Functional Measurement of Coronary Stenosis
Functional Measurement of Coronary Stenosis
There are several pitfalls related to FFR measurement and a few clinical situations in which it is not reliable and should not be applied. The most important of these is acute ST-segment elevation MI. During primary PCI for acute MI, the combination of the symptoms, electrocardiogram, and angiogram makes it mostly possible to determine the culprit lesion in the majority of cases. In addition, thrombus embolization, myocardial stunning, acute ischemic microvascular dysfunction, and other factors make reaching complete microvascular vasodilation unlikely.
Therefore, FFR measurement makes no sense in the setting of acute ST-segment elevation MI. When a several days have passed (usually 5 days are considered sufficient), FFR can be applied as in routine practice. The question of whether FFR can be applied during primary PCI to assess the hemodynamic severity of remote lesions has recently been answered.
From the technical point of view, there are several pitfalls to watch when performing FFR measurement. The 2 most important pitfalls are submaximal hyperemia (underestimating the stenosis severity) and issues related to the guiding catheter. A large guiding catheter may interfere with maximum blood flow and a guiding catheter with side holes may influence proximal coronary pressure and interfere with intracoronary administration of adenosine. Such situations can be easily recognized and avoided once the operator has some experience with FFR. For a more in-depth discussion of pitfalls, we refer the reader to several excellent overviews in the literature.
Finally, there are a number of physiologic reasons why FFR can be high despite an apparently tight stenosis. This is further clarified in Table 2 .
Limitations and Pitfalls of FFR
There are several pitfalls related to FFR measurement and a few clinical situations in which it is not reliable and should not be applied. The most important of these is acute ST-segment elevation MI. During primary PCI for acute MI, the combination of the symptoms, electrocardiogram, and angiogram makes it mostly possible to determine the culprit lesion in the majority of cases. In addition, thrombus embolization, myocardial stunning, acute ischemic microvascular dysfunction, and other factors make reaching complete microvascular vasodilation unlikely.
Therefore, FFR measurement makes no sense in the setting of acute ST-segment elevation MI. When a several days have passed (usually 5 days are considered sufficient), FFR can be applied as in routine practice. The question of whether FFR can be applied during primary PCI to assess the hemodynamic severity of remote lesions has recently been answered.
From the technical point of view, there are several pitfalls to watch when performing FFR measurement. The 2 most important pitfalls are submaximal hyperemia (underestimating the stenosis severity) and issues related to the guiding catheter. A large guiding catheter may interfere with maximum blood flow and a guiding catheter with side holes may influence proximal coronary pressure and interfere with intracoronary administration of adenosine. Such situations can be easily recognized and avoided once the operator has some experience with FFR. For a more in-depth discussion of pitfalls, we refer the reader to several excellent overviews in the literature.
Finally, there are a number of physiologic reasons why FFR can be high despite an apparently tight stenosis. This is further clarified in Table 2 .
Source...