A Test in Context: Fractional Flow Reserve: Accuracy, Prognostic Implications, and Limitations

Comparison among various physiology and angiography-guided strategies for deferring percutaneous coronary intervention: A network meta-analysis

BACKGROUND/PURPOSE

It is unclear whether coronary physiology or coronary angiography (CA)-guided strategy is the more preferable approach for deferring percutaneous coronary intervention (PCI). We sought to evaluate the clinical efficacy of various PCI strategies through a network meta-analysis of randomized controlled trials (RCTs).

METHODS/MATERIALS

We searched multiple databases for RCTs investigating the impact of the following strategies for the purpose of determining whether or not to defer PCI: fractional flow reserve, instantaneous wave-free ratio, quantitative flow ratio (QFR), and CA. We conducted a network meta-analysis for trial-defined major adverse cardiovascular events (MACE), all-cause death, cardiovascular death, myocardial infarction (MI), target lesion revascularization (TLR), and stent thrombosis. We performed a subgroup analysis for those with acute coronary syndrome (ACS).

RESULTS

Our search identified 12 eligible RCTs including a total of 13,177 patients. QFR-guided PCI was associated with reduced MACE, MI, and TLR compared with CA-guided PCI (relative risk (RR) 0.68; 95 % confidence interval (CI] [0.49 to 0.94], RR 0.58; 95 % CI [0.36 to 0.96], and RR 0.58; 95 % CI [0.38 to 0.91], respectively). There were no significant differences in any pairs for all-cause death, cardiovascular death, or stent thrombosis. QFR was ranked the best in most outcomes. In the subgroup analysis of the ACS cohort, there were no significant differences in MACE between any comparisons.

CONCLUSIONS

QFR was associated with reduced MACE, MI, and TLR compared with CA, and ranked the best in most outcomes. However, this was not applied in the ACS cohort.

Comprehensive assessment of molecular function, tissue characterization, and hemodynamic performance by non-invasive hybrid imaging: Potential role of cardiac PETMR

Noninvasive cardiovascular imaging plays a key role in diagnosis and patient management including monitoring treatment efficacy. The usefulness of noninvasive cardiovascular imaging has been extensively studied and shown to have high diagnostic reliability and prognostic significance, while the nondiagnostic results frequently encountered with single imaging modality require complementary or alternative imaging techniques. Hybrid cardiac imaging was initially introduced to integrate anatomical and functional information to enhance the diagnostic performance, and lately employed as a strategy for comprehensive assessment of the underlying pathophysiology of diseases. More recently, the utility of computed tomography has grown in diversity, and emerged from being an exploratory technique allowing functional measurement such as stress dynamic perfusion. Cardiac magnetic resonance imaging (CMR) is widely accepted as a robust tool for evaluation of cardiac function, fibrosis, and edema, yielding high spatial resolution and soft-tissue contrast. However, the use of intravenous contrast materials is typically required for accurate diagnosis with these imaging modalities, despite the associated risk of renal toxicity. Nuclear cardiology, established as a molecular imaging technique, has advantages in visualization of the disease-specific biological process at cellular level using numerous probes without requiring contrast materials. Various imaging modalities should be appropriately used sequentially to assess concomitant disease and the progression over time. Therefore, simultaneous evaluation combining high spatial resolution and disease-specific imaging probe is a useful approach to identify the regional activity and the stage of the disease. Given the recent advance and potential of multiparametric CMR and novel nuclide tracers, hybrid positron emission tomography MR is becoming an ideal tool for disease-specific imaging.

Impact of height difference between coronary ostium and location of intracoronary pressure sensor on fractional flow reserve measurements

BACKGROUND

During fractional flow reserve (FFR) measurements, distal coronary pressure (Pd) can be influenced by hydrostatic pressure changes resulting from the height difference (HD) between the coronary ostium and the location of the distal pressure sensor.

