A Literature Review by BCIS R&D Group
In patients with stable angina, PCI has been associated with a reduction in the relief of angina but no placebo-controlled trials have been undertaken in this patient population. The ORBITA trial was a multicentre, randomised study of 230 patients designed to assess the effects of PCI versus placebo on exercise time. Key inclusion criteria were patients aged 18-85 years with angina, at least one angiographically significant lesion (≥70% on visual assessment). After enrolment, the study consisted of two consecutive phases: first 6-weeks consisting of optimizing anti-anginal therapy and the second 6 weeks during which patients underwent follow-up assessment including Canadian Cardiovascular Society angina severity, cardiopulmonary exercise testing, dobutamine stress echocardiography, blood pressure and heart rate monitoring. At enrolment, patients completed SAW and EQ-5D-5L questionnaire. In all patients, a research invasive FFR and iFR was also undertaken in the PCI group. Of note, the values of the FFR and iFR were not available to the operator making the PCI arm an angiography guided procedure & were negative in some cases.
The primary end point of the study was the difference in exercise time increment between the groups. Secondary end points included peak VO2, change in exercise time to 1 mm ST segment depression, angina severity, physical limitation, angina stability and angina frequency. ORBITA demonstrated no significant difference in exercise time increment between the two groups (PCI minus placebo=16.6 seconds; 95% CI:-8.9-42; p=0.2). Similarly, there were no differences between the PCI arm and the placebo arm in any components of the secondary end point. Interestingly, the exercise time did increase significantly in the PCI arm and not in the medical arm, but this was not the prespecified endpoint.
The conclusion was that “in patients with medically treated angina and severe coronary stenosis, PCI did not increase exercise time by more than the effect of a placebo procedure”.
The debate rages about the trial design but employing a sham arm makes this a powerful study.