was the same between the groups (P=0.74)