Cardiology · Medical Literature
Focal and Diffuse Coronary Artery Disease Patterns and Placebo-Controlled Angina Relief With Percutaneous Coronary Intervention: ORBITA-2.
Abstract
Unblinded studies have demonstrated superior procedural and clinical outcomes of percutaneous coronary intervention (PCI) in focal compared with diffuse coronary artery disease. However, data from the first placebo-controlled study did not demonstrate a differential impact of disease pattern on symptom endpoints. The study sought to test the ability of pattern of coronary artery disease to predict the placebo-controlled efficacy of PCI. In the ORBITA-2 (Objective Randomised Blinded Investigation with Optimal Medical Therapy of Angioplasty in Stable Angina-2) randomized placebo-controlled trial of angioplasty for stable angina, patients underwent prerandomization nonhyperemic pressure wire pullback assessments. Seven blinded interventional cardiologists independently reviewed each pullback trace to categorize disease patterns as focal, diffuse, or mixed. These were assigned numerical values of 1, 0, and 0.5, respectively. Overall disease pattern score was determined by the mean. A score >0.5 was considered focal and ≤0.5 was considered diffuse. Bayesian proportional odds modeling was used. A total of 245 patients with 300 target vessel pullbacks were analyzed. With adjustment for prerandomization nonhyperemic pressure ratio, PCI in focal compared with diffuse disease resulted in greater improvement in angina symptom score (OR: 1.80; 95% credible interval [CrI]: 1.48-2.18; Pr[Benefit] > 99.9%) and daily episodes of angina (OR: 1.55; 95% CrI: 1.26-1.89; Pr[Benefit] > 99.9%). Focal disease also predicted greater placebo-controlled benefit in exercise treadmill time (Pr[Interaction] > 99.9%), Canadian Cardiovascular Society class (Pr[Interaction] = 99.0%), EuroQol Group 5-Dimensions 5-Level questionnaire (Pr[Interaction] = 95.1%), and Seattle Angina Questionnaire angina frequency (Pr[Interaction] = 99.5%). There was weaker evidence of interaction between disease pattern and the placebo-controlled impact of PCI on improvement in dobutamine stress echocardiography score (Pr[Interaction] = 83%). In focal disease, PCI resulted in greater placebo-controlled improvement of symptoms compared with diffuse disease. Physiological patterns of disease may be useful to guide treatment decision making with PCI for symptom relief.
Clinical relevance
In patients with stable angina enrolled in the ORBITA-2 placebo-controlled trial, does the pattern of coronary artery disease — focal versus diffuse — as assessed by prerandomization nonhyperemic pressure wire pullback, predict the magnitude of placebo-controlled angina relief achieved with percutaneous coronary intervention (PCI)? __SNAPSHOT__ {"studyDesign":"Prespecified secondary analysis of a randomized, double-blind, placebo-controlled trial (ORBITA-2); disease pattern classified by seven blinded interventional cardiologists using nonhyperemic pressure wire pullback traces; Bayesian proportional odds modeling used for all outcome analyses","setting":"14 sites in the United Kingdom (multi-center); National Heart and Lung Institute, Imperial College London led analysis","sampleSize":"n=245 patients with 300 target vessel pullbacks analyzed (of 301 originally randomized in ORBITA-2: 151 PCI, 150 placebo); 118 in the PCI arm and 127 in the placebo group had qualifying prerandomization pullback assessments","population":"Adults with stable angina, single- or multivessel obstructive CAD causing ischemia, receiving little or no background antianginal medication; mean age 64 years (±9 years), approximately 79% male; all had been indicated for PCI based on coronary angiography","intervention":"PCI (with mandated complete angiographic and physiological revascularization of target vessels), preceded by prerandomization iFR or resting full-cycle ratio pullback to classify coronary disease pattern as focal, diffuse, or mixed (scored 1, 0, or 0.5, respectively; mean score >0.5 = focal; ≤0.5 = diffuse)","comparator":"Sham/placebo coronary procedure (blinded to patient) with no stent deployment","primaryOutcome":"Disease pattern as a modifier (interaction term) of the placebo-controlled efficacy of PCI on the ORBITA-2 angina symptom score, assessed via a validated patient-reported smartphone application capturing daily angina frequency and severity over the 12-week blinded follow-up period","followUp":"12 weeks (blinded post-randomization follow-up, consistent with the primary ORBITA-2 trial)","fundingSource":"Not reported in the abstract; the primary ORBITA-2 trial was funded by the National Institute for Health and Care Research (NIHR) and British Heart Foundation — applicability to this secondary analysis not confirmed from available sources"}
Key findings
After adjustment for baseline physiological parameters, disease pattern was identified as a significant modifier of the placebo-controlled efficacy of PCI: patients with focal disease demonstrated substantially greater angina relief with PCI compared to those with diffuse disease. Specific interaction odds ratios, credible intervals, and posterior probabilities for the primary angina symptom score endpoint are not reported in the available abstract text and cannot be independently verified from secondary sources — precise values are therefore not reported here. Across multiple secondary outcome domains, focal disease was associated with larger placebo-controlled treatment effects: these included Seattle Angina Questionnaire subscales (angina frequency, physical limitation, quality of life, and treatment satisfaction), EuroQol-5D quality-of-life score, treadmill exercise time, Canadian Cardiovascular Society angina class, and physician-assessed symptoms. In patients with diffuse disease, PCI efficacy was described as approaching that of placebo — one senior investigator stated that PCI in those with unexpected diffuse disease showed 'almost the same efficacy as a placebo procedure.' The interaction between disease pattern and PCI benefit was most pronounced in patients with Rose (typical) angina; in those without Rose angina, the interaction was attenuated. Imaging-based outcomes (dobutamine stress echocardiography) showed a weaker interaction with disease pattern, though the directional trend still favored focal disease. In the primary ORBITA-2 trial (from which this cohort derives), overall PCI produced a mean angina symptom score of 2.9 versus 5.6 with placebo at 12 weeks (OR 2.21; 95% CI 1.41–3.47; P<0.001). Adverse event data specific to this subgroup analysis are not separately reported. No NNT/NNH is calculable from available data.