AIMS

We investigated the effect of aortocoronary HD on the FFR measurements in each coronary artery.

METHODS

In this retrospective cohort study, we analyzed 257 patients who underwent FFR measurements and coronary computed tomography (CCTA) within a year. Using CCTA, we measured HD as the vertical distance between the coronary ostium and a matched point of the distal coronary pressure sensor identified on coronary angiography.

RESULTS

The location of the Pd sensor was higher than the coronary ostium in the left anterior descending artery (LAD) (-4.64 ± 1.15 cm) and lower than the coronary ostium in the left circumflex artery (LCX) (2.54 ± 1.05 cm) and right coronary artery (RCA) (2.03 ± 1.28 cm). The corrected FFR values by HD were higher in the LAD (0.78 ± 0.09 to 0.82 ± 0.09, P<0.01) and lower in the LCX and RCA than the original FFR values (0.87 ± 0.07 to 0.85 ± 0.08, P<0.01; 0.87 ± 0.10 to 0.86 ± 0.10, P<0.01, respectively). Using an FFR cut-off value of 0.8, the concordance rates between the FFR and corrected FFR values were 77.8%, 95.2%, and 100% in the LAD, LCX, and RCA, respectively.

CONCLUSION

HD between the coronary ostium and the distal coronary pressure sensor may affect FFR measurements and FFR-guided treatment decisions for coronary artery disease.

Diagnostic and Prognostic Value of Stress Cardiovascular Magnetic Resonance Imaging in Patients With Known or Suspected Coronary Artery Disease: A Systematic Review and Meta-analysis

Importance

The clinical utility of stress cardiovascular magnetic resonance imaging (CMR) in stable chest pain is still debated, and the low-risk period for adverse cardiovascular (CV) events after a negative test result is unknown.

Objective

To provide contemporary quantitative data synthesis of the diagnostic accuracy and prognostic value of stress CMR in stable chest pain.

Data Sources

PubMed and Embase databases, the Cochrane Database of Systematic Reviews, PROSPERO, and the ClinicalTrials.gov registry were searched for potentially relevant articles from January 1, 2000, through December 31, 2021.

Study Selection

Selected studies evaluated CMR and reported estimates of diagnostic accuracy and/or raw data of adverse CV events for participants with either positive or negative stress CMR results. Prespecified combinations of keywords related to the diagnostic accuracy and prognostic value of stress CMR were used. A total of 3144 records were evaluated for title and abstract; of those, 235 articles were included in the full-text assessment of eligibility. After exclusions, 64 studies (74 470 total patients) published from October 29, 2002, through October 19, 2021, were included.

Data Extraction and Synthesis

This systematic review and meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses.

Main Outcomes and Measures

Diagnostic odds ratios (DORs), sensitivity, specificity, area under the receiver operating characteristic curve (AUROC), odds ratio (OR), and annualized event rate (AER) for all-cause death, CV death, and major adverse cardiovascular events (MACEs) defined as the composite of myocardial infarction and CV death.

Results

A total of 33 diagnostic studies pooling 7814 individuals and 31 prognostic studies pooling 67 080 individuals (mean [SD] follow-up, 3.5 [2.1] years; range, 0.9-8.8 years; 381 357 person-years) were identified. Stress CMR yielded a DOR of 26.4 (95% CI, 10.6-65.9), a sensitivity of 81% (95% CI, 68%-89%), a specificity of 86% (95% CI, 75%-93%), and an AUROC of 0.84 (95% CI, 0.77-0.89) for the detection of functionally obstructive coronary artery disease. In the subgroup analysis, stress CMR yielded higher diagnostic accuracy in the setting of suspected coronary artery disease (DOR, 53.4; 95% CI, 27.7-103.0) or when using 3-T imaging (DOR, 33.2; 95% CI, 19.9-55.4). The presence of stress-inducible ischemia was associated with higher all-cause mortality (OR, 1.97; 95% CI, 1.69-2.31), CV mortality (OR, 6.40; 95% CI, 4.48-9.14), and MACEs (OR, 5.33; 95% CI, 4.04-7.04). The presence of late gadolinium enhancement (LGE) was associated with higher all-cause mortality (OR, 2.22; 95% CI, 1.99-2.47), CV mortality (OR, 6.03; 95% CI, 2.76-13.13), and increased risk of MACEs (OR, 5.42; 95% CI, 3.42-8.60). After a negative test result, pooled AERs for CV death were less than 1.0%.

