Coronary Hemodynamics And Fractional Flow Reserve Flashcards by Riyanna Day

What is the primary determinant of coronary blood flow control?
a) Blood pressure
b) Heart rate
c) Local metabolites like adenosine and nitric oxide
d) Myocardial contractility

c) Local metabolites like adenosine and nitric oxide

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What does the coronary flow reserve (CFR) measure?
a) The ratio of maximal coronary flow to resting coronary flow
b) The pressure difference across a coronary artery
c) The heart rate during maximal hyperemia
d) The change in blood pressure during exercise

a) The ratio of maximal coronary flow to resting coronary flow

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Which of the following is a physiological cause of decreased CFR?
a) Increased myocardial contractility
b) Progressive obstruction of a coronary artery
c) Increased heart rate
d) Decreased systemic blood pressure

b) Progressive obstruction of a coronary artery

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Fractional Flow Reserve (FFR) is based on which principle?
a) Changes in heart rate are proportional to blood flow
b) Resistance changes with vessel diameter
c) Changes in pressure are proportional to changes in blood flow when resistance is constant
d) Blood flow remains constant despite pressure changes

c) Changes in pressure are proportional to changes in blood flow when resistance is constant

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What is the current FFR threshold used in clinical practice?
a) 0.75
b) 0.80
c) 0.85
d) 1.00

b) 0.80

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Which of the following is NOT a scenario in which FFR is shown to be useful?
a) Left main lesions
b) Nonculprit lesions in acute coronary syndromes
c) Bifurcation lesions
d) Single-vessel coronary artery disease

d) Single-vessel coronary artery disease

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What does FFR correlate with?
a) Maximum myocardial blood flow in the absence of stenosis
b) The ratio of maximal blood flow to basal blood flow
c) Maximum myocardial blood flow in the presence of stenosis compared to normal vessel flow
d) The difference between resting and maximal coronary pressure

c) Maximum myocardial blood flow in the presence of stenosis compared to normal vessel flow

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What percentage of myocardial oxygen demand is used by systolic wall tension?
a) 50%
b) 30%
c) 75%
d) 15%

b) 30%

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Which of the following is NOT a determinant of myocardial oxygen demand?
a) Preload
b) Afterload
c) Myocardial wall thickness
d) Arterial-venous oxygen difference

d) Arterial-venous oxygen difference

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How much of the cardiac output does the heart receive through the coronary arteries when at rest?
a) 10%
b) 25%
c) 5%
d) 50%

c) 5%

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What is the approximate basal oxygen extraction rate of the myocardium?
a) 50%
b) 25%
c) 75%
d) 90%

c) 75%

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What is unique about the oxygen consumption of the heart compared to other organs?
a) The heart has the lowest oxygen consumption per tissue mass
b) The heart has the highest arterial-venous oxygen difference
c) The heart receives the most oxygenated blood
d) The heart’s oxygen consumption equals that of skeletal muscle at rest

b) The heart has the highest arterial-venous oxygen difference

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Which of the following factors directly affects wall tension?
a) Basal metabolic rate
b) End-diastolic volume
c) Oxygen saturation in the coronary sinus
d) Oxygen extraction rate

b) End-diastolic volume

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Under basal conditions, the myocardium extracts approximately how much of the delivered oxygen?
a) 90%
b) 50%
c) 75%
d) 30%

c) 75%

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How does the heart primarily meet increased metabolic demands?
a) Increasing oxygen extraction
b) Shifting to anaerobic metabolism
c) Increasing coronary blood flow
d) Decreasing basal metabolic rate

c) Increasing coronary blood flow

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What is the primary controller of coronary blood flow in the absence of obstructive coronary artery disease (CAD)?
a) Changes in oxygen consumption
b) Resistance in the microvasculature (small arteries and arterioles)
c) Arterial-venous oxygen difference
d) Heart rate and preload

b) Resistance in the microvasculature (small arteries and arterioles)