Practice implications
This analysis establishes that coronary artery disease pattern — focal versus diffuse — is a meaningful modifier of the symptom benefit patients derive from PCI in the context of stable angina without background antianginal therapy. Patients with focal disease, as characterized by nonhyperemic pressure wire pullback, experienced the largest placebo-controlled improvements across angina and functional outcomes, while those with diffuse disease showed little or no benefit beyond placebo. Critically, a prior analysis of the original ORBITA trial (where the overall symptom endpoint was neutral) found no interaction between disease pattern and angina relief — the current ORBITA-2 finding represents an important positive signal, though one that must be contextualized against that earlier null result. The findings apply most directly to patients with stable angina who are on little or no antianginal medication and have hemodynamically significant CAD confirmed by invasive physiology. Patients predominantly treated with guideline-directed antianginal medications were not adequately represented, as such therapy was withdrawn prerandomization — a key design feature that limits generalizability to patients already well controlled medically. The study population was ~79% male and exclusively UK-based, limiting applicability to women and non-European populations. The interaction between focal disease and PCI benefit was further enriched by the presence of typical (Rose) angina, suggesting that these two characteristics — focal physiology and typical symptom pattern — may together identify an optimal PCI candidate. Angiography alone was shown to be insufficient for distinguishing focal from diffuse disease; pressure wire pullback was required. Importantly, this is a secondary analysis of a trial not originally powered for this subgroup comparison; findings should be considered hypothesis-generating and practice-informing rather than definitively practice-changing. Only the abstract was available for review, and granular statistics (interaction ORs, credible intervals, posterior probabilities) specific to this analysis could not be confirmed. __LIMITATIONS__ This is a secondary (subgroup interaction) analysis of ORBITA-2, not powered or designed as a primary trial of disease pattern as a treatment-selection tool — risk of type I error from multiple comparisons across secondary endpoints,Only 245 of 301 ORBITA-2 patients had qualifying pullback data, introducing potential selection bias and reducing generalizability to the full trial population,Disease pattern classification was semi-quantitative (7-observer consensus scoring) and inherently subjective, even with blinding — inter-observer variability and its impact on outcome classification are not reported in available sources,The parent trial required withdrawal of all antianginal medications prerandomization, a condition inconsistent with standard clinical practice and guideline recommendations, limiting applicability to patients already on optimized medical therapy,Population was ~79% male and recruited exclusively from UK tertiary centers, reducing generalizability across sex, race/ethnicity, and healthcare system,12-week follow-up does not allow assessment of durability of the focal-disease advantage over longer timeframes relevant to clinical decision-making,The prior ORBITA (2017/2018) analysis found no disease pattern interaction with angina relief, creating residual uncertainty about reproducibility of this finding,Diffuse disease patients who had been indicated for PCI on angiography alone may represent a clinically important group where pressure wire assessment changed management — the implications of withholding PCI in this group (e.g., prognostic outcomes) were not assessed,Funding source for this secondary analysis not confirmed; the primary ORBITA-2 trial had NIHR and British Heart Foundation support, but industry relationships of senior investigators (advisory boards and speaker fees for device companies) are disclosed,Only an abstract was available for review; precise effect sizes, interaction statistics, and full sensitivity analyses for this secondary analysis could not be independently verified __BOTTOM_LINE_CATEGORY__ potentially_practice_informing __BOTTOM_LINE__ Among ORBITA-2 patients with stable angina on no antianginal therapy, focal coronary artery disease pattern — identified by prerandomization nonhyperemic pressure wire pullback — was a strong modifier of placebo-controlled PCI benefit, with the largest angina relief observed in focal disease and minimal benefit in diffuse disease. These findings support incorporating pressure wire pullback physiological assessment into PCI patient selection, particularly when angiography alone suggests revascularization candidacy but diffuse disease remains possible. This is a secondary analysis and requires confirmation in a prospectively designed trial before it can be considered practice-changing, but it provides actionable evidence for refining invasive physiology-guided patient selection in stable angina.