ORBITA-STAR: Similarity Score of Induced Angina Symptoms Predicts Post PCI Improvement

The closer the similarity between patient-reported and medically induced angina symptoms, the more likely these symptoms will be improved following PCI, according to ORBITA-STAR, an n-of-1 placebo-controlled study presented at EuroPCR 2024 by Christopher A. Rajkumar, MBBS, et al., and published simultaneously in JACC.

The study was conducted in 51 patients with single-vessel disease undergoing PCI for symptom relief at five sites across the UK (average age, 62.9 years; 78% men). Most patients (72.5%) had stenosis of the left anterior descending artery. Their median fractional flow reserve was 0.68 (Q1-Q3: 0.57-0.79) and the instantaneous wave-free ratio was 0.80 (Q1-Q3: 0.48-0.89).

Before undergoing PCI, patients tracked their symptoms daily for two weeks using a smartphone app and then participated in eight randomized sessions to determine the similarity between their reported symptoms and induced symptoms and determine the similarity score.

Of these eight sessions, four included 60 seconds each of low-pressure balloon occlusion across the coronary stenosis. The other four sessions consisted of 60 seconds of placebo inflation. If the patient reported an intensity score of 0 to balloon occlusion, meaning there was no perceived sensation, the following pairs of episodes were extended sequentially by 30 seconds to maximize the probability of symptom provocation. This process was continued for a maximum duration of 2.5 minutes. At the end of each session, the patient reported how similar their induced symptoms were compared to their usual symptoms.

The primary endpoint was the ability of this similarity score to predict relief after PCI, as assessed by patients through a smartphone app. The similarity score ranged from –10, where the placebo inflation replicated the symptom and the balloon occlusion did not, to +10, where the balloon occlusion exactly replicated the symptom and the placebo inflation did not. Results showed that the median similarity score was 3 (Q1-Q3: 0.875-5.25). Overall, 76% of patients had a mean similarity score >0, meaning they found that the balloon occlusion replicated their symptoms better than the placebo inflation.

Results showed that the similarity score was a significant predictor of symptom improvement. A patient with an upper quartile similarity score of 5.25 was significantly more likely to have lower angina frequency following PCI (odds ratio [OR], 8.01; 95% credible interval: 2.39-15.86) than a patient with a lower quartile similarity score of 0.875 (OR, 1.31; 95% credible interval: 0.71-1.99); Pr(difference)>99.9%.

"Symptom-based personalization of therapy for stable CAD may offer the potential to maximize the therapeutic benefits of PCI, by identifying those patients most able to benefit, and reduce the clinical risk associated with futile revascularization in those patients who will not," write the authors.

In an accompanying editorial comment, Christina Lalani, MD, and Robert W. Yeh, MD, MSc, FACC, write the results could mean, "Our inability to consistently address angina with revascularization represents a limitation not in our therapeutic capabilities, but rather our diagnostic acumen."

"The findings," they continue, "bring scientific validity to a commonly held belief by proceduralists that the provocation of symptoms during PCI is evidence of selection of the correct lesion for intervention. However, the actionability of these findings remains unclear, since patients undergoing balloon inflation are committed to a PCI pathway."

"It is critical," Lalani and Yeh conclude, "that we concurrently strive toward building evidence-based strategies to identify the link between a given patient's symptoms and their observable disease."

Read here for more of ACC’s coverage of EuroPCR 2024 and JACC journal publications presented at the conference.\

Clinical Topics: Invasive Cardiovascular Angiography and Intervention, Stable Ischemic Heart Disease, Chronic Angina

Keywords: Angina, Stable, Fractional Flow Reserve, Myocardial, Percutaneous Coronary Intervention, Coronary Stenosis, Balloon Occlusion

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