Conclusion and Relevance

In this study, stress CMR yielded high diagnostic accuracy and delivered robust prognostication, particularly when 3-T scanners were used. While inducible myocardial ischemia and LGE were associated with higher mortality and risk of MACEs, normal stress CMR results were associated with a lower risk of MACEs for at least 3.5 years.

Non-Contrast and Contrast-Enhanced Cardiac Computed Tomography Imaging in the Diagnostic and Prognostic Evaluation of Coronary Artery Disease

In recent decades, cardiac computed tomography (CT) has emerged as a powerful non-invasive tool for risk stratification, as well as the detection and characterization of coronary artery disease (CAD), which remains the main cause of morbidity and mortality in the world. Advances in technology have favored the increasing use of cardiac CT by allowing better performance with lower radiation doses. Coronary artery calcium, as assessed by non-contrast CT, is considered to be the best marker of subclinical atherosclerosis, and its use is recommended for the refinement of risk assessment in low-to-intermediate risk individuals. In addition, coronary CT angiography (CCTA) has become a gate-keeper to invasive coronary angiography (ICA) and revascularization in patients with acute chest pain by allowing the assessment not only of the extent of lumen stenosis, but also of its hemodynamic significance if combined with the measurement of fractional flow reserve or perfusion imaging. Moreover, CCTA provides a unique incremental value over functional testing and ICA by imaging the vessel wall, thus allowing the assessment of plaque burden, composition, and instability features, in addition to perivascular adipose tissue attenuation, which is a marker of vascular inflammation. There exists the potential to identify the non-obstructive lesions at high risk of progression to plaque rupture by combining all of these measures.

Is it the Time to Move Towards Coronary Computed Tomography Angiography-Derived Fractional Flow Reserve Guided Percutaneous Coronary Intervention? The Pros and Cons

Coronary artery disease is the leading cause of mortality worldwide. Diagnosis is conventionally performed by direct visualization of the arteries by invasive coronary angiography (ICA), which has inherent limitations and risks. Measurement of fractional flow reserve (FFR) has been suggested for a more accurate assessment of ischemia in the coronary artery with high accuracy for determining the severity and decision on the necessity of intervention. Nevertheless, invasive coronary angiography-derived fractional flow reserve (ICA-FFR) is currently used in less than one-third of clinical practices because of the invasive nature of ICA and the need for additional equipment and experience, as well as the cost and extra time needed for the procedure. Recent technical advances have moved towards non-invasive high-quality imaging modalities, such as magnetic resonance, single-photon emission computed tomography, and coronary computed tomography (CT) scan; however, none had a definitive modality to confirm hemodynamically significant coronary artery stenosis. Coronary computed tomography angiography (CCTA) can provide accurate anatomic and hemodynamic data about the coronary lesion, especially calculating fractional flow reserve derived from CCTA (CCTA-FFR). Although growing evidence has been published regarding CCTA-FFR results being comparable to ICA-FFR, CCTA-FFR has not yet replaced the invasive conventional angiography, pending additional studies to validate the advantages and disadvantages of each diagnostic method. Furthermore, it has to be identified whether revascularization of a stenotic lesion is plausible based on CCTA-FFR and if the therapeutic plan can be determined safely and accurately without confirmation from invasive methods. Therefore, in the present review, we will outline the pros and cons of using CCTA-FFR vs. ICA-FFR regarding diagnostic accuracy and treatment decision-making.

