FFR GUIDED CORONARY INTERVENTION

DR. MAHENDRACARDIOLOGY,JIPMER

Challenges in daily practice• Patients with recent myocardial infarction , questions pertain to lesions

not responsible for symptoms or infarct—so called “non culprit” lesions .

• Subsequent cardiovascular events appear equally likely in non culprit lesions following MI .

• Patients with stable angina, questions surround the choice between medical therapy and revascularization

• Difficulty is identifying specific lesions that are functionally significant or that will likely lead to adverse events.

• Frequent occurrence of multivessel disease poses additional challenges. • Noninvasive tests may lack sensitivity and specificity to detect

multivessel disease and treatment decisions can be complex .

Fractional flow reserve • FFR is used to assess the physiologic consequences of

obstruction with a goal of predicting benefit from revascularization or which lesions should be treated .

• Derived from the ratio of the mean distal coronary artery pressure (Pd) to the mean aortic pressure (Pa) during the period of maximum hyperemia.

• Fractional flow reserve is not affected by changes in the hemodynamic conditions or microcirculation.

• ‘‘normal’’ ratio is expected to be 1. • Values less than 0.75 to 0.80 are considered functionally

ischemic, while those 0.94 to 1.0 normal.

What Fractional Flow Reserve Value Defines Ischemia?

FFR value <0.75 was associated with reversible ischemia on noninvasive stress testing (exercise stress test, nuclear scan, and dobutamine stress echocardiogram) with 88%sensitivity, 100% specificity, 100% positive predictive value, 88% negative predictive value, and 93% accuracy.

DEFER study and other studies have used an FFR value of <0.75 as the cutoff for ischemia.

FFR value >0.80 has been shown to exclude an ischemia-producing lesions, with predictive value of >95%.

• Coronary stenosis can be arbitrarily classified into 3 groups on the basis of FFR values:

a. non–ischemic stenosis with FFR >0.80 b. ischemia-producing stenosis with FFR <0.75.c. gray zone with FFR values between 0.75 and 0.80.

Applications for Fractional Flow Reserve in Coronary Artery Disease

• Single-Vessel Disease-• DEFER study has shown that patients with single vessel stenosis and FFR

>0.75 who did not undergo PCI had excellent outcomes. • The risk of cardiac death or myocardial infarction (MI) related to the

stenosis was <1% per year and was not reduced with PCI. • patients with single-vessel stenosis and FFR <0.75 are 5× more likely to

experience cardiac death or MI within 5 years, despite undergoing revascularization.

• medical treatment of patients with proximal left anterior descending stenosis and FFR >0.80had excellent5-year outcomes

• patients with small coronary arteries (diameter <2.8 mm), FFR can safely determine stenosis that necessitate revascularization.

• In the Physiologic and Anatomical Evaluation Prior to and After Stent Implantation in Small Coronary Vessels (PHANTOM) trial, 60 patients with small coronary arteries underwent FFR.

• group with FFR <0.75 underwent revascularization. • At 1 year, there was no occurrence of MI or death in either group.• patients with FFR <0.75, 24% underwent a repeat PCI, but only

2.6% of patients with FFR >0.75 underwent revascularization.

Left Main Stenosis

• Nonischemic FFR values (>0.80) in left main lesions are associated with excellent long-term outcomes.

• accurate LM FFR reflects flow through both the LAD and the CFX. • myocardial bed for the LM is the summed territories of both the LAD and

the CFX.• LM bed can be even larger if the RCA is occluded and there is collateral

supply from the left coronary system.• isolated LM narrowing with no LAD, CFX, or RCA stenosis reflects the

physiologic significance of just the LM narrowing.• LM narrowing plus LAD stenosis could produce a higher LM FFR because

the LM bed is reduced in size.• LM FFR alone cannot be accurately measured just as when there are serial

lesions.

• Tandem Lesions- • Tandem lesions are defined as 2 separate lesions with >50%stenosis each

in the same coronary artery, separated by an angiographically normal segment.

• If the FFR is<0.75 PCI for the stenosis that showed marked narrowing first and then repeating the FFR measurement.

• If the FFR remains<0.75,the other stenosis was revascularized as well ,in contrast, if the FFR value of the first lesion increased after PCI to >0.75, then these second lesion was treated only medically.

Multi vessel Coronary Artery Disease

Exclusion criteria• angiographically significant left main coronary artery

disease• previous coronary artery bypass surgery• cardiogenic shock• extremely tortuous or calcified coronary arteries• a life expectancy of 2 years• pregnancy • contraindication to DES placement.

• Discussion• Multi vessel CAD, favorable of FFR during PCI as compared to PCI

guided by angiography alone is maintained at 2-year follow up.• combined rate of death and myocardial infarction were significantly

lower among patients in the FFR-guided group.• composite end point of death, need for revascularization was no

longer significantly lower in FFR-guided group.• outcome in initially deferred lesions on the basis of FFR 0.80 was

excellent, underscoring the safety of the FFR guided approach. • incidence of all types of adverse events was consistently reduced by

roughly 30%.• The absolute risk for MACE was reduced by 4.5%.

Natural Course of Lesions Deferred on PCI-Based FFR Measurements

• Randomized trial to address this concern is the DEFER (FFR to Determine Appropriateness of Angioplasty in Moderate Coronary Stenosis) study was done

• 5-year event-free survival rates similar in the deferred and PCI groups .

• Composite rates of cardiac death and acute myocardial infarction in the deferred, PCI, and reference groups were 3.3%, 7.9%, and 15.7%, respectively.

• Functionally nonsignificant coronary stenosis, regardless of angiographic stenosis, could be safely deferred for up to 5 years.

IVUS VS FFR

• IVUS cannot directly estimate the functional significance of coronary stenosis.

• Strong correlations have been observed between IVUS-measured minimal lumen area (MLA) and inducible ischemia as determined by myocardial SPECT imaging, coronary flow reserve, and FFR.

• An IVUS MLA of 4 mm2 is theoretically large enough to affect coronary blood flow.

• It is generally accepted that 50% diameter stenosis, which corresponds to 75% area stenosis, is significant.

• FFR values of lesions with MLA 4 mm2 were widely scattered• 66% of analyzed lesions had MLA 4 mm2 but FFR 0.80. • Using our new, stricter criteria of MLA, 2.4 mm2, 30% of

analyzed lesions had MLA 2.4 mm2 but FFR 0.80. • use of our new IVUS MLA criteria may avoid unnecessary

procedures in 36% of coronary lesions investigated. • IVUS MLA criteria alone cannot predict the result of FFR

measurement.• The FFR value and IVUS-measured parameters are

complementary and not competitive.

Other study

• FAME 2 Study• conclusively address the question of whether performing PCI

in lesions with abnormal FFR results leads to better outcome compared with deferring PCI, a subsequent clinical study, FAME 2, was conducted.

FAMOUS-NSTEMI

Algorithm of functional angioplasty

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