Plaque can lead to abnormal fractional flow reserve (FFR) — and subsequent acute coronary syndrome (ACS) — not only because of luminal narrowing, but also because of the atherosclerotic vessel wall’s impaired ability to relax and widen, a review in JAMA Cardiology suggests.
FFR had been known to identify hemodynamically-impaired lesions that are likely to produce ischemia. Less clear was how FFR predicts the subsequent risk for ACS resulting from coronary thrombosis and the rupture of lipid-rich plaques with distinct histological features.
The answer, it turns out, may be the link between necrotic cores in two-feature-positive plaque (2FPP) and the inability of the vessel to dilate. Because normal vasodilatory capacity is “a prerequisite” for preventing large pressure drops during hyperemia, a coronary stenosis with a normal FFR has a low likelihood of having plaques with high-risk features, Jagat Narula, MD, PhD, of Icahn School of Medicine at Mount Sinai in New York, and colleagues wrote in the review.
In one study, “2FPP was associated with the highest (22.5% for 27 months) event rate; events were more likely to occur in those with larger volumes, bigger necrotic cores, and a greater positive remodeling index. This more severe 2FPP, which might be associated with impaired local vasodilator capacity, would likely cause ischemia or FFR positivity.”
Narula’s group concluded that “this finding makes FFR a reliable tool to detect sizable vulnerable plaques independent of the severity of luminal narrowing. The deferral of FFR-negative lesions to optimum medical therapy is therefore safe and avoids unnecessary revascularization and stent procedures, reduces periprocedural complications, and results in fewer late stent-related events (thrombosis and restenosis) compared with a more liberal angiography-guided approach.”
“In essence, FFR may be considered a security checkpoint that prevents most plaques with vulnerable features from going undetected,” they wrote.
Narula reported no relevant relationships to disclose.
Ahmadi A, et al “Association of coronary stenosis and plaque morphology with fractional flow reserve and outcomes” JAMA Cardiol 2016; DOI: 10.1001/jamacardio.2016.0263.