New England Journal of Medicine December 21, 2023

A Placebo-Controlled Trial of Percutaneous Coronary Intervention for Stable Angina (ORBITA-2)

Christopher A. Rajkumar et al.

Bottom Line

In patients with stable angina who were not receiving antianginal medications, percutaneous coronary intervention significantly reduced angina symptom scores compared to a placebo procedure.

Key Findings

1. At 12 weeks, the mean angina symptom score was significantly lower in the PCI group compared to the placebo group (2.9 vs. 5.6; Odds Ratio [OR] 2.21, 95% CI 1.41-3.47; P<0.001).

2. The clinical benefit was primarily driven by a reduction in the number of daily angina episodes (0.3 in the PCI group vs. 0.7 in the placebo group; OR 3.44, 95% CI 2.00-5.90).

3. There was no significant difference between the groups in the daily number of antianginal medications prescribed (0.2 vs. 0.3 units; OR 1.21, 95% CI 0.70-2.10).

4. Acute coronary syndromes occurred in 4 patients in the PCI group and 6 patients in the placebo group, with only 1 patient in the placebo group requiring unblinding for unacceptable angina.

Study Design

Design

RCT

Double-Blind

Sample

301

Patients

Duration

12 weeks

Median

Setting

Multicenter, UK

Population Patients with stable angina or angina-equivalent symptoms, anatomical evidence of severe coronary disease (≥70% stenosis invasively or ≥90% via CT), and objective evidence of ischemia, who had successfully discontinued all antianginal medications.

Intervention Percutaneous coronary intervention (PCI) with drug-eluting stents aiming for complete physiological and anatomical revascularization of ischemic territories.

Comparator Placebo (sham) procedure involving diagnostic angiography and auditory isolation, but no intervention or balloon inflation.

Outcome An angina symptom score (ordinal scale from 0 to 79) calculated daily over 12 weeks, based on the number of angina episodes, antianginal medications prescribed, and clinical events (unblinding, acute coronary syndrome, or death).

Study Limitations

• The follow-up period was limited to 12 weeks, precluding the evaluation of long-term symptomatic durability and hard clinical endpoints such as mortality or myocardial infarction.

• Complete discontinuation of antianginal medications prior to randomization deviates from standard guideline-directed medical therapy (GDMT) in real-world clinical practice.

• The requirement for patients to willingly stop all antianginal medications and undergo a potential sham procedure likely introduced selection bias toward highly motivated individuals.

• The primary endpoint utilized a novel, ordinal angina symptom score (0-79), which can be complex to translate into traditional metrics of exercise capacity or standardized quality-of-life instruments.

Clinical Significance

ORBITA-2 definitively establishes that PCI provides true, physiological, non-placebo relief of stable angina in patients with ischemic coronary artery disease. By proving efficacy as a monotherapy, the trial validates PCI as a legitimate, upfront alternative to escalating medical therapy, supporting personalized, patient-centered shared decision-making for those intolerant of or nonadherent to polypharmacy.

Historical Context

The predecessor trial, ORBITA (2017), shocked the cardiology community by demonstrating no significant improvement in treadmill exercise time for PCI versus a sham procedure in stable angina patients optimized on multi-drug medical therapy. This sparked intense debate over whether PCI's symptomatic benefits were entirely due to a placebo effect. ORBITA-2 was specifically designed to isolate the physiological impact of stenting by removing the confounding overlap of background antianginal medications, serving as a fundamental proof-of-concept for the intervention.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

How does the mechanism of angina relief differ between a beta-blocker and percutaneous coronary intervention (PCI) in a patient with stable ischemic heart disease?

Key Response

PCI mechanically increases oxygen supply by reducing the coronary stenosis and thus decreasing resistance to flow. Beta-blockers primarily reduce myocardial oxygen demand by decreasing heart rate and contractility. ORBITA-2 specifically tests the mechanical supply-side intervention without the confounding effect of demand-reducing medications.

Resident

In light of the ORBITA-2 findings, how should you counsel a patient with stable angina and a single-vessel focal stenosis regarding the choice between starting an antianginal medication versus proceeding directly to PCI?

Key Response

ORBITA-2 demonstrates that PCI is an effective antianginal therapy on its own, unlike the first ORBITA trial which showed minimal added benefit on top of optimal medical therapy. Residents should use this to counsel patients that both pathways (PCI or medications) are viable first-line options for symptom relief, allowing for shared decision-making based on patient preference regarding daily pills versus an invasive procedure.