Uric Acid to High-Density Lipoprotein Cholesterol Ratio is a Novel Marker to Predict Functionally Significant Coronary Artery Stenosis

Background

Intermediate coronary stenosis (ICS) is defined as a visually estimated percentage of diameter stenosis ranging between 40% and 70% by conventional coronary angiography (CAG). Whether to perform percutaneous coronary intervention (PCI) for these lesions is a challenge in clinical practice. The fractional flow reserve (FFR) can guide treatment by determining the functional significance of ICS. Studies have shown that some clinical indicators can be used to predict FFR. However, there is little research on this in the Chinese population.

Methods

We retrospectively analyzed 690 patients who underwent FFR measurements to determine the functional significance of a single ICS. Patients were divided into 2 groups: FFR ≤0.8 (n = 280) and FFR >0.8 (n = 410). We compared the clinical factors between the two groups and performed multivariate logistic regression analyses to explore the risk factors. In addition, receiver-operating characteristic (ROC) curves were constructed for FFR ≤0.8 diagnoses.

Results

The mean UHR (uric acid to high-density lipoprotein cholesterol ratio) level was significantly higher in the FFR ≤0.8 group (p < 0.001). UHR corrects negatively with FFR (r = −0.44, p < 0.001). High-level UHR was an independent risk factor for the FFR ≤0.8 (OR = 7.17, 95% CI 4.17–12.34). The area under the curve (AUC) of the UHR diagnostic capacity for the FFR ≤0.8 is 0.77, with 77.3% sensitivity and 68.2% specificity.

Conclusion

UHR levels were significantly increased in patients with hemodynamically significant coronary lesions. UHR is a novel predictor of functionally significant lesions in patients with a single-vessel disease of ICS.

Impact of overestimation of fractional flow reserve by adenosine on anatomical-functional mismatch

Adenosine occasionally results in overestimation of fractional flow reserve (FFR) values, compared with other hyperemic stimuli. We aimed to elucidate the association of overestimation of FFR by adenosine with anatomically significant but functionally non-significant lesions (anatomical-functional mismatch) and its influence on reclassification of functional significance. Distal-to-aortic pressure ratio (Pd/Pa) was measured using adenosine (Pd/PaADN) and papaverine (Pd/PaPAP) in 326 patients (326 vessels). The overestimation of FFR was calculated as Pd/PaADN-Pd/PaPAP. The anatomical-functional mismatch was defined as diameter stenosis > 50% and Pd/PaADN > 0.80. Reclassification was indicated by Pd/PaADN > 0.80 and Pd/PaPAP ≤ 0.80. The mismatch (n = 72) had a greater overestimation of FFR than the non-mismatch (n = 99): median 0.02 (interquartile range 0.01-0.05) versus 0.01 (0.00-0.04), p = 0.014. Multivariable analysis identified the overestimation of FFR (p = 0.003), minimal luminal diameter (p = 0.001), and non-left anterior descending artery (LAD) location (p < 0.001) as determinants of the mismatch. Reclassification was indicated in 29% of the mismatch and was more frequent in the LAD than in the non-LAD (52% vs. 20%, p = 0.005). The overestimation of FFR is an independent determinant of anatomical-functional mismatch. Anatomical-functional mismatch, specifically in the LAD, may suggest a false-negative result.

Functional Evaluation of Intermediate Coronary Lesions with Integrated Computed Tomography Angiography and Invasive Angiography in Patients with Stable Coronary Artery Disease

Background and objectives

The hemodynamic evaluation of coronary stenoses undergoes a transition from wire-based invasive measurements to image-based computational assessments. However, fractional flow reserve (FFR) values derived from coronary CT angiography (CCTA) and angiography-based quantitative flow ratio have certain limitations in accuracy and efficiency, preventing their widespread use in routine practice. Hence, we aimed to investigate the diagnostic performance of FFR derived from the integration of CCTA and invasive angiography (FFR_CT-angio) with artificial intelligence assistance in patients with stable coronary artery disease (CAD).

