Clinical outcome of deferring angioplasty in patients with normal translesional pressure-flow velocity measurements

Heart Team risk assessment with angiography-derived fractional flow reserve determining the optimal revascularization strategy in patients with multivessel disease: Trial design and rationale for the DECISION QFR randomized trial

In patients with multivessel disease (MVD), functional information on lesions improves the prognostic capability of the SYNTAX score. Quantitative flow ratio (QFR®) is an angiography-derived fractional flow reserve (FFR) that does not require a pressure wire or pharmacological hyperemia. We aimed to investigate the feasibility of QFR-based patient information in Heart Teams' discussions to determine the optimal revascularization strategy for patients with MVD. We hypothesized that there is an acceptable agreement between treatment recommendations based on the QFR approach and recommendation based on the FFR approach. The DECISION QFR study is a prospective, multicenter, randomized controlled trial that will include patients with MVD who require revascularization. Two Heart Teams comprising cardiologists and cardiac surgeons will be randomized to select a revascularization strategy (percutaneous coronary intervention or coronary artery bypass graft) according to patient information either based on QFR or on FFR. All 260 patients will be assessed by both teams with reference to the anatomical and functional SYNTAX score/SYNTAX score II 2020 derived from the allocated physiological index (QFR or FFR). The primary endpoint of the trial is the level of agreement between the treatment recommendations of both teams, assessed using Cohen's κ. As of March 2022, the patient enrollment has been completed and 230 patients have been discussed in both Heart Teams. The current trial will indicate the usefulness of QFR, which enables a wireless multivessel physiological interrogation, in the discussions of Heart Teams to determine the optimal revascularization strategy for MVD.

Clinical Outcomes Data for Instantaneous Wave-Free Ratio-Guided Percutaneous Coronary Intervention

Instantaneous wave-free ratio (iFR) is a vasodilator-free index of coronary blood flow used for revascularization decision-making. iFR-based revascularization also had a decreased rate of adverse effects from vasodilators, shorter procedure times, and lower revascularization rates. iFR-pullback predicts post-percutaneous coronary intervention physiologic outcomes in tandem and diffuse coronary lesions. iFR may be particularly useful in patients with potential adenosine resistance, contraindications to adenosine, and multivessel or serial lesions. iFR is a useful tool both with and without fractional-flow reserve for revascularization planning.

Positron Emission Tomography-Determined Hyperemic Flow, Myocardial Flow Reserve, and Flow Gradient-Quo Vadis?

Positron emission tomography/computed tomography (PET/CT) applied with positron-emitting flow tracers such as ¹³N-ammonia and ⁸²Rubidium enables the quantification of both myocardial perfusion and myocardial blood flow (MBF) in milliliters per gram per minute for coronary artery disease (CAD) detection and characterization. The detection of a regional myocardial perfusion defect during vasomotor stress commonly identifies the culprit lesion or most severe epicardial narrowing, whereas adding regional hyperemic MBFs, myocardial flow reserve (MFR), and/or longitudinal flow decrease may also signify less severe but flow-limiting stenosis in multivessel CAD. The addition of regional hyperemic flow parameters, therefore, may afford a comprehensive identification and characterization of flow-limiting effects of multivessel CAD. The non-specific origin of decreases in hyperemic MBFs and MFR, however, prompts an evaluation and interpretation of regional flow in the appropriate context with the presence of obstructive CAD. Conversely, initial results of the assessment of a longitudinal hyperemic flow gradient suggest this novel flow parameter to be specifically related to increases in CAD caused epicardial resistance. The concurrent assessment of myocardial perfusion and several hyperemic flow parameters with PET/CT may indeed open novel avenues of precision medicine to guide coronary revascularization procedures that may potentially lead to a further improvement in cardiovascular outcomes in CAD patients.

Use of the Instantaneous Wave-free Ratio or Fractional Flow Reserve in PCI

BACKGROUND

Coronary revascularization guided by fractional flow reserve (FFR) is associated with better patient outcomes after the procedure than revascularization guided by angiography alone. It is unknown whether the instantaneous wave-free ratio (iFR), an alternative measure that does not require the administration of adenosine, will offer benefits similar to those of FFR.

METHODS

We randomly assigned 2492 patients with coronary artery disease, in a 1:1 ratio, to undergo either iFR-guided or FFR-guided coronary revascularization. The primary end point was the 1-year risk of major adverse cardiac events, which were a composite of death from any cause, nonfatal myocardial infarction, or unplanned revascularization. The trial was designed to show the noninferiority of iFR to FFR, with a margin of 3.4 percentage points for the difference in risk.

RESULTS

At 1 year, the primary end point had occurred in 78 of 1148 patients (6.8%) in the iFR group and in 83 of 1182 patients (7.0%) in the FFR group (difference in risk, -0.2 percentage points; 95% confidence interval [CI], -2.3 to 1.8; P<0.001 for noninferiority; hazard ratio, 0.95; 95% CI, 0.68 to 1.33; P=0.78). The risk of each component of the primary end point and of death from cardiovascular or noncardiovascular causes did not differ significantly between the groups. The number of patients who had adverse procedural symptoms and clinical signs was significantly lower in the iFR group than in the FFR group (39 patients [3.1%] vs. 385 patients [30.8%], P<0.001), and the median procedural time was significantly shorter (40.5 minutes vs. 45.0 minutes, P=0.001).

CONCLUSIONS

Coronary revascularization guided by iFR was noninferior to revascularization guided by FFR with respect to the risk of major adverse cardiac events at 1 year. The rate of adverse procedural signs and symptoms was lower and the procedural time was shorter with iFR than with FFR. (Funded by Philips Volcano; DEFINE-FLAIR ClinicalTrials.gov number, NCT02053038 .).