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What happens to microvascular resistance in the presence of hemodynamically significant epicardial disease?
a) It decreases at baseline to maintain coronary blood flow
b) It increases to prevent further obstruction
c) It remains unchanged
d) It increases to support greater oxygen extraction

a) It decreases at baseline to maintain coronary blood flow

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What limits the myocardium’s ability to increase coronary flow in response to increased demand when there is obstructive epicardial disease?
a) Decreased microvascular resistance at baseline
b) Decreased coronary sinus oxygen saturation
c) Increased heart rate and afterload
d) Increased anaerobic metabolism

a) Decreased microvascular resistance at baseline

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Why can’t the heart significantly increase oxygen extraction during increased demand?
a) The heart already extracts a high percentage of delivered oxygen
b) The heart relies primarily on anaerobic metabolism
c) The coronary arteries limit oxygen extraction
d) The basal metabolic rate limits oxygen consumption

a) The heart already extracts a high percentage of delivered oxygen

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During which phase of the cardiac cycle does coronary blood flow primarily occur?
a) Systole
b) Diastole
c) Both systole and diastole equally
d) Isovolumetric contraction

b) Diastole

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Which coronary artery has the greatest diastolic predominance in blood flow?
a) Right coronary artery
b) Left anterior descending artery
c) Circumflex artery
d) Left circumflex artery

b) Left anterior descending artery

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What is the reason for greater diastolic predominance of flow in the left coronary artery compared to the right?
a) The left ventricle has lower compressive forces than the right ventricle
b) The compressive forces of the left ventricle are greater than those of the right ventricle
c) The right ventricle is more relaxed during diastole
d) The right coronary artery has more branches

b) The compressive forces of the left ventricle are greater than those of the right ventricle

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What percentage of blood flow in the left anterior descending artery occurs during diastole?
a) 50%
b) 100%
c) 85%
d) 25%

c) 85%

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Why does myocardial ischemia worsen during tachycardia?
a) Increased oxygen demand is met by decreased coronary blood flow
b) Diastole is shortened, reducing oxygen supply while demand increases
c) Systole is prolonged, reducing overall coronary blood flow
d) The right ventricle compresses the coronary arteries more during tachycardia

b) Diastole is shortened, reducing oxygen supply while demand increases

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How does blood flow in the right coronary artery differ from the left anterior descending artery? a) Flow in the right coronary artery occurs more in systole than in diastole b) Right coronary artery flow is more or less equal in systole and diastole c) Right coronary artery flow is greater during diastole than in systole d) Right coronary artery flow is minimal compared to the left

b) Right coronary artery flow is more or less equal in systole and diastole

What is the term used to describe the heart’s ability to maintain coronary blood flow despite changes in perfusion pressure? a) Afterload regulation b) Vasoconstriction c) Autoregulation d) Contractility control

c) Autoregulation

Over what range of perfusion pressures does autoregulation maintain consistent coronary flow? a) 40 to 120 mm Hg b) 60 to 150 mm Hg c) 50 to 140 mm Hg d) 70 to 160 mm Hg

b) 60 to 150 mm Hg

What happens to coronary blood flow in the setting of maximum vasodilation of resistance vessels? a) It is maintained by autoregulation b) It varies linearly with perfusion pressure c) It decreases despite increased perfusion pressure d) It becomes independent of perfusion pressure

b) It varies linearly with perfusion pressure

Why is autoregulation particularly important in the presence of epicardial coronary stenoses? a) It ensures the heart reduces oxygen demand b) It helps maintain coronary blood flow despite decreased perfusion pressures c) It increases resistance in the coronary arteries d) It limits blood flow to areas without stenosis

b) It helps maintain coronary blood flow despite decreased perfusion pressures

What is the effect of coronary resistance vessel vasodilation on autoregulation? a) Autoregulation becomes more effective b) Autoregulation is overridden, and blood flow depends on perfusion pressure c) Autoregulation continues unaffected d) Blood flow decreases due to increased vascular resistance

b) Autoregulation is overridden, and blood flow depends on perfusion pressure

What would happen to coronary blood flow if perfusion pressures drop below 60 mm Hg without autoregulation? a) Coronary blood flow would remain stable b) Coronary blood flow would decrease c) Coronary blood flow would increase d) Blood flow would cease entirely

b) Coronary blood flow would decrease

What is the term for the ratio of maximal coronary flow to resting coronary blood flow? a) Fractional Flow Reserve (FFR) b) Coronary Flow Reserve (CFR) c) Oxygen Extraction Ratio (OER) d) Cardiac Output Reserve (COR)

b) Coronary Flow Reserve (CFR)

