This document provides an overview of evaluating myocardial and coronary blood flow and its role in coronary intervention. It discusses fundamental concepts of coronary physiology and myocardial blood flow that are now used in clinical practice. Physiologic lesion assessment using tools like fractional flow reserve (FFR) and instantaneous wave-free ratio (iFR) have become routine before percutaneous coronary intervention (PCI) to determine the true ischemic potential beyond angiography limitations. Studies demonstrated FFR-guided PCI resulted in fewer stents, less contrast, lower costs and shorter hospital stays compared to angiography-guided PCI. While FFR remains the gold standard, iFR was found to be non-inferior in major adverse cardiac event rates. Coronary flow reserve (

1. EVALUATION OF MYOCARDIAL & CORONARY BLOOD FLOW
& ITS ROLE IN CORONARY INTERVENTION
PRESENTED BY : DR SAYAR AHMAD PANDIT ,SR2 CARDIOLOGY LPSIC .
DATED: 1 MARCH 2023

2. INTRODUCTION
 Fundamental concepts of coronary physiology and myocardial blood flow, once the subject of research
studies, are now used in daily clinical practice.
 The adoption of invasive coronary physiologic lesion assessment before percutaneous coronary
intervention (PCI) has become routine in many catheterization laboratories (cath lab).
 The rationale for the use of physiology in the cath lab is the necessity to overcome the limitation of
angiography in reflecting the true ischemic potential of a coronary luminal narrowing.

3. HOW MUCH ENERGY HEART UTILIZE ?
 The total metabolism of an arrested, quiescent heart is approximately 1.5 mL/min per 100 g, as required
to support the physiologic processes not directly associated with contraction.
 In contrast, a beating canine heart has MVO2 ranging from 8 to 15 mL/min per 100 g.
 At rest, the rate of force development -60% of myocardial energy use;
• myocardial relaxation -15% of energy use;
• electrical activity accounts for 3% to 5%; and
• basal cellular metabolism accounts for the remaining 20% of energy use.
 Any compromise in substrate availability causes the myocardium to minimize energy expenditure on
mechanical work
• divert the remaining high-energy substrates for the continued maintenance of cellular integrity, thus
setting the stage for myocardial “hibernation.”

4. DETERMINANTS OF MVO2
 Heart rate
 Contractile state
 Tension development
 Activation
 Depolarization
 Direct metabolic effect of catecholamines
 Family history of coronary artery disease
 Fatty acid uptake
 Maintenance of active state
 Maintenance of cell viability in basal state
 Muscle shortening against a load (the Fenn
effect)

5. MEASUREMENT OF MYOCARDIAL METABOLISM
 Measurement of myocardial metabolism may be performed:
 noninvasively (e.g., positron emission tomography scanning) or
 invasively by transmyocardial sampling techniques that involve acquisition of simultaneous arterial and
coronary venous (e.g., coronary sinus) blood.

6. DIAGRAM OF CORONARY RESISTANCES

7. REGULATION OF CORONARY CIRCULATION

8. MEDIATORS OF CORONARY VASODILATION

9. CORONARY FLOW RESERVE

10. OTHER THAN STENOSIS ,WHAT FACTORS REDUCE CFR?

11. SCHEMATIC DEPICTION OF DOPPLER FLOW WIRE

12. TRANSLESION PRESSURE MEASUREMENT

13. AGENTS USED FOR INDUCTION OF HYPEREMIA

14. SPECTRAL DOPPLER FLOW VELOCITY -BASELINE/ HYPEREMIA (CFR)

15. PRESSURE TRACINGS ACROSS STENOSIS (FFR )

16. PRESSURE DAMPING / DEEP SEATED GUIDE CATHETER

17. PITFALLS OF FFR

18. ACCELERATION AND DECELERATION WAVES WITHIN CORONARY
SYSTEM

19. IFR(ADVISE STUDY) / ADENOSINE INDEPENDENT INDEX OF
STENOSIS SEVERITY

20. ADVISE-II STUDY (IFR VS FFR), N=157 STENOSIS
Good
comparison b/w
IFR and FFR
assessment

21. ROLE OF FFR/ IFR IN CORONARY INTERVENTION

22. DEFER STUDY ,N=325
Low incidence
of cardiac
events in
patients with
negative FFR (>
0.75) and
without pci

23. FAME TRIAL ,N=1005, FFR-PCI VS ANGIO-PCI IN MULTI VESSEL CAD
With FFR:
Fewer stents
Less contrast
Lower cost
Shorter stay in hospital

24. BENEFIT OF PCI IF ABNORMAL FFR- FAME 2 STUDY, N=888

25. FAME 11
At 5 yrs Less urgent
revascularization
needed in PCI
group 6.3% (vs
21.1% MT)

26. CLINICAL VIGNETTES

27. 68 male,
typical
angina,
CAD risk
factors,
ECG
STRESS
test
positive

28. 68 male,
typical angina ,
CAD risk
factors, ECG
stress positive

30. LM STENOSIS : FFR >0.8 ASSOCIATED WITH EXCELLENT LONG TERM
OUTCOME HAMILOS ET. AL
FFR> 0.8 MT
FFR <0.8 REVASCULARISATION

31. Intermediately
severe LM
stenosis, LAO
view
LM not
hemodynamical
ly significant

32. EVIDENCES

33. OVERESTIMATION OF LM FFR IN PRESENCE OF 2ND LESION
DOWNSTREAM
1. Severity of additional
lesion
2.Mass of myocardium distal
to 2nd lesion

34. FFR WOULD BE HIGH IF COLLATERAL /BYPASSS GRAFT

35. FFR IN CASE OF SERIAL LESIONS
RAO oblique, LAD
with multiple serial
lesions
LAO
Focal change
in pressure
gradient at
Lesion 3

37. IS IFR NON INFERIOR TO FFR IN TERMS OF MACE?

38. DEFINE REAL STUDY , N 484 –IFR IN DECISION MAKING

39. IFR MORE ACCURATELY PREDICTS PHYSIOLOGICAL RESULTS AFTER
PCI OF ONE STENOSIS IN SERIAL LESIONS

41. CFR MEASUREMENT- CORONARY DOPPLER FLOW VELOCITY

42. CFR- GUIDEWIRE THERMODILUTION TECHNIQUE

43. CFR
 Normal >3
 Hypertension/ T2DM/ Hyperlipidemia 2.7± 0.64
 CFR< 2.0 associated with inducible myocardial ischemia on stress testing
 Changes in heart rate , BP and contractility alter CFR by changing resting basal flow or maximal
hyperemic flow

44. INVASIVE PHYSIOLOGIC INDICES

45. Summary/Recommendations

46. Thank you