Myocardial blood flow: Putting it into clinical perspective

In recent years, positron emission tomography/computed tomography (PET/CT)-determined myocardial perfusion in conjunction with myocardial blood flow (MBF) quantification in mL·g(-1)·min(-1) has emerged from mere research application to initial clinical use in the detection and characterization of the coronary artery disease (CAD) process. The concurrent evaluation of MBF during vasomotor stress and at rest with the resulting myocardial flow reserve (MFR = MBF during stress/MBF at rest) expands the scope of conventional myocardial perfusion imaging not only to the detection of the most advanced and culprit CAD, as evidenced by the stress-related regional myocardial perfusion defect, but also to the less severe or intermediate stenosis in patients with multivessel CAD. Due to the non-specific nature of the hyperemic MBF and MFR, the interpretation of hyperemic flow increases with PET/CT necessitates an appropriate placement in the context with microvascular function, wall motion analysis, and eventually underlying coronary morphology in CAD patients. This review aims to provide a comprehensive overview of various diagnostic scenarios of PET/CT-determined myocardial perfusion and flow quantification in the detection and characterization of clinically manifest CAD.

Normal stress-only myocardial single photon emission computed tomography predicts good outcome in patients with coronary artery stenoses between 40 and 70

OBJECTIVE

Normal stress myocardial single photon emission computed tomography (SPECT) usually indicates good physiologic function of all coronary lesions, and also indicates a good outcome. We hypothesize that it can still predict good outcome in patients with coronary stenoses between 40 and 70%.

METHODS

A group of patients who underwent stress myocardial SPECT after coronary angiography were consecutively recruited in our center. Patients were eligible if they had one or more coronary stenoses between 40 and 70%. Patients with coronary stenoses greater than 50% diameter of left main or greater than 70% diameter of nonleft main epicardial vessels, and left ventricular ejection fraction less than 50% were excluded. The outcome was defined as major adverse events, including cardiac death, nonfatal myocardial infarction, and revascularization. Patients' survival curves were constructed accorded to the method of Kaplan and Meier and compared using the log-rank test.

RESULTS

A study cohort of 77 patients was enrolled. According to the summed stress score, 43 patients were assigned to the perfusion defect group and 34 patients were assigned to the perfusion normal group. The follow-up duration was 6.4±0.3 years. In the perfusion normal group, only one of 34 (2.9%) patients developed major adverse events. In the perfusion defect group, six of 43 (14%) developed major adverse events, P-value of 0.041.

CONCLUSION

It is safe to defer a percutaneous coronary intervention in patients with coronary stenoses between 40 and 70% and normal stress myocardial SPECT.

Coronary physiology assessment in the catheterization laboratory

Physicians cannot rely solely on the angiographic appearance of epicardial coronary artery stenosis when evaluating patients with myocardial ischemia. Instead, sound knowledge of coronary vascular physiology and of the methods currently available for its characterization can improve the diagnostic and prognostic accuracy of invasive assessment of the coronary circulation, and help improve clinical decision-making. In this article we summarize the current methods available for a thorough assessment of coronary physiology.

Revascularization vs. Medical Therapy in Stable Ischemic Heart Disease

The keynote COURAGE and BARI-2D trials changed the way the interventional community selects patients for revascularization. What we now consider appropriate, especially for percutaneous coronary intervention, has narrowed significantly in scope compared to previous practice a decade ago. Medical therapy has been shown to be both safe and effective as a primary treatment modality for patients with stable ischemic heart disease on the whole. However, it appears that patients with a heavy ischemic burden may benefit from revascularization, although investigation of this is ongoing. Evidence preliminarily supports this practice with coronary artery bypass grafting, and possibly in specific populations undergoing multivessel intervention with functional assessment of lesion severity during PCI.

Assessment of coronary blood flow in the cardiac catheterization laboratory

Coronary blood flow is tightly autoregulated but is subject to epicardial and microvascular obstruction, primarily owing to coronary atherosclerosis. Because coronary flow limitation underlies ischemic heart disease, an understanding of coronary physiology is paramount. Measurement of coronary blood flow, once relegated to the research laboratory is now easily performed in the cardiac catheterization laboratory. In particular, the measurement of fractional flow reserve has been extensively studied and is an important adjunct to clinical decision making. Measurement of coronary flow informs clinicians of prognosis, guides revascularization therapy, and forms the basis of ongoing research in treatment of complex myocardial disease processes. Newer methods of assessing coronary flow measurements are undergoing validation for clinical use and should further enhance our ability to assess the importance of coronary flow in clinical disease.

Usefulness of the fractional flow reserve derived by intracoronary pressure wire for evaluating angiographically intermediate lesions in acute coronary syndrome

INTRODUCTION AND OBJECTIVES

In contrast to findings in stable ischemic heart disease, in acute coronary syndrome (ACS), measurement of the fractional flow reserve (FFR) using an intracoronary pressure wire has not been shown to be useful for evaluating angiographically equivocal coronary lesions. The aim of this study was to analyze outcomes at 1 year in ACS patients with lesions that were classed as intermediate on coronary angiography and which were not nonrevascularized because of the FFR value determined by intracoronary pressure wire.

METHODS

The observational study involved a cohort of patients admitted for ACS who had intermediate lesions on coronary angiography that were not revascularized because the FFR was >0.75. Functional studies were not carried out if there was angiographic evidence of instability. All-cause mortality, non-fatal myocardial infarction, revascularization of the target lesion and readmission for cardiac causes in the first year of the study were recorded.

RESULTS

The study included 106 patients with 127 lesions that were not revascularized because the FFR was >0.75. Their mean age was 69.9+/-10 years, 92 (86.8%) had non-ST-elevation ACS, the mean angiographic stenosis was 40.5+/-7.8%, and the mean FFR was 0.88+/-0.06. There were no complications during the procedure. The follow-up rate at 1 year was 95.1%. Events observed at 1 year were: 2 deaths (total mortality 1.9%), 0 fatal acute myocardial infarctions, 1 (0.9%) target lesion revascularization and 5 (4.7%) readmissions for cardiac causes.

CONCLUSIONS

Once lesions with clear angiographic signs of instability are excluded, intracoronary pressure wire measurement could be useful in ACS patients for avoiding unnecessary revascularization of angiographically intermediate coronary lesions.