What primarily controls coronary blood flow? a) Neural influences b) Release of local metabolites like adenosine or nitric oxide c) Changes in heart rate d) Blood pressure fluctuations

b) Release of local metabolites like adenosine or nitric oxide

Which of the following is the most potent coronary vasodilator? a) Acidosis b) Hypercapnia c) Hypoxia d) Neural stimulation

c) Hypoxia

How is maximal coronary blood flow typically achieved in clinical medicine? a) By increasing blood pressure b) Through intracoronary or intravenous administration of adenosine c) By inducing hypercapnia d) By neural stimulation

b) Through intracoronary or intravenous administration of adenosine

Which of the following agents is NOT typically used to increase coronary blood flow? a) Papaverine b) Nitroglycerin c) Dopamine d) Regadenoson

c) Dopamine

Which factor has a relatively minor influence on coronary blood flow? a) Neural influences b) Local metabolite release c) Hypoxia d) Vasodilator agents

a) Neural influences

What happens to the ratio of maximal blood flow to basal blood flow with progressive obstruction of an epicardial coronary artery? a) It increases b) It decreases c) It remains unchanged d) It fluctuates unpredictably

b) It decreases

What tool is used to measure coronary flow reserve (CFR) in clinical practice? a) A Doppler ultrasound b) A coronary catheter with a pressure transducer c) A 0.014-inch guidewire with a 12-MHz piezoelectric transducer d) An external EKG monitor

c) A 0.014-inch guidewire with a 12-MHz piezoelectric transducer

Where is the guidewire placed when measuring CFR? a) In the aorta b) Proximal to the coronary lesion c) Distal to the coronary lesion d) In the left ventricle

c) Distal to the coronary lesion

What is measured to calculate CFR? a) Coronary artery diameter b) Phasic spectral blood flow velocity c) Coronary pressure gradient d) Heart rate and blood pressure

b) Phasic spectral blood flow velocity

Which assumption is made when using velocity in place of flow to calculate CFR? a) The coronary artery diameter changes significantly b) The coronary artery diameter remains relatively constant c) Blood pressure remains constant during the procedure d) The patient’s heart rate is stable

b) The coronary artery diameter remains relatively constant

What is typically used as a hyperemic stimulus to measure maximal coronary blood flow? a) Papaverine b) Nitroglycerin c) Adenosine d) Contrast dye

c) Adenosine

What is one reason the Doppler wire is not widely used despite its theoretical advantages? a) It is too expensive for clinical use b) It requires advanced training to operate c) Several conditions other than atherosclerosis can affect CFR d) It is not effective in all patient populations

c) Several conditions other than atherosclerosis can affect CFR

Which of the following conditions can raise basal coronary blood flow? a) Diabetes mellitus b) Ventricular hypertrophy c) Tachycardia d) Atherosclerosis

c) Tachycardia

What is required for accurate measurements when using a Doppler flow wire? a) The wire must be inserted at high pressure b) Correct positioning of the Doppler flow wire c) Continuous monitoring of blood pressure d) The patient must be at rest

b) Correct positioning of the Doppler flow wire

How should the transducer of the Doppler flow wire be positioned to avoid vessel wall artifacts? a) Pointing directly at the vessel wall b) Pointing away from the flow stream c) Pointing away from the vessel wall and into the flow stream d) Perpendicular to the flow direction

c) Pointing away from the vessel wall and into the flow stream

What indicators can be used to assess the proper positioning of the Doppler flow wire? a) Blood pressure and heart rate b) Gray-scale signal amplitude and peak velocity c) The patient’s symptoms d) Contrast dye infusion rates

b) Gray-scale signal amplitude and peak velocity

What is a limitation regarding the interpretation of CFR values? a) There is a lack of technology to measure CFR accurately b) There is a lack of consensus on what CFR value indicates a hemodynamically significant lesion c) CFR values cannot be replicated in clinical studies d) There are no established cutoff values for ischemia-causing lesions

b) There is a lack of consensus on what CFR value indicates a hemodynamically significant lesion

