Fractional flow reserve (FFR) is usually estimated invasively using a Doppler flow wire introduced into the coronary artery and measuring the pressure drop across the coronary stenosis during maximal hyperemia induced by adenosine. FFR has been shown to be of great significance while assessing the severity of borderline coronary stenosis in deciding the need for coronary angioplasty. Fractional flow reserve estimated by computed tomographic angiography (FFRCT) is a novel technique of getting similar information non invasively.FFR with CT angiography has been shown to be superior to conventional CT coronary angiography and it has been shown to have a high negative predictive value of 91.6% . FFRCT estimation is also called non invasive fractional flow reserve derived from coronary CT angiography .
The PLATFORM study assessed the quality of life and economic outcomes of using FFR with CT angiography . The study involved 584 patients with atypical angina and 49% pretest probability of coronary artery disease. They documented that FFRCT based strategy was associated with less resource utilization and cost at 90 days than invasive evaluation. This was even after setting the cost weight of FFRCT to 7 times that of CT coronary angiography. FFRCT was also associated with better quality of life than conventional non invasive testing.
A meta-analysis showed that CT coronary angiography had a pooled sensitivity of 0.92 and specificity of 0.43. FFRCT increased this specificity to 0.72 so that positive predictive value improved from 0.56 to 0.70. There was no improvement in sensitivity .
Excellent correlation between FFR and FFRCT while assessing serial coronary stenoses have also been documented, with correlation coefficient of 0.92, in a study involving 18 vessels with serial coronary lesions and stable angina pectoris .
Another meta-analysis evaluated 16 studies published between 2011 and 2019. The analysis had data on 1852 patients and 2731 vessels . The authors concluded that FFRCT had higher specificity for anatomical and physiological assessment of coronary stenosis than CT coronary angiography. FFRCT was considered to be a viable alternative to invasive measurement of FFR for the detection and exclusion of significant coronary lesions which cause ischemia.
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Min JK, Taylor CA, Achenbach S, Koo BK, Leipsic J, Nørgaard BL, Pijls NJ, De Bruyne B. Noninvasive Fractional Flow Reserve Derived From Coronary CT Angiography: Clinical Data and Scientific Principles. JACC Cardiovasc Imaging. 2015 Oct;8(10):1209-22.
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