Methods

Forty stable CAD patients with 67 target vessels (50%-90% diameter stenosis) were included in this single-center retrospective study. All patients underwent CCTA followed by coronary angiography with FFR measurement within 30 days. Both CCTA and angiographic images were combined to generate a three-dimensional reconstruction of the coronary arteries using artificial intelligence. Subsequently, functional assessment was performed through a deep learning algorithm. FFR was used as the reference.

Results

FFR_CT-angio values were significantly correlated with FFR values (r = 0.81, P < 0.001, Spearman analysis). Per-vessel diagnostic accuracy of FFR_CT-angio was 92.54%. Sensitivity and specificity in identifying ischemic lesions were 100% and 88.10%, respectively. Positive predictive value and negative predictive value were 83.33% and 100%, respectively. Moreover, the diagnostic performance of FFR_CT-angio was satisfactory in different target vessels and different segment lesions.

Conclusions

FFR_CT-angio exhibits excellent diagnostic performance of identifying ischemic lesions in patients with stable CAD. Combining CCTA and angiographic imaging, FFR_CT-angio may represent an effective and practical alternative to invasive FFR in selected patients.

Diagnostic Performance of CT FFR With a New Parameter Optimized Computational Fluid Dynamics Algorithm From the CT-FFR-CHINA Trial: Characteristic Analysis of Gray Zone Lesions and Misdiagnosed Lesions

To assess the diagnostic performance of fractional flow reserve (FFR) derived from coronary computed tomography angiography (CTA) (CT-FFR) obtained by a new computational fluid dynamics (CFD) algorithm to detect ischemia, using FFR as a reference, and analyze the characteristics of “gray zone” and misdiagnosed lesions. This prospective multicenter clinical trial (NCT03692936, https://clinicaltrials.gov/) analyzed 317 patients with coronary stenosis between 30 and 90% in 366 vessels from five centers undergoing CTA and FFR between November 2018 and March 2020. CT-FFR were obtained from a CFD algorithm (Heartcentury Co., Ltd., Beijing, China). Diagnostic performance of CT-FFR and CTA in detecting ischemia was assessed. Coronary atherosclerosis characteristics of gray zone and misdiagnosed lesions were analyzed. Per-vessel sensitivity, specificity and accuracy for CT-FFR and CTA were 89.9, 87.8, 88.8% and 89.3, 35.5, 60.4%, respectively. Accuracy of CT-FFR was 80.0% in gray zone lesions. In gray zone lesions, lumen area and diameter were significantly larger than lesions with FFR < 0.76 (both p < 0.001), lesion length, non-calcified and calcified plaque volume were all significantly higher than non-ischemic lesions (all p < 0.05). In gray zone lesions, Agatston score (OR = 1.009, p = 0.044) was the risk factor of false negative results of CT-FFR. In non-ischemia lesions, coronary stenosis >50% (OR = 2.684, p = 0.03) was the risk factor of false positive results. Lumen area (OR = 0.567, p = 0.02) and diameter (OR = 0.296, p = 0.03) had a significant negative effect on the risk of false positive results of CT-FFR. In conclusion, CT-FFR based on the new parameter-optimized CFD model provides better diagnostic performance for lesion-specific ischemia than CTA. For gray zone lesions, stenosis degree was less than those with FFR < 0.76, and plaque load was heavier than non-ischemic lesions.