Current concepts of integrated coronary physiology in the catheterization laboratory

Over the last 15 years, the use of invasive coronary physiology in the catheterization laboratory has demonstrated favorable outcomes for decision making in patients with intermediate single-vessel stenoses, complex bifurcation and ostial branch stenoses, multivessel coronary artery disease, and left main stenoses. A recent large multicenter study (FAME [FFR versus Angiography for Multivessel Evaluation]) found that a physiologically-guided approach was superior to the standard angiographically-guided approach for percutaneous revascularization in patients with multivessel coronary artery disease. This review addresses selected pertinent concepts and studies supporting the integration of coronary physiology in the catheterization laboratory for optimal patient outcomes.

Long-term outcomes after an arterial switch operation for simple complete transposition of the great arteries

BACKGROUND AND OBJECTIVES

Although coronary artery obstruction, aortic insufficiency (AI), and pulmonary stenosis (PS) have been reported after arterial switch operation (ASO), limited long-term studies on ASO exist. Our study aimed to examine long-term outcomes after ASO for simple complete transposition of the great arteries (TGA).

SUBJECTS AND METHODS

All 108 patients with simple complete TGA who underwent ASO at Seoul National University Children's Hospital between 1987 and 2004 were enrolled. We retrospectively reviewed the patients' medical records and the results of various functional and imaging studies.

RESULTS

Among 108 cases of ASO for simple TGA, 96 have been followed-up through the present time (mean follow-up duration was 11.7+/-8.6 years: range= 4 to 23 years). The 20-year rates of freedom from significant AI, PS, and coronary obstruction were 78.6%, 67.8%, and 95.8%, respectively. AI showed a tendency to progress as follow-up time increased in 21.4% of the population studied (p=0.014); however, AS, PS, and PI showed no such progression. Late coronary artery occlusion was not associated with the initial coronary arterial pattern. Re-operations were done for 13 patients (13.5%) at an average of 8+/-4.3 years after ASO. The survival rate was 96%, while the re-operation-free was 90% at 10 years and 83% at 20 years. Most patients showed normal physical growth with good activity {98%; New York Heart Association (NYHA) class 1 activity} and normal development (96%).

CONCLUSION

Although most patients showed normal physical growth and development after successful ASO, meticulous long-term follow-up is necessary because of progressive AI and coronary complications.

The prognostic value of combined intracoronary pressure and blood flow velocity measurements after deferral of percutaneous coronary intervention

OBJECTIVES

We evaluated deferral of PCI of intermediate coronary lesions (IL) using fractional (FFR) and coronary flow reserve (CFR) hyperemic stenosis resistance index (HSR) in patients with a negative or nondiagnostic and noninvasive stress tests.

BACKGROUND

Outcome after deferral of PCI of IL with discordant results between FFR and CFR is unknown.

METHODS

PCI was deferred in 186 IL (mean diameter stenosis: 52%). Patients were divided according to the results of FFR and CFR in group A; FFR >or= 0.75 and CFR >or= 2.0 (n = 129), group B; FFR >or= 0.75 and CFR 2.0 (n = 28), group C; FFR 0.75 and CFR >or= 2.0 (n = 23) and group D; FFR 0.75 and CFR 2.0 (n = 6). Patients were followed for one year to document major adverse cardiac events (MACE).

RESULTS

Nineteen MACEs (0 deaths, 4 myocardial infarctions, 1 CABG, and 14 PCIs) occurred during a follow up of 323 +/- 88 days. MACE rate was lowest (4.7%) when FFR, CFR, and HSR were normal. A higher MACE rate was observed when concordant abnormal (group D) or discordant results between FFR and CFR (group B and C) were compared to concordant normal values (group A, 33.3% vs. 19.7% vs. 5.4%, P = 0.008). Multivariate regression analysis showed a higher predictive power for HSR than for FFR and CFR.

CONCLUSIONS

Abnormal FFR or abnormal CFR was documented in 31% of intermediate coronary lesions. Deferral of PCI in this group was associated with a high MACE rate, which underscores the rationale of combined pressure and flow measurements providing a stenosis resistance index that is better suited for clinical decision making in these lesions.

Coronary artery stenosis in asymptomatic child after arterial switch operation: detection by transthoracic colour-flow doppler echocardiography

Arterial switch operation (ASO) has become the definitive anatomical correction for transposition of great arteries (TGA). Left coronary artery (LCA) ostial stenosis was detected by transthoracic Doppler echocardiography (TTDE) as a flame like colour flow diastolic signal and coronary flow reserve (CFR) was low, 1.3. It was treated successfully by a drug-eluted stent. These findings could be diagnostic for coronary ostial stenosis.

CONCLUSION

Coronary artery stenosis can be detected with colour Doppler echocardiography. Assessment of CFR provides information of the physiological significance of the coronary stenosis.

Prognostic value of coronary flow reserve in medically treated patients with left anterior descending coronary disease with stenosis 51% to 75% in diameter

According to American College of Cardiology/American Heart Association/Society for Cardiovascular Angiography and Interventions 2005 guidelines on percutaneous intervention, intracoronary physiologic measurement in the assessment of effects of intermediate coronary stenoses in patients with anginal symptoms is a class IIa indication. This study assessed the additional prognostic value of Doppler echocardiographically derived coronary flow reserve (CFR) in patients with single-vessel disease and intermediate stenosis severity. We enrolled 86 patients (44 men; 66 +/- 10 years of age) with angiographically assessed single-vessel coronary artery disease of the left anterior descending coronary artery (LAD) with quantitatively assessed diameter stenosis severity 50% to 75%. All patients underwent dipyridamole (up to 0.84 mg/kg over 6 minutes) stress echocardiography with wall motion analysis by 2-dimensional echocardiography and CFR evaluation of the affected artery by Doppler. All patients were followed up for a median of 14 months (first quartile 10, third quartile 18) after diagnostic coronary angiography (without percutaneous intervention for a clinically driven decision). Mean diameter stenosis of the LAD was 58 +/- 10%. Mean CFR of the LAD was 2.09 +/- 0.5. Regional wall motion abnormality at peak stress was present in 17 patients. During follow-up, 24 events occurred: 6 nonfatal ST-elevation myocardial infarctions and 18 non-ST-elevation myocardial infarctions. Thirty-month spontaneous event-free survival was higher in patients with normal CFR and lower in patients with decreased CFR (86% vs 30%, p = 0.0001). At Cox analysis, a CFR <2 (hazard ratio 24.2, 95% confidence interval 3.2 to 179.7, p = 0.002) was the only independent prognostic predictor of outcome. In conclusion, in medically treated patients with single-vessel disease of intermediate severity, decreased CFR is associated with a worse outcome.

