Cutting-edge Imaging May Provide Insight into the Functional Significance of a Stenosis

A novel study aims to evaluate whether optical coherence tomography (OCT) parameters may predict fractional flow reserve (FFR) values and assess if OCT parameters may predict clinical outcome in patients with negative FFR. The study was presented as late-breaking science at the SCAI 2020 Scientific Sessions Virtual Conference.

OCT imaging, a cutting-edge high-resolution intracoronary imaging technique generally used to characterize plaque morphology and to guide optimization of percutaneous coronary intervention, may also provide some insights into the functional significance of a stenosis.

“The idea of predicting hemodynamic relevance of coronary lesions from imaging is extremely appealing. In this collaborative study we sought to investigate if OCT parameters may help predicting the presence of hemodynamically significant stenoses among angiographically-intermediate coronary lesions (AICL),” says Rocco Vergallo, MD, PhD. “We put together data collected from different studies so that we have been able to analyze individual data of about 500 patients.”

The research team, under the leadership of Francesco Burzotta, MD, designed a multicenter, international study using individual patient’s level data pooled analysis. Stable or unstable patients who underwent both FFR and OCT of the same coronary lesion were enrolled. Primary outcome measures were OCT parameters predicting an FFR < 0.80, including mean lumen area (MLA), percentage area stenosis (%AS), and presence of plaque thrombus/rupture. Secondary outcome was the incidence of Major Adverse Cardiac Events (MACE) in patients not undergoing revascularization based on negative FFR (?0.80). MACEs were defined as the composite of cardiac death, spontaneous myocardial infarction (MI), and target lesion revascularization.

A total of 502 coronary lesions in 489 patients were included. A significant correlation was observed between OCT-MLA and FFR values (R = 0.525, p < 0.001), and between OCT-%AS and FFR values (R = -0.482, p < 0.001), while plaque thrombus/rupture did not differ significantly. At ROC analysis, an OCT-MLA < 2.0 mm2 showed a good discriminative power to predict an FFR < 0.80 (AUC 0.80), as well as an OCT %AS >73% (AUC 0.73). When considering proximal coronary segments only, the best OCT cutoff values predicting an FFR < 0.80 were MLA < 3.1 mm2 (AUC 0.82), and %AS >61% (AUC 0.84). Among 105 patients who had not undergone revascularization based on negative FFR and had completed the clinical follow up, 11 (10.5%) had MACE. Median followup time was 6 years (IQR: 2.3-8.3). Patients with MLA <2.0 mm2 showed a nonsignificantly higher incidence of MACE than those with MLA ?2.0 mm2 (16.7% vs. 9.2%, p = 0.139).

“These findings are important because they may allow interventional cardiologists to gather both data on plaque morphology/lumen dimension and indirect information on the functional significance of a stenosis by using an imaging catheter only, without the need for an additional pressure wire,” Vergallo adds. “This would, in turn, reduce both patient risk and healthcare expenses.”