Percutaneous coronary intervention (PCI) was performed more than 500,000 times annually worldwide for the treatment of stable angina. Evidence for its effectiveness comes from unblinded randomised trials which have shown improvements in exercise duration, angina relief and quality of life from PCI. However, these symptomatic improvements are subjective and at least some of the measured benefit might be due to the placebo effect. In all previous trials investigators and patients were aware of the treatment allocation.
The ORBITA trial was a landmark trial undertaken at 5 sites in the UK to test in a double-blind randomised design whether PCI improved exercise duration compared to placebo in patients with stable angina. Eligible patients had severe single-vessel stenosis. The design included a 6-week medical optimisation period during which anti-anginal medication was actively managed and after which a baseline exercise test was undertaken. Randomisation was in a 1:1 ratio to either PCI or placebo, which included a sham procedure whereby a coronary catheter was inserted but no stents were used to remove stenosis. The patient and investigators undertaking the assessments of outcomes were blinded to the treatment allocation. A total of 200 patients (105 PCI vs. 95 placebo) underwent randomisation. The pre-specified primary outcome measure was exercise duration and there was no difference between the groups (PCI minus placebo 16·6 s, 95% CI –8·9 to 42·0, p=0·200). This result contrasts with the results of previous unblinded trials which showed a significant improvement in exercise duration with PCI. There was also no change in secondary endpoints related to other exercise endpoints and quality of life.
The authors conclude that whilst PCI might not offer therapeutic benefit beyond medical therapy, the medical therapy in the trial was intensive so PCI offers an alternative treatment option to long-term drug therapy in stable angina.
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