Five-year follow-up in patients after therapy stratification based on intracoronary pressure measurement

BACKGROUND

Invasive coronary angiography (ICA) alone fails to accurately select patients with intermediate stenoses who should be treated by percutaneous coronary intervention (PCI). Previous studies have demonstrated the usefulness of fractional flow reserve (FFR) for identifying patients in whom deferring an intended PCI would be more beneficial than performing the planned procedure. The long-term safety of FFR-based therapy stratification, however, remains unknown. Therefore, the aim of this study was to retrospectively evaluate the long-term safety of an FFR-based therapy stratification in patients with intermediate coronary lesions detected by ICA.

METHODS

We included 56 patients presenting with a 50% to 75% angiographic stenosis by visual assessment on ICA, with negative, inconclusive, or no stress test, and in whom the intended PCI was deferred based on the result of the FFR measurement (ie, FFR > or = 0.75). The occurrence of major adverse cardiac events during a 5-year follow-up period was recorded.

RESULTS

A complete 5-year follow-up was available in all patients. Mean follow-up was 1868 +/- 380 days. During follow-up, 16 events (1 cardiac death, 4 noncardiac deaths, 11 revascularization procedures) occurred. The combined rate of cardiac death and nonfatal myocardial infarction was 1.8% over 5 years. Nine PCI procedures (5 target vessel, 4 nontarget vessel) were performed during follow-up based on objective signs of ischemia. The angina status was not different between inclusion and the 5-year follow-up.

CONCLUSION

Deferring PCI in patients without critical reduction in FFR may be a safe option during long-term follow-up.

Assessment of intermediate severity coronary lesions in the catheterization laboratory

The management of intermediate coronary lesions, defined by a diameter stenosis of 40% to 70%, continues to be a therapeutic dilemma for cardiologists. The 2-dimensional representation of the arterial lesion provided by angiography is limited in distinguishing intermediate lesions that require stenting from those that simply need appropriate medical therapy. In the era of drug-eluting stents, some might propose that stenting all intermediate coronary lesions is an appropriate solution. However, the possibility of procedural complications such as coronary dissection, no reflow phenomenon, in-stent restenosis, and stent thrombosis requires accurate stratification of patients with intermediate coronary lesions to appropriate therapy. Intravascular ultrasound (IVUS) and fractional flow reserve index (FFR) provide anatomic and functional information that can be used in the catheterization laboratory to designate patients to the most appropriate therapy. The purpose of this review is to discuss the critical information obtained from IVUS and FFR in guiding treatment of patients with intermediate coronary lesions. In addition, the importance of IVUS and FFR in the management of patients with serial stenosis, bifurcation lesions, left main disease, saphenous vein graft disease, and acute coronary syndrome will be discussed.

Physiological assessment of coronary artery disease in the cardiac catheterization laboratory: a scientific statement from the American Heart Association Committee on Diagnostic and Interventional Cardiac Catheterization, Council on Clinical Cardiology

With advances in technology, the physiological assessment of coronary artery disease in patients in the catheterization laboratory has become increasingly important in both clinical and research applications, but this assessment has evolved without standard nomenclature or techniques of data acquisition and measurement. Some questions regarding the interpretation, application, and outcome related to the results also remain unanswered. Accordingly, this consensus statement was designed to provide the background and evidence about physiological measurements and to describe standard methods for data acquisition and interpretation. The most common uses and support data from numerous clinical studies for the physiological assessment of coronary artery disease in the cardiac catheterization laboratory are reviewed. The goal of this statement is to provide a logical approach to the use of coronary physiological measurements in the catheterization lab to assist both clinicians and investigators in improving patient care.

Coronary Angiography, Lesion Classification and Severity Assessment

A joint task force of the American College of Cardiology and the American Heart Association established criteria in 1988 to estimate procedural success and complication rates after balloon angioplasty, based on the presence or absence of specific lesion characteristics. Advances in the technique of coronary intervention over the years have changed the management of patients who have coronary artery disease, resulting in safer and more effective percutaneous revascularization in patients previously deemed at high risk for nonsurgical approaches. Coronary angiography (visual or quantitative) is a simple,easy, and mostly reliable tool in the assessment of lesion severity, but it may be inconclusive in the borderline lesions (40% to 60% diameter obstruction). Anatomical (using intravascular ultrasound) and physiological (using coronary flow reserve or fractional flow reserve) lesion assessment may be required for adequate lesion evaluation, before and after percutaneous coronary intervention.

Performing versus deferring coronary angioplasty based on functional evaluation of vessel stenosis by pressure measurements: a clinical outcome study

AIM

The present study aimed to prospectively evaluate whether application of the concept of fractional flow reserve (FFR) guides the immediate decision to perform or to defer coronary angioplasty in unselected consecutive patients with one or more angiographically intermediate (50-70%) stenoses and non-conclusive or lacking non-invasive testing.

METHODS

We studied 112 patients (81 males and 31 females, aged 31-81 years) including 71 multivessel disease patients (63%) and 30 patients (27%) with unstable symptoms. FFR was measured with the use of a pressure-wire after adenosine-induced hyperaemia and compared with quantitative coronary angiography in 171 stenoses. Coronary angioplasty was performed in the presence of an FFR < 0.75 and deferred if FFR was > or = 0.75. Cardiac events including death, myocardial infarction, recurrent angina or symptoms requiring repeated hospitalization and target vessel revascularization (TVR) were recorded during a median period of 34 months (interquartile range 9-54 months).