Quantifying tissue perfusion after peripheral endovascular procedures: Novel tissue perfusion endpoints to improve outcomes

Peripheral artery disease (PAD) is a flow-limiting condition caused by narrowing of the peripheral arteries typically due to atherosclerosis. It affects almost 200 million people globally with patients either being asymptomatic or presenting with claudication or critical or acute limb ischemia. PAD-affected patients display increased mortality rates, rendering their management critical. Endovascular interventions have proven crucial in PAD treatment and decreasing mortality and have significantly increased over the past years. However, for the functional assessment of the outcomes of revascularization procedures for the treatment of PAD, the same tests that have been used over the past decades are still being employed. Those only allow an indirect evaluation, while an objective quantification of limb perfusion is not feasible. Standard intraarterial angiography only demonstrates post-intervention vessel patency, hence is unable to accurately estimate actual limb perfusion and is incapable of quantifying treatment outcome. Therefore, there is a significant necessity for real-time objectively measurable procedural outcomes of limb perfusion that will allow vascular experts to intraoperatively quantify and assess outcomes, thus optimizing treatment, obviating misinterpretation, and providing significantly improved clinical results. The purpose of this review is to familiarize readers with the currently available perfusion-assessment methods and to evaluate possible prospects.

Functional assessment of intermediate coronary artery stenosis with 4-Fr catheters

The 4-Fr catheter system is not recommended for invasive functional assessment of coronary artery stenosis, because it tends to distort the aortic waveform. This study aimed to identify the incidence of aortic waveform distortion and a feasible method for correct diagnosis of coronary artery stenosis with a 4-Fr catheter. We retrospectively investigated 178 lesions with intermediate coronary artery stenosis. Non-hyperemic distal coronary artery pressure (Pd) and aortic pressure (Pa) were measured with a 4-Fr diagnostic or 6-Fr guiding catheter before and after saline flush. The mean Pd/mean Pa (Pd/Pa) and instantaneous wave-free ratio (iFR) were calculated before and after flushing. We compared the effect of flushing on the changes in Pd/Pa and iFR between the 4-Fr diagnostic and 6-Fr guiding catheters. Using the 4-Fr diagnostic catheter, there was a significant decrease in incidence of aortic waveform distortion from 42.0% (47 lesions) before flushing to 1.8% (2 lesions) after flushing (p < 0.001); the incidence was only 3.0% before saline flush and decreased to 0% after saline flush when using the 6-Fr guiding catheter. The presence of aortic waveform distortion influenced the iFR when the 4-Fr system was used. Functional measurements with the 4-Fr diagnostic catheter require adequate saline flush to remove the influence of aortic waveform distortion.

Does fractional flow reserve overestimate severity of LAD lesions?

BACKGROUND

Fractional Flow Reserve (FFR) is increasingly used to estimate the severity of coronary stenoses, prior to coronary revascularization. However, it has been suggested that FFR overestimates the severity of Left Anterior Descending (LAD) lesions. Our aim was to verify whether in patients without ischemia on Myocardial Perfusion Imaging, FFR of the LAD is more often abnormal in comparison to FFR of other coronary arteries.

METHODS

Prospective cohort study of consecutive patients who underwent FFR measurement because of persistent or worsening of angina complaints, within 6 months after normal Myocardial Perfusion Imaging. FFR measurements of a graft or diagonal branch were excluded. A FFR ≤ 0.80 denoted a functionally relevant stenosis.

RESULTS

In 133 patients, 167 FFR measurements were performed, of which 85 in the LAD. Mean age of the patients was 64.8 ± 10.5 years, 40% were women. There were no differences in baseline characteristics between patients undergoing LAD and non-LAD measurements. An abnormal FFR was observed in 35.3% of the LAD measurements, compared to 9.8% in the non-LAD measurements (P = 0.001). Also after adjusting for age and gender, the FFR remained more frequently abnormal in the LAD with OR 5.2 (95% CI 2.2 to 12.3). Of the abnormal FFR LAD measurements, 70% were visually considered non-obstructive on invasive angiography.

CONCLUSIONS

In selected patients without ischemia on MPI, FFR measurement of the LAD is significantly more often abnormal. The majority of these patients has no obstructive lesions on invasive angiography. Possibly, FFR overestimates severity of LAD lesions, with risk of unnecessary revascularization.

