FFR QFR CFR and coronary flow reserve ppt

Coronary physiology assessment by invasive and non invasive methods.

1. pHYSIOLOGICAL LESION ASSESSMENT FFR, I FR – Concept & technical tips Presented by Dr Apoorva Under the guidance Dr S S Kothari sir Dr Gajendra Dubey sir Dr Anand Shukla sir Dr Dinesh Joshi sir Dr Jignesh Vanani sir Dr Pankaj Singh sir

2. Text Introduction Coronary revascularization is warranted only if a patient has one or more coronary artery stenoses that are hemodynamically important. Large randomized studies have shown that FFR is superior to angiographic assessment for this purpose. Studies have also shown that resting indices have diagnostic accuracy similar to that of FFR as independent measures of ischemia.

3. Fractional flow reserve Ffr

4. introduction Myocardial perfusion pressure, normally the diastolic coronary pressure, equals aortic pressure minus the left ventricular diastolic pressure or CVP. FFR is the “ratio of the maximal myocardial blood flow in the presence of a stenosis relative to expected normal flow in the absence of a stenosis.”

5. Concept If flow increases —> more drop in pressure past the stenosi s. At maximal hyperaemia , flow increases and thus Pd further drops. Flow rises, but less than the potential rise had there not been a stenosis. Eg ., flow increases x2, instead of x4 without a stenosis.

6. Larger territory Higher flow at rest and esp ecially with hyperaemia More Pd drop and flow drop past the stenosis. For the same stenosis severity ( eg . 80%), a proximal LAD stenosis is more likely to be significant than a small diagonal stenosis. Collateral supply Also, for the same stenosis severity, length increases the significance of a stenosis ( Poiseuille law ).

7. Significance FFR<=0.80 identifies ischemia with a very high specificity (100% if <0.75). FFR>0.80: PCI should be deferred. FAME TRIAL : patients with MVD undergoing PCI were randomised to angio guidance vs FFR guidance with deferral of stenting if FFR>0.80. FFR guidance improved combined MACE. FFR<=0.80: does not mandate stenting if angina atypical/infrequent ( FAME 2 - FFR did not improve hard outcomes, death or MI at 3, 5 yrs , but improved angina and future revascularizations) Severe exertion angina + FFR <=0.8 = STENTING

8. Trials Fame trial- ffr arm 50-70% stenoses : 35% FFR significant 70-90% stenoses : 80% FFR significant >90% stenoses : ~all significant Deferral is safe for FFR>0.80. The rate of MI occurring in a deferred lesion with FFR>0.80 was only 0.2% at 2 yrs in FAME 1 . But , summation MI risk from all non significant lesions was still ~2% at 8 months and 8% at 5 yrs in FAME 2 . Rate of MI from deferred lesion with FFR<0.80 was ~2-3% per yr in FAME 2 , but still no overall MI/death benefit from stenting.

9. LOOK FOR THIS!

10. Instantaneous wave-free ratio Ifr

11. Text Ifr : instantaneous wave-free ratio “ Instantaneous pressure ratio, across a stenosis during the wave-free period, when resistance is naturally constant and minimised in the cardiac cycle.”

12. concept iFR uses the concept that micro coronary resistance is lowest and flow is highest in diastole. In diastole, Pd/Pa ratio at rest drops the most and approximates flow ratio, even without using adenosine. iFR is a resting diastolic ratio. The cutoff of iFR significance is 0.89 2 large trials ( FLAIR & iFR -SWEDEHEART 2017 ) showed that iFR guided PCI was associated with long term outcomes similar to FFR-guided PCI. ~25% less lesions considered significant and s t ented by iFR (29% vs 37%) . No difference in death, MI or unplanned revascularizations at 5yrs

13. Text Ifr-ffr discrepancies iFR may underestimate the severity of arteries with very large territories or healthy microcirculation, because the increase of flow in those lesions with /without hyperaemia is massive and thus, FFR would drop far more than a resting ratio. Hence, more lesions are significant by FFR than by iFR , but similar long term outcomes ( FIGARO Study ) . LM may be better assessed by FFR. RCA may be better assessed by FFR. Low resting flow states ,may cause iFR -/FFR+

14. Text FFR-/ iFR + less common, but is seen in patients with dysfunctional microvasculature /less hyperaemic response with adenosine (diffuse disease, elderly, smokers, CKD, diabetes). ~20% discordance between iFR and FFR (FIGARO study): FFR+/ iFR - (14%, more so in RCA 23%) or FFR-/ iFR + (6%)

15. Method, errors and technical tips

16. Equipment Pressure monitoring guide wire Specially constructed 0.014” wire Pressure sensor incorporated into distal end, at 3 cm from tip Piezo-electric technology Eg . St.Jude Medical Phillips Volcano

17. Method Instructions 6 Fr guide. NTG 100-200 mcg to eliminate epicardial vasospasm. Equalize Pa and Pd with wire sensor just at the guide tip. Place sensor 2-3 cm distal to the lesion, re-flush the catheter, not too distal. For FFR: hyperaemia with iv adenosine, large iv access (vs ic adenosine). For iFR : avoid measurements <30 sec after contrast flushing. Disengage guide during measurements. If borderline FFR, pull back and verify that Pa and Pd are equal (no transducer drift).

18. Hyperaemia

19. Pressure equalization

20. Errors Pressure drift

21. Errors

22. One study (CCI 2015) has shown that even if you are not ventricularized , it is always good to disengage the guide during FFR measurement, as guide may be slightly obstructive —> you get more flow and more FFR drop with disengagement. The mean delta FFR after disengagement was 0.05+/-0.04 although most patients did not have obvious ventricularization .

23. IVUS= 4.5 mm2, but FFR was 0.91

24. ERRORS

25. DIFFERENT SCENARIOS FFR/IFR

26. 1. Serial stenoses concept

27. iFR >> FFR

28. 2. Diffuse disease If FFR <=0.80 but pressure pullback reveals a gradual decline in pressure without a focal drop, the patient may not be served by PCI (but may be by CABG). This may be seen in patients with mild or moderate diffuse disease and small coronary arteries: 8-10% of arteries with mild diffuse lesions have a graded continuous fall in pressure along the arterial length with FFR<0.75 , explaining myocardial schema and angina without angiographically obstructive disease.

29. 3 . Left main disease Hamilos M et al. Circ 2009

30. With MLA <6 mm2, 22.4% had FFR-/iFR- With MLA >6 mm2, 13.6% had FFR+/iFR+ Best to use both iFR and FFR in LM +/- IVUS. Revascularize if 2/3 are significant

31. 4. Non-culprit artery in nstemi / stemi

32. 5 . Aortic stenosis Yousif Ahmad et al. JACC Cardiovasc Interv.2018 October

33. Text Best used in: FFR iFR LM/ prox LAD Serial disease Young patient with focal disease Aortic stenosis Healthy microcirculation Microvascular dysfunction

34. 6. Post-stenting ffr

35. Text ffr -guided cabg

36. Falsely - FFR Truly - FFR Falsely + FFR Guide not disengaged Side hole guide Small territory Diffuse disease Severe hypotension Old MI with little viable tissue Lack of equalisation Pressure drift Advanced heart failure Severe stable microvascular disease Accordion effect Insufficient hyperaemia

37. Thank you!