RESULTS

Coronary angioplasty was deferred based on FFR results in 54 patients (group I). In the remaining 58 patients, angioplasty was performed in one or more stenoses that were significant by FFR and deferred in non-significant stenoses (group II). Overall, coronary angioplasty was performed in 71 vessels (41%) and deferred in 100 (59%). Cumulative cardiac events occurred in 12.9% of group I patients and in 24.1% of group II patients (chi-squared = 1.57, P = 0.20). TVR was required in 5% of the stenoses untreated based on FFR result in both groups and in 12.6% of stenoses that underwent coronary angioplasty (chi-squared = 3.25, P = 0.07; relative risk = 2.5, 95% confidence interval = 0.88-8.61).

CONCLUSIONS

In patients with angiographically intermediate stenoses, functional evaluation by FFR to select lesions that do not need to be treated invasively is safe. Unnecessary angioplasty and stenting may be saved in more than one half of individual coronary stenoses. The risk of major cardiac events and TVR of functionally non-significant stenoses is lower than the risk associated with coronary angioplasty. Our observations further support the use of pressure wire for physiological assessment of coronary artery stenosis in the catheterization room.

Physiologic assessment of jailed side branch lesions using fractional flow reserve

OBJECTIVES

This study was performed to evaluate the feasibility of the physiologic assessment of jailed side branches using fractional flow reserve (FFR) and to compare the measured FFR with the stenosis severity assessed by quantitative coronary angiography (QCA).

BACKGROUND

It is not well-known which side branches should be treated after stent implantation at main branches and how to assess the functional significance of these lesions.

METHODS

Ninety-seven jailed side branch lesions (vessel size > 2.0 mm, percent stenosis > 50% by visual estimation) after stent implantation at main branches were consecutively enrolled. The FFR was measured using a pressure wire at 5 mm distal and proximal to the ostial lesion of the jailed side branch.

RESULTS

The FFR measurement was successful in 94 lesions. Mean FFRs were 0.94 +/- 0.04 and 0.85 +/- 0.11 at the main branches and jailed side branches, respectively. There was a negative correlation between the percent stenosis and FFR (r = -0.41, p < 0.001). However, no lesion with < 75% stenosis had FFR < 0.75. Among 73 lesions with > or = 75% stenosis, only 20 lesions were functionally significant.

CONCLUSIONS

The FFR measurement in jailed side branch lesions is both safe and feasible. Quantitative coronary angiography is unreliable in the assessment of the functional severity of jailed side branch lesions, and measurement of FFR suggests that most of these lesions do not have functional significance.

One-year outcome of patients submitted to routine fractional flow reserve assessment to determine the need for angioplasty

AIMS

In patients submitted to coronary angiography, fractional flow reserve (FFR) assessment by a pressure wire can be used to guide the decision for revascularization. Routine application of FFR assessment and 1-year outcome of patients are poorly documented. The aim of this study was to report a 4-year single-centre experience where the use of FFR for decision making in equivocal lesions is encouraged.

METHODS AND RESULTS

A prospective registry was designed to collect clinical and angiographic characteristics, as well as 1-year clinical follow-up for all patients submitted to FFR assessment. The decisional cut-off point for revascularization was 0.80. Over a 4-year period, out of 6415 coronary angiographies, FFR was measured in 407 (6.3%) patients (469 lesions). FFR was assessed through 4 or 5 Fr diagnostic catheters in 330 (81%). Median FFR value was 0.87 (0.80; 0.93). On the basis of FFR results, 271 (67%) patients were treated with medical therapy alone. A subset of 71 (17%) patients were not treated in accordance with the results of FFR. All patients but four (i.e. 99%) had 1-year clinical follow-up. Three hundred and forty four (85%) were free from clinical event, six (1.5%) patients died, five (4%) had an acute coronary syndrome, and 20 (5%) underwent target-vessel revascularization. Event-free survival was comparable in patients with vs. without revascularization (0.94 +/- 0.02 and 0.93 +/- 0.01, respectively). Patients had significantly better 1-year outcome when treated in accordance with the results of the FFR assessment.

CONCLUSION

In routine practice, FFR assessment during diagnostic angiography was performed in 6.3%. On the basis of FFR, two-thirds of patients with 'intermediate' lesions were left unrevascularized, with a favourable outcome, when FFR was above 0.80. These data suggest that routine use of FFR during diagnostic catheterization is feasible, safe, and provide help to guide decision making.

Optimizing revascularization strategies in patients with multivessel coronary disease: Impact of intracoronary pressure measurements

OBJECTIVES

In patients with multivessel coronary disease, the functional significance of each lesion is often unclear, and preinterventional stress tests may be inconclusive. In this setting, intracoronary pressure measurements may be helpful to define the optimal revascularization strategy.

METHODS

Twenty-five consecutive patients (aged 64 +/- 11 years) with multivessel disease, inconclusive stress tests or not performed stress tests, and an angiographically intermediate coronary artery stenosis in at least 1 major vessel underwent intracoronary pressure measurements. Myocardial fractional flow reserve was measured for the intermediate lesions under the condition of maximum hyperemia induced by intravenous adenosine (140 microg x kg(-1) x min(-1). Revascularization strategies based on angiographic information alone were compared with treatment strategies based on fractional flow reserve results.

RESULTS

The original recommendation of the revascularization procedure of choice (bypass operation or angioplasty) was changed in 9 patients (36%) on the basis of the results of fractional flow reserve measurements. In 6 more patients, pressure measurements led to a change in the recommended number of anastomoses to be aimed for during the operation. Within diffusely diseased vessels, fractional flow reserve provided an exact segmental resolution of pathologic vessel resistance for optimal graft placement. Significant left main disease was confirmed in 3 of 6 patients and was detected in 3 angiographically unsuspected cases.

CONCLUSIONS

In patients with multivessel disease, coronary pressure-derived fractional flow reserve is a valuable tool to guide clinical decision making and support cardiologists and cardiovascular surgeons in the composition of optimal revascularization strategies.