In various clinical studies, what cutoff values of CFR have been used to determine ischemia-causing lesions? a) 0.5 to 1.0 b) 1.0 to 1.5 c) 1.6 to 2.5 d) 2.6 to 3.0

c) 1.6 to 2.5

What does the concept of "relative CFR" (rCFR) help to differentiate? a) Normal and abnormal blood flow b) Epicardial lesions and microvascular dysfunction c) Resting and maximal coronary flow d) Systolic and diastolic blood pressure

b) Epicardial lesions and microvascular dysfunction

How is rCFR determined? a) By measuring heart rate variability b) By measuring CFR in a coronary artery without epicardial disease c) By comparing blood flow in the left and right coronary arteries d) By assessing the patient’s symptoms

b) By measuring CFR in a coronary artery without epicardial disease

What does an abnormal CFR in a vessel without disease imply? a) Normal coronary function b) Impaired microvasculature c) Severe epicardial disease d) Increased coronary blood flow

b) Impaired microvasculature

What is one caveat of using rCFR? a) It is always accurate regardless of conditions b) It requires a vessel without significant epicardial disease c) It is less effective than traditional CFR measurement d) It can only be used in patients with a history of MI

b) It requires a vessel without significant epicardial disease

What assumption is made about microvasculature function when using rCFR? a) It is affected by heart rate b) It is consistent across different vascular beds c) It is always impaired in patients with previous MI d) It is independent of any epicardial conditions

b) It is consistent across different vascular beds

Why might the assumption of consistent microvascular function across different vascular beds be problematic? a) It simplifies the assessment process b) Microvascular function can vary, especially in cases of previous myocardial infarction c) It is not relevant in patients without epicardial disease d) It requires more advanced imaging techniques

b) Microvascular function can vary, especially in cases of previous myocardial infarction

What is the basic principle of fractional flow reserve (FFR)? a) Changes in flow are constant regardless of pressure b) Changes in pressure are proportional to changes in flow when resistance is constant c) Pressure and flow are inversely related d) Resistance varies with flow changes

b) Changes in pressure are proportional to changes in flow when resistance is constant

Since when has the concept of using the pressure gradient to assess stenosis severity been in use? a) Since the introduction of angioplasty b) Since the early days of endovascular intervention c) Since the development of coronary bypass surgery d) Since the use of stents in coronary arteries

b) Since the early days of endovascular intervention

What significant finding was reported by Gruentzig regarding percutaneous transluminal coronary angioplasty? a) An increase in translesional pressure gradients b) A decrease in translesional pressure gradients from 58 to 19 mm Hg in successful cases c) The use of fluid-filled tubes for pressure measurement d) The failure of the procedure in most patients

b) A decrease in translesional pressure gradients from 58 to 19 mm Hg in successful cases

What issue did early attempts to measure pressures distal to a stenosis encounter? a) The inability to measure pressures accurately b) The use of fluid-filled tubes increased the translesional gradient due to their size c) There were no standardized methods for measurement d) Patients often experienced severe complications

b) The use of fluid-filled tubes increased the translesional gradient due to their size

How did the advent of a pressure transducer mounted on a 0.014-inch angioplasty wire improve pressure measurements? a) It allowed for non-invasive pressure assessments b) It eliminated the need for any pressure measurements c) It overcame difficulties associated with fluid-filled tubes d) It reduced the size of the angioplasty wire

c) It overcame difficulties associated with fluid-filled tubes

What concept was introduced with the development of the pressure transducer mounted on the angioplasty wire? a) Angiographic pressure measurement b) Pressure-derived fractional flow reserve (FFR) c) Direct coronary pressure measurement d) Invasive hemodynamic monitoring

b) Pressure-derived fractional flow reserve (FFR)

b) A decrease in translesional pressure gradients from 58 to 19 mm Hg in successful cases

What is the relationship described by Ohm's law in terms of flow? a) Flow = pressure + resistance b) Flow = pressure × resistance c) Flow = pressure / resistance d) Flow = resistance / pressure

c) Flow = pressure / resistance

What is the relationship described by Ohm's law in terms of flow? a) Flow = pressure + resistance b) Flow = pressure × resistance c) Flow = pressure / resistance d) Flow = resistance / pressure

c) Flow = pressure / resistance

What simplification is made when deriving the equation for fractional flow reserve (FFR)? a) FFR = (pd - pv) / (pa - pv) b) FFR = (pd - pv) / Rmin c) FFR = pd / pa d) FFR = pa / pd

c) FFR = pd / pa

Under what condition is the resistance imposed by the normal myocardial bed minimal? a) During increased heart rate b) At rest c) Under maximum arteriolar vasodilation d) During systole

c) Under maximum arteriolar vasodilation

What does FFR represent in relation to normal maximum flow? a) The total flow possible in a stenosed vessel b) The fraction of normal maximum flow achievable in the presence of epicardial coronary stenosis c) The absolute maximum flow regardless of conditions d) The average flow in all coronary vessels

b) The fraction of normal maximum flow achievable in the presence of epicardial coronary stenosis

