A Test in Context: Fractional Flow Reserve: Accuracy, Prognostic Implications, and Limitations.

Fractional flow reserve (FFR) is an invasive procedure used during coronary angiography to determine the functional significance of coronary stenoses. Its use is particularly helpful in intermediate or angiographically ambiguous lesions in the absence of noninvasive functional studies. Randomized clinical trials have reported improved clinical outcomes with the use of FFR to guide coronary revascularization, including a reduction in cardiac death or myocardial infarction, as well as costs, with an FFR-based strategy compared with a conventional angiography-based approach. Current societal guidelines provide a Class II, Level of Evidence: A recommendation to perform FFR in angiographically intermediate stenoses in the absence of stress testing or in the presence of discordant stress test results and angiographic findings. However, despite the relative ease of use of FFR, multiple technical factors can impair its accuracy, and attention to detail is critical when performing the test. This review focuses on the fundamental basics of FFR testing, clinical evidence, and limitations.