Usefulness of fractional flow reserve in determining the indication of target lesion revascularization

The objective of this study was to examine the usefulness of fractional flow reserve (FFR) in determining the indication of target lesion revascularization (TLR) at follow-up angiography after percutaneous coronary intervention (PCI). One hundred forty-seven patients with 155 lesions that had intermediate restenosis took part in this study. FFR was measured in all patients for the evaluation of stenosis severity. Then TLR was performed when FFR was < 0.75, and TLR was deferred when FFR was > or = 0.75. Patients in whom TLR was deferred were followed up clinically (25 +/- 11 months). In 98 patients (67%) who underwent stress myocardial scintigraphy before angiography, the results of the scintigraphy were compared with FFR results. TLR was performed in 34 lesions (22%). After TLR, the Canadian Cardiovascular Society class decreased significantly (from 1.5 +/- 0.7 to 1.1 +/- 0.5; P < 0.05). In 113 patients who did not undergo TLR, only 4 patients (3.5%) had cardiac events (re-PCI in 1 patient and a positive SPECT in 3 patients). Discordance between the results of scintigraphy and FFR was observed in 30 patients (30%), but the patients who had good values of FFR > or = 0.75 showed a nil event rate (0%). FFR might be useful for the determination of the indication of TLR.

Intracoronary Continuous Adenosine Infusion A Novel and Effective Way of Inducing Maximal Hyperemia for Fractional Flow Reserve Measurement

BACKGROUND

Various methods are used to induce maximal hyperemia for physiologic studies, but the feasibility and efficacy of continuous intracoronary (IC) infusion of adenosine for measurement of fractional flow reserve (FFR) has not been well-defined.

METHODS AND RESULTS

Patients with intermediate coronary artery stenosis were consecutively enrolled. In the phase I study, FFR was measured after 3 dosages of IC adenosine infusion (180, 240 and 300 microg/min) in 30 patients. The phase II study was performed to compare the hyperemic efficacy of IC infusion (240 microg/min) with IC bolus injection (40, 80 microg) and intravenous (IV) infusion (140 microg x kg (-1) x min(-1)) of adenosine in 20 patients. In the phase I study, no significant differences in FFR were observed with the 3 different doses of IC infusion (p = 0.06). In the phase II study, FFR after an IC bolus injection (0.83+/-0.06) was significantly higher than with IV (0.79+/-0.07) or IC (0.78+/-0.09) infusion (p < 0.01). However, no difference in FFR was observed for IC and IV infusions.

CONCLUSION

IC infusion of adenosine seems to be a safe and effective method of inducing maximal hyperemia for FFR measurement.

Recovery of impaired microvascular function in collateral dependent myocardium after recanalisation of a chronic total coronary occlusion

OBJECTIVE

To assess the potential for recovery of impaired microvascular function in collateral dependent myocardium after recanalisation of a chronic total coronary occlusion and the determinants of this recovery.

PATIENTS AND DESIGN

120 patients underwent a successful recanalisation of a chronic total coronary occlusion (duration > 2 weeks) and a follow up angiography after a mean (SD) of 5.0 (1.2) months. The coronary flow velocity reserve (CFVR) and the fractional flow reserve were measured after recanalisation and at follow up. Global and regional left ventricular (LV) function were analysed by quantitative angiography.

RESULTS

Microvascular dysfunction, defined by a CFVR < 2.0 and a fractional flow reserve > or = 0.75, was observed in 55 (46%) patients after recanalisation. Microvascular function improved during follow up in 24 (20%). The CFVR increased during follow up from 2.01 (0.58) to 2.50 (0.79) (p < 0.001), due to a decrease in basal average peak velocity from 30.7 (14.9) cm/s to 25.5 (13.3) cm/s (p = 0.001). Improved microvascular function was associated with an improved regional LV function, shown by a correlation between increased wall motion severity index and increased CFVR (r = 0.38, p = 0.003). The major determinant of microvascular dysfunction at baseline was the presence of diabetes mellitus (odds ratio 4.3, 95% confidence interval 1.8 to 10.2), which remained so at follow up (odds ratio 4.1, 95% confidence interval 1.3 to 13.4). Improvement of LV function was not impaired by the presence of microvascular dysfunction after recanalisation.

CONCLUSIONS

The frequently observed microvascular dysfunction after recanalisation of a chronic total coronary occlusion is a transient phenomenon in most patients and is influenced by the presence of diabetes mellitus. It does not impede the recovery of LV function. Improved regional LV function is associated with improved microvascular function.

Mortality in patients with microvascular disease

Patients with chest pain/ischemic cardiac disease and normal coronary arteriography are thought to have a benign prognosis despite diminished quality of life. Many patients with hypertension fall into this group, at least in the early stage of their disease. Whether abnormalities in coronary flow reserve in these patients are associated with increased morbidity and mortality is unknown. One hundred sixty-eight patients with chest pain/ischemic cardiac disease and normal coronary angiograms who underwent invasive measures of coronary flow reserve were followed longitudinally. Mortality and quality of life were ascertained by query of the national death index and telephone administration of standardized questionnaires. Patient follow-up occurred at a mean of 8.5 years. In the abnormal coronary flow reserve group, 12 deaths (20%) were documented in 60 patients compared with eight out of 108 patients (7%; p=0.016) with normal coronary flow reserve. Coronary flow reserve did not predict impairment in functional health status in long-term follow-up. Thus, invasive measures of coronary flow reserve in patients with chest pain/ischemic cardiac disease and normal coronary angiograms predicted increased mortality. Surviving patients with chest pain/ischemic cardiac disease and normal coronary angiograms have significant morbidity.

Impaired left ventricular function after arterial switch operation: exclusion of significant coronary artery stenosis with an intravascular Doppler guidewire

Patients after arterial switch operation for transposition of the great arteries are at risk for coronary artery stenosis or obstruction due to intraoperative manipulation. This case describes an infant with impaired left ventricular function 8 months after arterial switch operation. A hemodynamically significant left coronary artery stenosis was excluded by determination of coronary flow reserve using an intravascular Doppler guidewire.

Assessment of intermediate stenosis in the left anterior descending coronary artery with contrast-enhanced transthoracic Doppler echocardiography

BACKGROUND

Visual or quantitative assessment of coronary angiography may not exactly predict the physiological significance of intermediate (40-70%) coronary stenosis. Coronary flow reserve is a well-established marker of the functional significance of coronary stenosis.

OBJECTIVES

The aim of this study was to compare the coronary flow velocity reserve (CFVR) using contrast-enhanced transthoracic Doppler echocardiography (CE-TTDE) with thallium-201 imaging in assessment of intermediate lesions in the left anterior descending coronary artery (LAD).

