ORBITA

Published

Al-Lamee R, et al. "Percutaneous coronary intervention in stable angina". Lancet. 2017. epub 2017-11-02:1-11.
PubMed • Full text • PDF

Clinical Question

In patients with stable angina despite medical therapy and single-vessel disease, does PCI improve angina as measured by treadmill exercise time compared to placebo procedure?

Bottom Line

In patients with stable angina despite medical therapy, PCI does not improve angina as measured by treadmill exercise time compared to placebo procedure, with both arms receiving anti-anginal therapy. PCI also failed to improve angina as assessed by validated questionnaires or improve overall quality of life.

Major Points

Percutaneous coronary intervention (PCI) is commonly utilized for stable angina although evidence for its use is questionable. The previous COURAGE trial randomized patients with stable angina to either PCI or medical therapy and found no difference with regard to myocardial infarction and death. There was a suggestion that patients who received PCI were more likely to be free of angina with a higher quality of life at 6 months, although this benefit disappeared by 36 months. Meta-analyses including COURAGE and other similar trials have also failed to demonstrate a clear benefit to PCI in patients with stable angina. As a result of these findings, current consensus guidelines recommend medical therapy as first-line for treatment of stable angina, but continue to support the use of PCI in patients with obstructive coronary disease who remain symptomatic despite medical therapy. Notably, these previous trials have not blinded patients to treatment allocation, raising the question of whether symptomatic improvement related to placebo effect. A large randomized, placebo-controlled trial of PCI in stable angina was needed to further elucidate these issues.

The 2017 Objective Randomised Blinded Investigation with optimal medical Therapy of Angioplasty in stable angina (ORBITA) trial randomized 200 patients with stable angina despite medical therapy to PCI or sham PCI (coronary angiography and iFR/FFR measurement but no stent placement) and assessed for a primary outcome of improvement in treadmill exercise time. At 6 weeks, there was no significant difference between groups in the improvement in treadmill exercise time. There was also no significant difference between groups in multiple subjective measures of anginal burden and quality of life. Patients randomized to PCI did have a greater improvement in peak stress wall motion score versus placebo (difference of differences -0.09) but the clinical relevance of this is questionable. Adverse event rates were low in both groups.

ORBITA provides the first placebo-controlled evidence of the efficacy of PCI on angina. The effect size was smaller than expected, and not statistically significant. Previous studies showing subjective benefit may have been driven primarily by a strong placebo effect. These findings provide further support for the option of medical management in stable angina. Notably, however, ORBITA used standard clinical approaches, namely symptomatic, routine clinical testing plus angiographic guidance for dedicing on PCI. Only 94% of patients had a positive ischemia test. Pressure-based modalities (iFR/FFR) have been used in unblinded studies (DEFER, FAME, FAME 2 and FUTURE) to guide placement of stents. FAME found benefit in pressure-based modalities than angiographically-guided PCI, while FUTURE was stopped after suggesting the opposite. Whether identifying lesions by iFR/FFR for PCI would be more effective in reducing angina in stable CAD remains unknown but is one of the planned substudies of ORBITA, and the reason it randomised patients across the FFR 0.80 boundary.

Guidelines

As of December 2017, no guidelines have been published that reflect the results of this trial.

Design

• Multicenter, double-blind (sham procedure), randomized trial
• N=200
  • Angiography-guided PCI (n=100)
  • Sham PCI (n=100)
• Setting: 5 centers in UK
• Enrollment: December 2013 - July 2017
• Duration of follow-up: 6 weeks
• Analysis: Intention-to-treat
• Primary Outcome: Difference in treadmill exercise time increment (s)

Population

Inclusion Criteria

• Aged 18-85
• Both of:
  • Angina or equivalent symptoms
  • At least one angiographically significant (≥ 70%) lesion in a single vessel that is appropriate for PCI

Exclusion Criteria

• Angiographic stenosis ≥ 50% in a non-target vessel
• Acute coronary syndrome
• Previous CABG
• Left main disease
• Contraindication to drug eluting stent
• Chronic total occlusion
• Severe valvular disease
• Severe left ventricular systolic dysfunction
• Moderate or greater pulmonary hypertension
• Life expectancy < 2 years
• Inability to provide informed consent

Baseline Characteristics

From all groups.

