1. Beyond CAG- IVUS and FFR Dr Frijo Jose A

3. CAG – Extensively used – Entire cor anatomy, including small & distal vessels – Helpful in clinical decision making 1.Eccentricity 2.Vascular remodelling 3.Relative % stenosis 4.Reference segment assessment 5.Limited correlation with physiology 6.Post PTCA/dissec

4. 1. Eccentricity of lesions

5. In coronaries with atherosclerosis, the lumen is often irregular and non-circular

6. Topol, E. J. et al. Circulation 1995;92:2333-2342 Schematic representation of an important limitation of projection imaging

7. Pitfall: lesion eccentricity

9. Topol, E. J. et al. Circulation 1995;92:2333-2342 Angiographically unrecognized left main coronary artery disease

10. 2. Vascular Remodelling (Glagov’s phenomenon)

14. Topol, E. J. et al. Circulation 1995;92:2333-2342 Effect of coronary remodeling

15. These plaques are particularly prone to rupture. Missed by angiography.

16. 3. Reference seg assessment & Relative % stenosis

17. Topol, E. J. et al. Circulation 1995;92:2333-2342 Concealment of severe coronary disease by diffuse concentric involvement

18. IVUS Imaging 2D Cross-Sectional Imaging

19. 4.Limited correlation with physiology and pre-stenting

20. Chest pain with normal coronaries 50 % have plaques on IVUS, which might have ruptured to cause the chest pain

21. IVUS before PCI Baseline plaque composition Vessel size Confirm CAG severity

22. Lesions of uncertain severity- IVUS can solve- (changed original provisional decision in 20%) Intermediate severity (40-75%)- FFR can provide further information (>0.75- favorable outcome with medical Rx) LMCA obstruction- – Contrast in cusps can obscure the ostium – Streaming of contrast can falsely suggest narrowing – There may not be a normal reference segment – Branch vessels overlap distal part- stenosis is masked In ostial lesions, IVUS provides information about whether there is a lesion at all and whether the lesion is truly ostial or not

23. Quantitation of atheroma (slight overestimation)

26. Intimal thickness ≥0.5 mm - abnormal and indicative of atherosclerosis Total atheroma volume- motorized device pulls back transducer at 0.5 mm/sec. From the slices so obtained, TAV is found by the Simpson’s rule Most plaques are eccentric- max thickness is more than twice the minimum thickness

27. Fatty streaks are not clearly identified. Atheroma- fibrosis and calcification are clearly identified, but hypoechoic part may be lipid, thrombus or necrotic degeneration. Radiofrequency analysis superimposed on IVUS helps to clarify the situation. More sensitive than fluoroscopy to detect calcification. Positive remodeling- landmark study by Glagov- initially there is increase in plaque area without decrease in luminal area- due to increase in EEM (enclosed) area.

28. large, soft, lipid-laden atheroma with a thin fibrous cap is seen (arrows). It is eccentric, involving only approximately 50 percent of the vessel wall shows a circumferential atheroma with an area of focal calcification is evident (arrow).

29. ACS- – Less obstructive plaques are much more common – More lipid pool – Thin fibrous cap – Ruptured cap – Superimposed thrombus – Multiple sites of rupture

30. Potentially unstable coronary lesion Echolucent

31. 5. post-stenting and dissection

32. Initial procedural results Quantifying late intimal hyperplasia

33. Topol, E. J. et al. Circulation 1995;92:2333-2342 Overestimation of lumen gain by angiography after balloon angioplasty

34. IVUS – mechanisms of lumen gain by balloon dilation- – Fracture of the plaque – Plaque is redistributed axially – Arterial wall stretching

35. IVUS and stenting- – Pioneering report by Colombo – High chance of incomplete stent apposition with usual dilation- not seen by check CAG - contrast flows outside the porous stent - fills space provided by the vessel which has been passively dilated by the balloon dilation. Higher pressure dilation or larger balloon size solves problem – Even aft high pressure dilation, when IVUS was done, additional procedures done in 20- 40 %

36. – STARS study- decreased restenosis in IVUS guided stenting. TULIP study- decreased restenosis only in long and diffuse lesions. – Stent to reference area ratio does not predict TVR. Stent area of 9 mm2 or more predicts freedom from restenosis. – Very useful in suspected dissection after stenting- to know the full length of the dissection. – Useful to discern the cause of “persistent haziness” after stenting. – Restenosis mech- usually neo-intimal proliferation. Also, restenosis at the margins. No decrease in the stent area- stents can withstand remodeling.