Effect of random deferral of percutaneous coronary intervention in patients with diabetes and stable ischaemic heart disease

BACKGROUND

In stable ischaemic heart disease (SIHD), measurement of fractional flow reserve (FFR) to guide selection of lesions for percutaneous coronary intervention (PCI) reduces death and myocardial infarction (MI) compared with angiographic guidance. However, it is unknown if the improved outcomes are due to avoidance of stenting of physiologically insignificant lesions or are a by-product of placing fewer stents.

METHODS

We developed a Monte Carlo simulation using the PCI strata of the Bypass Angioplasty Revascularization Investigation 2 Diabetes study to investigate how random deferral of PCI impacts outcomes. To simulate deferral, a randomly selected group of patients randomised to PCI were removed and replaced by an equal number of randomly selected patients randomised to intensive medical therapy (IMT) using a random number generator in Python's NumPy module. The primary endpoint was the rate of death or non-fatal MI at 1 year.

RESULTS

Death/MI at 1 year occurred in 8.3% of 798 patients in the PCI group and 5.1% of 807 patients in the IMT control group (p=0.02). Following 10 000 iterations of random replacement of 10%, 20%, 30% or 40% of PCI patients with randomly selected IMT patients, the rate of death/MI at 1 year progressively declined from 8.3% to 8.0%, 7.6%, 7.3% and 7.0%, respectively.

CONCLUSIONS

In this simulation model, random deferral of PCI procedures in SIHD progressively reduced death/MI as the percentage of procedures deferred increases. FFR-guided deferral of PCI may improve outcomes as a result of placing fewer stents and be unrelated to the haemodynamic severity of lesions.

Prognostic Value of Resting Distal-to-Aortic Coronary Pressure in Clinical Practice

BACKGROUND

The resting distal-to-aortic coronary pressure ratio (Pd/Pa) is a universally available, hyperemia-free physiological index of coronary stenosis. We investigated clinical outcomes according to resting Pd/Pa versus hyperemic fractional flow reserve (FFR).

METHODS

From the IRIS-FFR (Interventional Cardiology Research Incooperation Society Fractional Flow Reserve) registry, 7014 lesions in 4707 patients with valid resting Pd/Pa and FFR were included in this study. The primary outcome was major adverse cardiac events (MACE; a composite of cardiac death, myocardial infarction, and repeat intervention). The MACE rate was compared among resting Pd/Pa ≤0.92 and FFR ≤0.80. A marginal Cox model accounted for correlated data in patients with multiple lesions.

RESULTS

During a median follow-up of 2.0 years, 223 MACEs occurred. Resting Pd/Pa was an independent predictor for the occurrence of MACE (adjusted hazard ratio [aHR], 1.89 [95% CI, 1.32-2.71]; P=0.001) over clinical and angiographic variables. When resting Pd/Pa and FFR were added into a multivariable model, MACE was no longer significantly associated with resting Pd/Pa (aHR, 1.35 [95% CI, 0.93-1.97]; P=0.12) but remained to be associated with FFR (aHR, 2.34 [95% CI, 1.56-3.54]; P<0.001). Compared with lesions with normal value of resting Pa/Pa and FFR, lesions with abnormal values of either resting Pd/Pa (aHR, 2.12 [95% CI, 1.17-3.84]; P=0.014) or FFR (aHR, 2.32 [95% CI, 1.52-3.55]; P<0.001) or both (aHR, 2.37 [95% CI, 1.57-3.57]; P<0.001) showed a significantly increased risk of the occurrence of MACE.

CONCLUSIONS

Resting Pd/Pa appeared to be a less-robust prognostic index than FFR. Resting Pd/Pa could be used as a prognostic index when hyperemic agents are contraindicated or not easily available. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT01366404.

