Effect of PCI on Exercise Time Studied in Patients With Stable Angina and Single-Vessel Disease
November 2, 2017—Results from the ORBITA trial were reported at TCT 2017, the 29th annual Transcatheter Cardiovascular Therapeutics scientific symposium held October 30 to November 2 in Denver, Colorado, and were published simultaneously in The Lancet.
The prospective, multicenter, randomized, blinded, placebo-controlled ORBITA study found no significant difference in exercise time after 6 weeks in patients with stable angina who received percutaneous coronary intervention (PCI) versus a placebo treatment. Both groups were treated with medical therapy.
As summarized in the TCT announcement, 200 patients were randomized to receive either PCI or a placebo procedure between January 2014 and August 2017 at five sites in the United Kingdom. All patients were clinically eligible for PCI based on symptoms and if they had at least one angiographically significant lesion ≥ 70% in a single vessel that was clinically appropriate for PCI. Patients with multivessel disease were excluded.
The study's primary endpoint was change in exercise time on a treadmill. The trial was designed to detect an effect size difference of 30 seconds between the two study arms at 6 weeks.
After enrollment, patients entered a 6-week medical optimization phase, which included the introduction and intensive uptitration of antianginal medications. This was followed by a prerandomization assessment that included symptom burden with Canadian Cardiovascular Society Class and the Seattle Angina questionnaire, functional capacity using cardiopulmonary exercise testing, myocardial ischemic burden using dobutamine stress echocardiography, and quality-of-life (QOL) assessment using an EQ-5D-5L questionnaire.
Patients then underwent the blinded invasive procedure. The operator performing coronary angiography also performed blinded fractional flow reserve and instantaneous wave-free ratio measurements pre- and postprocedure. Patients had auditory isolation and received sedation after the physiologic measurements. They were then randomized 1:1 to PCI with drug-eluting stents or a placebo procedure.
PCI operators were blinded to all research test data using only nonresearch clinical information.
In the placebo arm, patients were kept sedated for at least 15 minutes and the coronary catheters were withdrawn with no intervention performed. After a follow-up period of 6 weeks, patients completed the same tests as they did during the prerandomization assessment.
Complete prerandomization and follow-up data for exercise time were available in 104 patients in the PCI arm and 90 patients in the placebo arm.
The investigators found that for the primary endpoint, there was no significant difference in mean exercise times at 6 weeks between the two groups (PCI minus placebo, 16.6 seconds; 95% confidence interval [CI], -8.9 to 42; P = .2). In pairwise assessments, exercise time increased from baseline in the PCI group (mean increase, 28.4 seconds; 95% CI, 11.6 to 45.1), but not in the placebo group (mean increase, 11.8 seconds; 95% CI, -7.8 to 31.3). There were no significant differences between study arms in other secondary endpoints of health-related QOL measures including anginal symptom scores or QOL, although improvements were noted in both arms. PCI was associated with a reduction in ischemia as assessed by dobutamine stress echocardiography (change in wall motion stress index, -0.08; 95% CI, -0.11 to -0.04 compared with +0.02; 95% CI, -0.03 to 0.06; P = .0011).
Rasha Al-Lamee, MD, commented in the TCT announcement, “In patients with medically treated angina and anatomically and hemodynamically severe single-vessel coronary stenosis, PCI did not increase exercise time more than placebo. Despite PCI markedly improving hemodynamic and imaging indices, there was no significant difference between PCI and placebo in exercise time increment. This first placebo-controlled trial of PCI for stable angina suggests that the common clinical observation of symptomatic improvement from PCI may well contain a placebo component.”