• Demographics: Age 66 years, male 73%
• Comorbidities: BMI 28.7, smoker 13%, HTN 69%, HLD 72%, DM 18%, previous MI 6%, previous PCI 13%
• Cardiac: Normal LV function 92%
• Angina: CCS I 3%, CCS II 59%, CCS III 39%, angina duration 12.5 months
• Angiographic: LAD culprit 69%, RCA culprit 16%, LCx culprit 10%, QCA area stenosis 84.4%, FFR 0.69, iFR 0.76
• Stent: Median length 24, median diameter 3.1mm, post-dilation 75%, FFR post-PCI 0.90, iFR post-PCI 0.95

Interventions

• Patients randomized 1:1 to PCI or sham PCI
• Patients were approached after diagnostic angiography and enrolled after giving informed consent
• Patients allocated to PCI underwent stenting of all lesions deemed angiographically significant
• In the placebo group, patients were kept sedated for at least 15 minutes on the table and the coronary catheters were withdrawn with no intervention performed
• After enrollment, the study consisted of two consecutive phases
  • Phase 1: 6-week medical optimization phase focused on initiation and uptitration of guideline-directed medical therapy
  • Baseline prerandomization assessment
  • Phase 2: 6-week post-randomization blinded period
• Medical optimization was focused on antianginal therapy, with goal of at least two antianginal medications per patient
• At enrollment, patients completed the Seattle Angina Questionnaire and 5 level version of the EuroQol 5 dimensions questionnaire
• Prerandomization assessment and 6-week follow-up assessment consisted of CCS questionnaire, Seattle Angina Questionnaire, CPET, dobutamine stress echocardiography, and EQ-5D-5L questionnaire
• All patients were pretreated with dual antiplatelet therapy and were continued until the last assessment visit
• Coronary angiography was performed via a radial or femoral arterial approach with auditory isolation achieved using headphones
• After follow-up assessment, patients were unblinded and given the opportunity to undergo PCI after consultation with their physician

Outcomes

Comparisons are PCI vs. sham PCI

Primary Outcomes

Change in treadmill exercise time (s)

28.4 (95% CI 11.6 to 45.1) vs. 11.8 (95% CI -7.8 to 31.3), difference 16.6 (95% CI -8.9 to 42.0), p=0.20

Secondary Outcomes

Change in peak oxygen uptake (mL/min)

-2.0 (95% CI -54.1 to 50.1) vs. 10.9 (95% CI -47.2 to 69.0), difference -12.9 (95% CI -90.2 to 64.3), p=0.74

Time to 1mm ST depression (s)

472.7 vs. 470.1, p=0.16

Change in SAQ - Angina frequency

14.0 (95% CI 9.0 to 18.9) vs. 9.6 (95% CI 3.6 to 15.5), difference 4.4 (95% CI -3.3 to 12.0), p=0.26

Change in EQ-5D-5L-QoL

0.03 (95% CI 0.00 to 0.06) vs. 0.03 (95% CI 0.00 to 0.07), difference 0.0 (95% CI -0.04 to 0.04), p=0.99

Change in Duke treadmill score

1.22 (95% CI 0.37 to 2.07) vs. 0.10 (95% CI -0.99 to 1.19), difference 1.12 (95% CI -0.23 to 2.47), p=0.10

≥ 1 CCS angina class improvement

27 (26%) vs. 22 (24%), p=NS

Adverse Events

• No deaths
• 3 periprocedural major bleeding events (two with PCI and one with placebo)
• In 4 patients in the placebo group, PCI was needed for a pressure-wire related complication

Criticisms

• PCI was dictated by angiographic guidance rather than physiologic guidance (i.e., using iFR or FFR), which has been shown to be more efficacious. For example, ~30% of patients underwent stenting for iFR/FFR negative lesions that were unlikely to be contributing to angina. This may have underestimated the benefit of PCI.
• Pre-randomization medical optimization phase was very intensive, involving 1-3 telephone consultations per week and regular monitoring of home BP and HR measurements to achieve optimal medical therapy. It is unlikely that this protocol can be achieved in a real-world setting.
• 6-week follow up period cannot rule out the presence of a longer-term benefit of PCI

Funding

• NIHR Imperial Biomedical Research Centre, Foundation for Circulatory Health, Imperial College Healthcare Charity, Philips Volcano, NIHR Barts Biomedical Research Centre
• The funders of the study had no role in the study design, data collection, data analysis, data interpretation, or writing of the report