Physiology-Stratified Analysis of ORBITA Presented at EuroPCR

May 23, 2018—Results from the physiology-stratified analysis of ORBITA were presented at EuroPCR 2018, held May 21–25 in Paris, France by Rasha Al-Lamee, MD, Interventional Cardiology Consultant and Principal Investigator for ORBITA. The data were also simultaneously published online ahead of print in Circulation.

Dr. Al-Lamee reported invasive physiology data from 196 patients that assessed the fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) as predictors of placebo-controlled efficacy of percutaneous coronary intervention (PCI) for stable coronary artery disease. Patients enrolled had stable angina and single-vessel coronary artery disease.

Patients underwent prerandomization research FFR and iFR assessment. Dr. Al-Lamee noted that assessment of response variables, treadmill exercise time, stress echo score, symptom frequency, and angina severity were performed at prerandomization and blinded follow-up. Effects were calculated by analysis of covariance. The ability of FFR and iFR to predict placebo-controlled changes in response variables was tested using regression modeling.

At prerandomization most patients (76.5%) had Canadian Cardiovascular Society class II or III symptoms. Mean FFR and iFR were 0.69 ± 0.16 and 0.76 ± 0.22, respectively. The majority of patients (97%) had one or more positive noninvasive or invasive tests for ischemia.

According to the investigators in Circulation, the placebo-controlled effect of PCI was more clearly seen by stress echo score and freedom from angina than the change in treadmill exercise time. The estimated effect of PCI on between-arm prerandomization-adjusted total exercise time was 20.7 seconds (95% confidence interval [CI], -4.0 to 45.5; P = .100) with no dependence on FFR (P_interaction = .318) and iFR (P_interaction = .523).

PCI improved stress echo scores more than placebo (1.07 segment units; 95% CI, 0.70–1.44; P_interaction < .00001). The placebo-controlled effect of PCI on stress echo score increased progressively with decreasing FFR (P_interaction < .00001) and decreasing iFR (P_interaction < .00001). PCI resulted in more patient-reported freedom from angina than placebo (49.5% vs 31.5%; odds ratio, 2.47; 95% CI, 1.30–4.72; P = .006) but neither FFR (P_interaction = .693) nor iFR (P_interaction = .761) modified this effect.

“From this study, we’ve seen that the degree of ischemia on iFR and FFR entirely predicts the degree of improvement in ischemia that’s seen on dobutamine stress echo,” commented Dr. Al-Lamme in a press release from EuroPCR. “What this means for physicians is that we will be able to use the iFR and FFR data before an intervention to predict exactly how much improvement in ischemia we can expect for our patients following successful stenting.”

In Circulation, investigators concluded that the blinded effect of PCI was more clearly seen by stress echocardiography score and freedom from angina than the change in treadmill exercise time. Moreover, the lower the FFR or iFR, the greater the magnitude of stress echocardiographic improvement caused by PCI.