METHODS

A consecutive series of 50 patients with intermediate stenosis in the LAD underwent pharmacological stress thallium-201 imaging and CFVR measured by CE-TTDE.

RESULTS

CFVR could be measured in 49 of 50 patients by the present method. A CFVR <2.0 predicted the presence of a stress thallium defect in 12 of 14 patients (agreement=90%, kappa=0.76, P < 0.001). The sensitivity and specificity of CFVR for stress thallium-201 results were 86 and 91%, respectively. In contrast, significant stenosis (>50% by diameter) showed fair agreement for stress thallium defects (agreement=59%, kappa=0.28, P < 0.05).

CONCLUSIONS

In the evaluation of intermediate lesions in the LAD, CFVR as assessed by CE-TTDE could accurately predict the presence of ischemia on stress thallium imaging, whereas angiographic stenosis did not yield reliable results.

[Late recovery of coronary flow reserve in patients successfully treated with a percutaneous procedure]

INTRODUCTION AND OBJECTIVES

Coronary angiograms are of limited value for the assessment of the results of percutaneous interventions. Intracoronary Doppler studies have been used to overcome these difficulties. The achievement of a coronary flow reserve (CFR) > 2-2.5 after the procedure is considered a good result and further optimization is generally not required. However, coronary flow reserve may not recover immediately, despite optimal procedural results. The aim of this study is to assess the temporal course of the recovery of coronary flow reserve after successful revascularization.

PATIENTS AND METHOD

We studied 34 patients with coronary heart disease who were successfully treated by balloon angioplasty (n = 8) or stent implantation (n = 26). In all patients, serial observations were made by quantitative angiography and intracoronary Doppler (0.014 = flow-wire). Patients were studied: a) before treatment; b) immediately after, and c) 8 3 months later.

RESULTS

The baseline coronary flow reserve was 1.3 0.4 and increased to 2.4 0.8 after the procedure (p < 0.01). At 8 months follow-up there was a significant increase (3 0.8; p < 0.01). This late improvement in coronary flow reserve was associated with a decline in average peak velocity at follow-up. Patients with impaired CFR immediately after treatment had a greater increase in CFR during followup than those with CFR > 2 after treatment (1.4 0.9 vs 0.4 0.6; p < 0.01).

CONCLUSIONS

After a successful coronary intervention, CFR increases immediately, but some patients may experience additional improvement during follow-up. This increase was greater in patients who showed less improvement in coronary flow reserve immediately after treatment. Our findings suggest that the use of Doppler parameters in the immediate assessment of percutaneous coronary intervention results have limitations.

Measuring pressure-derived fractional flow reserve through four French diagnostic catheters

Measurement of fractional flow reserve (FFR) with a pressure wire is used to discriminate between patients with and without functionally significant lesions. FFR can be assessed through a conventional 4Fr diagnostic catheter, which is a more convenient method of assessment. The aim of this study was to assess the feasibility, safety, repeatability, and reliability of routine FFR measurements through 4Fr diagnostic catheters. From a single-center prospective registry, results of FFR assessment through a 4Fr catheter were used to determine: (1) feasibility and safety, by the procedural success rate and immediate and 30-day clinical outcome; (2) repeatability, by the intraclass correlation coefficient and comparison of the difference (means +/- 2 SDs); and (3) reliability, by comparison of results obtained using 4Fr versus 7Fr guiding catheters. During the study period, FFR was measured in 190 patients, in 122 using a diagnostic 4Fr catheter (study population) and in 68 using a 7Fr guiding catheter. Measurement of FFR wa successful in 115 of 122 patients (94%). No complications related to the use of the 4Fr catheter occurred. Repeatability was determined from 108 repeated measurements: the intraclass correlation coefficient was 0.942 and the mean difference between repeated FFR measurements was -0.001 +/- 0.038. Reliability was determined from 15 unselected patients; there was no systematic error and only 1 value was out of the range of 2 SDs of the mean difference. Using a threshold value of 0.75, the Kappa coefficient for the qualitative agreement was 0.84. Thus, pressure-derived FFR assessment can safely be performed through 4Fr diagnostic catheters, with similar repeatability and reliability as 7Fr guiding catheters, resulting in a simplification of the measurement procedure.

Deferring angioplasty in intermediate coronary lesions based on coronary flow criteria is safe: comparison of a deferred group to an intervention group

The decision for revascularization in patients with intermediate coronary lesions remains a challenging topic, particularly when objective data of reversible ischemia are lacking. In some of the patients, coronary revascularization is performed or deferred without definitive evidence on the clinical significance of the coronary stenosis. We investigated the usefulness of coronary flow reserve (CFR) measurements in 28 patients with intermediate coronary lesions. We compared 20 patients who underwent angioplasty based on Doppler-wire-derived CFR with 8 patients for whom angioplasty was deferred (diameter stenosis of 50.7 +/- 2.0% versus 46.5 +/- 3.1%, P < 0.0001 and CFR of 1.80 +/- 0.32 versus 2.65 +/- 0.11, P = 0.002, respectively). Angioplasty resulted in normalization of the CFR to 2.57 +/- 0.53 (P < 0.0001, versus the baseline value). During a follow-up period of 58.1 weeks (range 23-149 weeks), eight patients in the revascularization group were readmitted to the hospital, one of them with a myocardial infarction in the territory of the target vessel, compared with only one admission in the deferred group. Target-vessel revascularization was performed in three patients (a fourth patient declined it) in the former group, compared with only one in the latter. Symptomatic improvement or no change in clinical status was observed in the majority of patients in both groups (90% in the revascularization group and 87.5% in the deferred group). We conclude that in a selected group of patients with intermediate coronary lesions, measurement of CFR may be a useful tool in determining the need for revascularization based on its physiologic significance. Importantly, deferring PTCA in patients with intermediate lesions and normal CFR values seems to be safe.

New balloon-thermography catheter for in vivo temperature measurements in human coronary atherosclerotic plaques: a novel approach for thermography?