Fellow

The primary endpoint in ORBITA-2 was the angina symptom score. How does the complete cessation of antianginal medications during the trial's run-in phase impact our understanding of the placebo effect in invasive procedures compared to the original ORBITA trial?

Key Response

The original ORBITA trial showed that when patients are heavily medicated, the incremental benefit of PCI over placebo is negligible, suggesting a large placebo effect or overlapping efficacy. By removing medications, ORBITA-2 isolated the pure physiologic effect of PCI, proving it has a measurable, non-placebo benefit on symptoms. Fellows must integrate these to understand that while PCI works, its symptomatic benefit is significantly blunted when background medical therapy is already optimized.

Attending

Does ORBITA-2 justify shifting our practice paradigm from a 'medications first, PCI for refractory symptoms' approach to offering upfront PCI as an equivalent alternative to medical therapy for stable angina?

Key Response

While ORBITA-2 proves PCI works as monotherapy for symptom relief, trials like ISCHEMIA and COURAGE showed no mortality or MI benefit for upfront invasive strategies. Attendings should teach that ORBITA-2 validates PCI as a legitimate first-line option for patients intolerant to or unwilling to take antianginals, but it does not mandate PCI for all, emphasizing individualized care and symptom management over prognostic illusions.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

The ORBITA-2 trial utilized a novel smartphone-based ordinal scale (the angina symptom score) calculated daily. What are the methodological advantages and potential statistical pitfalls of using a daily patient-reported ordinal composite score over traditional treadmill exercise time as a primary endpoint?

Key Response

Daily ecological momentary assessment via smartphone reduces recall bias and captures real-world symptom burden better than a single point-in-time exercise test. However, ordinal composite scores can complicate effect size interpretation, and missing daily data requires robust imputation models. This highlights the trade-off between ecological validity and statistical complexity.

Journal Editor

How does the potential for unblinding of patients post-procedure, or the difficulty in ensuring complete antianginal washout, threaten the internal validity of a placebo-controlled procedural trial like ORBITA-2?

Key Response

As an editor, one must scrutinize the blinding integrity. Even with a sham procedure, patients might guess their allocation based on subtle procedural differences, access site bruising, or rapid symptom resolution, which could re-introduce placebo effects. Furthermore, confirming complete drug washout is critical; residual drug effects could bias the baseline run-in symptom assessments.

Guideline Committee

Current ACC/AHA guidelines emphasize optimal medical therapy before considering revascularization for stable angina. Does the sham-controlled data from ORBITA-2 warrant upgrading PCI to a first-line therapy equivalent to beta-blockers for initial symptom relief?

Key Response

The findings provide strong evidence that PCI is effective for angina relief independent of medications. A guideline committee might consider upgrading the recommendation for upfront PCI for patients who prioritize avoiding daily polypharmacy or have medication intolerances, moving away from a strict stepwise 'OMT first' mandate to a parallel 'OMT or PCI' shared decision-making model for purely symptomatic indications.

Clinical Landscape

Noteworthy Related Trials

2007

COURAGE Trial

n = 2,287 · NEJM

Tested

PCI plus optimal medical therapy

Population

Patients with stable coronary artery disease

Comparator

Optimal medical therapy alone

Endpoint

Death from any cause and nonfatal myocardial infarction

Key result: As an initial management strategy, PCI did not reduce the risk of death or myocardial infarction when added to optimal medical therapy.

2017

ORBITA Trial

n = 200 · Lancet

Tested

Percutaneous coronary intervention (PCI)

Population

Patients with severe single-vessel ischemic heart disease and stable angina

Comparator

Placebo procedure (sham)

Endpoint

Difference in exercise time increment

Key result: PCI did not increase exercise time significantly more than a placebo procedure in patients receiving optimal medical therapy.

2020

ISCHEMIA Trial

n = 5,179 · NEJM

Tested

Initial invasive strategy (angiography and revascularization) plus OMT

Population

Patients with stable ischemic heart disease and moderate or severe ischemia

Comparator

Initial conservative strategy (OMT alone)

Endpoint

Composite of cardiovascular death, myocardial infarction, or hospitalization for unstable angina, heart failure, or resuscitated cardiac arrest

Key result: An initial invasive strategy did not reduce the risk of ischemic cardiovascular events or death from any cause compared to a conservative strategy.

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