The use of fractional-flow reserve (FFR) resulted in significantly lower PCIs compared with intravascular ultrasound (IVUS) in patients with intermediate coronary artery disease (CAD), based on study results in this month's Journal of the American College of Cardiology: Cardiovascular Interventions.
“Because of the limitations of coronary angiography, adjunctive techniques to more accurately evaluate lesion severity are important in patients with intermediate coronary stenosis before PCI,” the authors wrote. And while FFR technology is the “reference standard” for the assessment of coronary artery stenosis, IVUS-guided PCI strategies have less mounting research, but have been reported as being safe and effective in previous studies.
To compare the clinical outcomes of these two strategies to treat coronary lesions, Chang-Wook Nam, MD, PhD, of the Keimyung University Dongsan Medical Center in Daegu, South Korea, and colleagues evaluated 167 patients with 177 de novo intermediate coronary lesions who underwent either IVUS or FFR assessment between August 2006 and June 2008.
The intermediate coronary lesions were defined by researchers as 40 percent to 70 percent diameter stenosis by visual assessment.
Patients were excluded from the study if they had previously underwent PCI for acute coronary syndrome; had previous CABG; had multiple lesions in the same epicardial artery; had left main disease, primary myocardial disease or a life threatening injury; or had contraindications to adenosine, aspirin or clopidogrel (Plavix, Bristol-Myers Squibb).
During the study, FFR was defined as the ratio between average distal coronary pressure—measured by a sensor tipped PCI guidewire—and average aortic pressure. IVUS was performed with 6F or 7F guiding catheters and the lesion sites selected were measured following American College of Cardiology guidelines.
Nam et al used major adverse cardiovascular event (MACE) rates and TVR at 12 months as the primary endpoint of the study.
Of the 177 total lesions found in the 167 patients, 83 were assessed by FFR and 94 were assessed by IVUS. The researchers reported that intracoronary adenosine was used in 79 lesions to induce maximal hyperemia.
The researchers reported that patients assessed with FFR had a higher incidence rate of multivessel disease compared to those assessed with IVUS, 66.3 percent versus 48.9 percent, respectively. The left anterior descending coronary artery was the most common location for target lesions in both study arms, 48.2 percent in the FFR arm and 58.8 percent in the IVUS arm.
While both groups had similar percentages of diameter stenosis, reference vessel diameter was larger in the IVUS-guided group.
Additionally, the rates of PCI were lower in the FFR arm compared to the IVUS arm, 33.7 percent versus 91.5 percent, respectively. When researchers evaluated for just lesions in the left anterior descending coronary artery alone, these rates continued to be lower in the FFR arm compared to the IVUS arm, 52.5 percent versus 90.9 percent, respectively.
Results showed no significant differences in MACE rates. These rates for the FFR arm were 3.6 percent and 3.2 percent in the IVUS arm. The need for TVR at 12 months was 3.6 percent for the FFR group and 2.1 percent for the IVUS group.
One non-cardiac death was reported in the IVUS group and no cases of MI or stent thrombosis were reported in either group.
While the researchers found that use of either IVUS- or FFR-guided PCI in patients who present with intermediate coronary lesions showed favorable outcomes, FFR patients had significantly lower rates of PCI.
“Assessment of a coronary lesion with intermediate severity remains challenging for interventional cardiologists,” the authors wrote. And while some researchers say PCI with DES could help in the treatment of these lesions, “recent studies have shown that stenting intermediate stenoses, without demonstrating their physiologic significance, does not improve outcome.”
The researchers said that limitations of the study stemmed from the fact that the decision to utilize FFR or IVUS was left up to operators and held the potential for selection bias.
“Both FFR- and IVUS-guided PCI for intermediate CAD were associated with favorable outcomes ... this study confirms the safety of deferring PCI in nonischemia-producing lesions,” the authors concluded. Additionally, "The rates of performed PCI in intermediate coronary lesions was significantly lower in the FFR-guided compared