What are the two important assumptions for measuring and clinically using FFR? a) Maximal coronary flow and minimal heart rate b) Maximal hyperemia in the target vessel and negligible coronary venous pressure c) Normal aortic pressure and high myocardial contractility d) Constant resistance and elevated venous pressure

b) Maximal hyperemia in the target vessel and negligible coronary venous pressure

How is FFR typically measured in clinical practice? a) By assessing patient symptoms and blood pressure b) By simultaneously measuring mean aortic pressure and coronary pressure distal to a stenosis c) By using imaging techniques to visualize blood flow d) By evaluating the electrocardiogram (ECG) during exercise

b) By simultaneously measuring mean aortic pressure and coronary pressure distal to a stenosis

What physiological parameters is FFR independent of? a) Heart rate, systemic blood pressure, or myocardial contractility b) Patient age and weight c) Ventricular size and wall thickness d) Oxygen saturation and hemoglobin levels

a) Heart rate, systemic blood pressure, or myocardial contractility

What was the initial FFR threshold identified for identifying patients who would benefit from revascularization? a) 0.70 b) 0.75 c) 0.80 d) 0.85

b) 0.75

In the study by Pijls et al., how many patients had an FFR <0.75? a) 10 b) 21 c) 45 d) 1005

b) 21

What sensitivity and specificity were achieved using an FFR cutoff of 0.75 in the study? a) Sensitivity of 100%, specificity of 88% b) Sensitivity of 75%, specificity of 93% c) Sensitivity of 88%, specificity of 100% d) Sensitivity of 93%, specificity of 75%

c) Sensitivity of 88%, specificity of 100%

What FFR threshold was modified to and is currently used in clinical practice? a) 0.70 b) 0.75 c) 0.80 d) 0.85

c) 0.80

In the FAME study, how many patients were randomized to undergo PCI guided by angiography versus guided by FFR? a) 500 b) 888 c) 1005 d) 1500

c) 1005

What was the event rate at 1 year for the combined primary endpoint in the angiography group? a) 12.7% b) 13.2% c) 18.3% d) 20.5%

c) 18.3%

What was the hazard ratio for the primary outcome in the PCI plus optimal medical therapy group compared to the medical therapy group in FAME 2? a) 0.50 b) 0.32 c) 0.75 d) 0.95

b) 0.32

What was a significant driver of the event rate in the FAME 2 study? a) Deaths b) Nonfatal myocardial infarctions c) Urgent revascularization d) Repeat revascularization

c) Urgent revascularization

In what scenarios has FFR been shown to be useful? a) Only in single-vessel disease b) In left main lesions, nonculprit lesions in ACS, tandem lesions, and bifurcation lesions c) Exclusively in patients undergoing surgery d) In patients with a history of heart attacks only

b) In left main lesions, nonculprit lesions in ACS, tandem lesions, and bifurcation lesions

What does the instantaneous wave-free ratio (iFR) measure? a) The total blood flow in the coronary arteries b) The hemodynamic significance of a coronary artery stenosis c) The flow velocity during systole d) The heart rate during diastole

b) The hemodynamic significance of a coronary artery stenosis

When is iFR measured during the cardiac cycle? a) During early diastole b) During the wave-free period of mid to late diastole c) During systole d) Throughout the entire cardiac cycle

b) During the wave-free period of mid to late diastole

What physiological condition is present during the wave-free period when measuring iFR? a) The highest flow and lowest microcirculatory resistance b) The lowest pressure and highest resistance c) No flow and no pressure d) Constant heart rate and blood pressure

a) The highest flow and lowest microcirculatory resistance

How does pressure relate to flow velocity during the wave-free period? a) They are inversely related b) They are independent of each other c) They are linearly related d) Flow velocity is constant regardless of pressure

c) They are linearly related

What is a key difference between iFR and FFR assessment? a) iFR requires hyperemia and adenosine b) iFR is measured during systole c) iFR does not require hyperemia (and thus adenosine) d) iFR can only be performed in a hospital setting

c) iFR does not require hyperemia (and thus adenosine)