Although ex vivo studies showed marked thermal heterogeneity in atheromatic plaques, in in vivo human studies trivial temperature variations are recorded due to the cooling effect of blood flow. We investigated a new balloon-thermogaphy catheter for temperature measurements during coronary flow interruption. A thermistor probe is positioned at the distal segment of the catheter. At the opposite site of the thermistor, a balloon is placed. By inflation of the balloon, coronary flow is interrupted. Ten patients with effort angina were studied. Coronary flow velocity was continuously recorded. Temperature was recorded at the proximal vessel wall and at the lesion before, during, and after complete interruption of blood flow by inflation of the balloon. DeltaTp was assigned as the difference between the background temperature and the maximal temperature during and after balloon inflation. DeltaTl was assigned as the difference between the atherosclerotic plaque and the proximal vessel wall. The procedure was not complicated. DeltaTp during and after balloon inflation was 0.01 +/- 0.01 degrees C and -0.003 +/- -0.01 degrees C (P < 0.001), respectively. DeltaTl was 0.07 +/- 0.04 degrees C at baseline, 0.17 +/- 0.06 degrees C (59.3% +/- 11.8% increase) during, and 0.07 +/- 0.05 degrees C after flow interruption (P < 0.001). DeltaTl was greater than DeltaTp during and after impairment of flow (P < 0.001). In vivo atherosclerotic plaque temperature recording seems to be feasible with this new balloon-thermography catheter. This device may introduce a new approach for the detection of thermal heterogeneity in plaques by addressing the issue of cooling effect of blood flow.

Thermal heterogeneity in stable human coronary atherosclerotic plaques is underestimated in vivo: the "cooling effect" of blood flow

OBJECTIVES

This study investigated whether temperature measurements are influenced by blood flow.

BACKGROUND

Previous ex vivo studies showed marked thermal heterogeneity in atheromatic plaques. In stable lesions, however, trivial in vivo temperature variations are recorded, perhaps due to the "cooling effect" of blood flow.

METHODS

Eighteen patients with effort angina were studied. Coronary flow velocity was continuously recorded; over another guidewire, temperature measurements were performed at the proximal vessel wall and at the lesion before, during, and after complete interruption of blood flow by inflation of a balloon. The DeltaTp was assigned as the difference between the proximal vessel wall temperature and the maximal temperature during and after balloon inflation. The DeltaTl was assigned as the difference between the atherosclerotic plaque and the proximal vessel wall.

RESULTS

The procedure was not complicated. During and after complete interruption of flow, DeltaTp was 0.012 +/- 0.01 degrees C and -0.006 +/- -0.01 degrees C (p < 0.001), respectively. The DeltaTl was 0.08 +/- 0.04 degrees C at baseline and went to 0.18 +/- 0.05 degrees C (60.5 +/- 14.1% increase) during and 0.08 +/- 0.04 degrees C after flow interruption (p < 0.001). The DeltaTl was greater than DeltaTp during and after impairment of flow (p < 0.001). A correlation between the baseline average peak velocity and DeltaTl during flow interruption was found (R = 0.57, p = 0.01). In seven patients thermal heterogeneity was not detected at baseline, and during balloon inflation DeltaTl increased by 76.0 +/- 8.4%.

CONCLUSIONS

Thermal heterogeneity is underestimated in atherosclerotic plaques in patients with effort angina. Potential in vivo underestimation of heat production locally in human atherosclerotic is due to the "cooling effect" of coronary blood flow.

Evaluación y guía terapéutica de las lesiones coronarias intermedias en el laboratorio de hemodinámica

Contrast angiography has been used for nearly five decades to evaluate the severity of coronary lesions. However, when attempting to distinguish between intermediate coronary lesions able or unable to produce ischemia, the technique has several limitations. A large number of patients undergo cardiac catheterization without prior evaluation of coronary perfusion by non-invasive tests. This number is likely to increase in the coming years, because current recommendations favor the invasive treatment of acute coronary syndromes. This has triggered marked interest in new diagnostic techniques capable of assessing the physiological significance of intermediate lesions in the catheterization room. This paper reviews the different techniques currently available for scientifically assessing the significance of such lesions. The advantages and limitations of each are discussed.

Prognostic value of coronary blood flow velocity and myocardial perfusion in intermediate coronary narrowings and multivessel disease

OBJECTIVES

This study aimed to investigate the roles of intracoronary derived coronary flow velocity reserve (CFVR) and myocardial perfusion scintigraphy (single photon emission computed tomography, or SPECT) for management of an intermediate lesion in patients with multivessel coronary artery disease.

BACKGROUND

Evaluation of the functional significance of intermediate coronary narrowings (40% to 70% diameter stenosis) is important for clinical decision making and risk stratification.

METHODS

In a prospective, multicenter study, SPECT was performed in 191 patients with stable angina and multivessel disease and scheduled for angioplasty (percutaneous transluminal coronary angioplasty, or PTCA) of a severe coronary narrowing. Coronary flow velocity reserve was determined selectively distal to an intermediate lesion in another artery using a Doppler guidewire. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred when SPECT was negative or CFVR greater-than-or-equal 2.0. Patients were followed for one year to document major cardiac events (death, infarction, revascularization), related to the intermediate lesion.

RESULTS

Reversible perfusion defects were documented in the area of the intermediate lesion in 30 (16%) patients; CFVR was positive in 46 (24%) patients. Percutaneous transluminal coronary angioplasty of the intermediate lesion was deferred in 182 patients. During follow-up, 19 events occurred (3 myocardial infarctions, 16 revascularizations). Coronary flow velocity reserve was a more accurate predictor of cardiac events than was SPECT; relative risk: CFVR 3.9 (1.7 to 9.1), p < 0.05; SPECT 0.5 (0.1 to 3.2), p = NS. Multivariate analysis revealed CFVR as the only significant predictor for cardiac events.

CONCLUSIONS

Deferral of PTCA of intermediate lesions in multivessel disease is safe when CFVR greater-than-or-equal 2.0 (event rate 6%). This selective evaluation of coronary lesion severity during cardiac catheterization allows a more accurate risk stratification than does SPECT, which is important for clinical decision making in this patient cohort.