37. Late stent malapposition

38. IVUS – Tomographic views – Vessel wall + lumen visualization – Validated quantitative software – Plaque characterization – Need to instrument vessels – Limited to proximal segments – Bifurcation lesions – Cost – Not as well validated for clinical decision making – Limited correlation with physiology – Not always perpendicular to vessel axis

39. IVUS Pitfall : Imaging plane not perpendicular to vessel axis

40. ACC/AHA Recommendations for Coronary IVUS Class II A 1. Evaluation of lesion severity at a location difficult to image by angiography in patients with a positive functional study and a suspected flow-limiting stenosis 2. Assessment of a suboptimal angiographic result after coronary intervention 3. Diagnostic and management of coronary disease after cardiac transplantation

41. Absolute flow reserve – Drugs- intracoronary papaverine, intracoronary adenosine, intravenous dipyridamole – Ratio of maximum to resting flow rate – Below 2- causes stress induced ischemia – Reduction may be due to ↑resting flow also – ↓ in severe stenosis and microcirculatory abn

42. Relative flow reserve – Maximum exercise/pharmacological dilation – Minimum threshold of 0.8 – Inaccurate in multivessel disease – Inaccurate in microcirculatory disease

43. Fractional flow reserve – During maximum vasodilation – Mean cor pressure/mean Ao pressure – Unaffected by alteration in resting flow – Can immediately assess importance of a lesion for guiding intervention – Considerable prognostic information – FFR more than 0.75- excellent outcome with deferred rather than prophylactic intervention – Affected by microcirculatory disease – Most direct way to assess physiological significance of a lesion

44. Simultaneous measurement of pressure in aorta and distal LAD at rest

45. Simultaneous measurement of pressure in aorta and distal LAD following intracoronary adenosine

48. Clinical uses of FFR 1. Determining the hemodynamic significance of CAG intermediate lesions: Pijls et al - cutoff 0.75 detected ischemia – sensitivity- 88%, specificity- 100%, diagnostic accuracy- 93% DEFER - moderate CAD + FFR>0.75 - PCI v/s medical – PCI event rate > medical event rate

49. Clinical uses of FFR 2. Determining success of PCI: Multicenter registry - FFR determined immediately after stenting – most signi independent variable related to future events

50. Clinical uses of FFR 3. Determining significance of LMCA lesions: Bech et al- 54pts (29/12)- equivocal LMCA Medical - 24 pts with FFRs >0.75 CABG - 30 pts with FFR <0.75 Survival – medical- 100%, CABG- 97%

51. Clinical uses of FFR 4. Determining the significance of multiple stenoses in the same coronary artery: FFR can be used to “map” the hemodynamic effects of multiple stenoses in the same vessel FAME (1005pts)- clinical outcomes after PCI on CAG v/s CAG+ FFR in multivessel disease FFR gp- 37% of PCI indented lesns- FFR >0.80 1 yr- composite event rate -18.3% CAG-guided gp V/S 13.2% CAG+FFR-guided group

52. Recommendations for Use of Fractional Flow Reserve Class IIa Can be useful to determine whether PCI of a specific cor lesion is warranted Can be useful as an alternative to performing noninvasive functional testing (eg, when the functional study is absent or ambiguous) to determine whether an intervention is warranted In the assessment of the effects of intermediate cor stenoses (30% to 70% luminal narrowing) in pts with anginal symptoms

53. Case study