What is the primary benefit of using iFR over FFR in clinical practice? a) It provides more accurate measurements b) It eliminates the need for medication to induce hyperemia c) It is less invasive than FFR d) It can be performed on patients with severe atherosclerosis

b) It eliminates the need for medication to induce hyperemia

What were the names of the two large studies that compared FFR and iFR? a) FAME and FAME 2 b) DEFINE-FLAIR and iFR-SWEDEHEART c) ISCHEMIA and COURAGE d) ACRE and MASSAGE

b) DEFINE-FLAIR and iFR-SWEDEHEART

How many patients were enrolled in the DEFINE-FLAIR study? a) 2037 b) 2492 c) 1005 d) 1182

b) 2492

What was the primary endpoint in both studies? a) Rate of recurrent angina b) Rate of major adverse cardiac events at 6 months c) Rate of a composite of death from any cause, nonfatal MI, or unplanned revascularization within 12 months d) Rate of complications from PCI

c) Rate of a composite of death from any cause, nonfatal MI, or unplanned revascularization within 12 months

In the DEFINE-FLAIR study, how many patients in the iFR group experienced the primary endpoint? a) 68 of 1012 b) 83 of 1182 c) 78 of 1148 d) 61 of 1007

c) 78 of 1148

What was the result of the primary endpoint comparison between the iFR and FFR groups in the DEFINE-FLAIR study? a) iFR was significantly better b) FFR was significantly better c) No significant difference was found (P = 0.78) d) Both groups had equal event rates at 3 months

c) No significant difference was found (P = 0.78)

How many patients in the iFR-SWEDEHEART study experienced the primary endpoint in the iFR group? a) 61 of 1007 b) 68 of 1012 c) 83 of 1182 d) 78 of 1148

b) 68 of 1012

What was the conclusion of both studies regarding the iFR-guided revascularization strategy? a) It was superior to FFR-guided strategy b) It was noninferior to FFR-guided strategy concerning major adverse cardiac events at 12 months c) It had a higher rate of complications d) It was only beneficial in patients with stable angina

b) It was noninferior to FFR-guided strategy concerning major adverse cardiac events at 12 months

What was a significant finding regarding the rate of PCI performed in the studies? a) Higher in the FFR group b) Higher in the iFR group c) Lower in the iFR group d) No PCI was performed in either group

c) Lower in the iFR group

What technology is used to measure lesion-specific FFR from coronary CT angiography (CCTA)? a) MRI technology b) Computational fluid dynamics c) Echocardiography d) Positron emission tomography (PET)

b) Computational fluid dynamics

Which of the following is NOT one of the assumptions underlying CT-FFR? a) Coronary flow at rest is proportional to myocardial mass b) Resistance of the microcirculation at rest is inversely but not linearly proportional to vessel size c) The microcirculation reacts unpredictably to maximal hyperemia d) The microcirculation reacts predictably to maximal hyperemia in patients with normal coronary flow

c) The microcirculation reacts unpredictably to maximal hyperemia

What is one of the main limitations of CT-FFR mentioned in the text? a) It requires a longer hospital stay b) It is time-consuming and available only in select centers c) It uses high doses of radiation d) It is applicable to all patient populations without restrictions

b) It is time-consuming and available only in select centers

What must be considered negligible when deriving the equations for FFR and iFR? a) Arterial pressure b) Cardiac output c) Venous pressure and resistance d) Heart rate

c) Venous pressure and resistance

What is the relationship between FFR and clinical outcomes? a) It is defined by a fixed threshold value b) It is a continuous and independent relationship c) It only correlates with immediate outcomes d) It is inconsistent and varies by patient

b) It is a continuous and independent relationship

What limitation do FFR and iFR have regarding microvasculature function? a) They only measure microvasculature function in patients with acute coronary syndromes b) They provide detailed analysis of microvascular flow c) They do not measure microvasculature function, which can contribute to myocardial ischemia d) They require advanced imaging to assess microvasculature

c) They do not measure microvasculature function, which can contribute to myocardial ischemia