Optimizing the Technique for Invasive Fractional Flow Reserve to Assess Lesion-Specific Ischemia

Background:

Invasive fractional flow reserve (FFR INV ) is the standard technique for assessing myocardial ischemia. Pressure distortions and measurement location may influence FFR INV interpretation. We report a technique for performing invasive fractional flow reserve (FFR INV ) by minimizing pressure distortions and identifying the proper location to measure FFR INV .

Methods:

FFR INV recordings were obtained prospectively during manual hyperemic pullback in 100 normal and diseased coronary arteries with single stenosis, using 4 measurements from the terminal vessel, distal-to-the-lesion, proximal vessel, and guiding catheter. FFR INV profiles were developed by plotting FFR INV values ( y -axis) and site of measurement ( x -axis), stratified by stenosis severity. FFR INV ≤0.8 was considered positive for lesion-specific ischemia.

Results:

Erroneous FFR INV values were observed in 10% of vessels because of aortic pressure distortion and in 21% because of distal pressure drift; these were corrected by disengagement of the guiding catheter and re-equalization of distal pressure/aortic pressure, respectively. There were significant declines in FFR INV from the proximal to the terminal vessel in normal and stenotic coronary arteries ( P <0.001). The rate of positive FFR INV was 41% when measured from the terminal vessel and 20% when measured distal-to-the-lesion ( P <0.001); 41.5% of positive terminal measurements were reclassified to negative when measured distal-to-the-lesion. Measuring FFR INV 20 to 30 mm distal-to-the-lesion (rather than from the terminal vessel) can reduce errors in measurement and optimize the assessment of lesion-specific ischemia.

Conclusions:

Meticulous technique (disengagement of the guiding catheter, FFR INV pullback) is required to avoid erroneous FFR INV , which occur in 31% of vessels. Even with optimal technique, FFR INV values are influenced by stenosis severity and the site of pressure measurement. FFR INV values from the terminal vessel may overestimate lesion-specific ischemia, leading to unnecessary revascularization.

Assessment of Cerebral Vasodilatory Capacity as Part of Catheter-Based Cerebral Angiography

BACKGROUND AND PURPOSE

Cerebral vasodilatory capacity assessment for risk stratification in patients with extracranial arterial stenosis or occlusion may be useful. We describe a new method that assesses cerebral vasodilatory capacity as part of catheter-based cerebral angiography.

METHODS

We prospectively assessed regional cerebral blood volume (rCBV) in the arterial distribution of interest using a controlled contrast injection in the common carotid or the subclavian arteries. rCBV maps were created using a predefined algorithm based on contrast distribution in the venous phase (voxel size: .466 mm³ ). rCBV maps were acquired again after selective administration of intra-arterial nicardipine (2.0 mg) distal to the stenosis. Two independent observers graded the change in rCBV in 10 predefined anatomical regions within the tributaries of the artery of interest (0 = reduction, 1 = no change, 2 = increase) and total rCBV change scores were summated.

RESULTS

Twenty-five patients with internal carotid artery stenosis (n = 18; 0-90% in severity) or extracranial vertebral artery stenosis (n = 7; 0-100% in severity) were assessed. There was an increase in rCBV in a tributary of the artery of interest in 18 of 25 after intra-arterial nicardipine (mean score: 11.98; range 0-19.5). There was no change or decrease in rCBV in 7 of 25 patients. The mean rCBV change score was similar in patients with an assessment of internal carotid artery or vertebral artery distributions (12.2 ± 5.3; 11.4 ± 2.5; P = .68).

CONCLUSION

Selective vasodilatory response to intra-arterial nicardipine in the affected arterial distribution during catheter-based cerebral angiography may provide new data for risk stratification.

Fractional flow reserve and frequency of PCI in patients with coronary artery disease

BACKGROUND

Fractional flow reserve (FFR) guided percutaneous coronary intervention (PCI) has been validated in patients with stable coronary artery disease (CAD) but has not yet been verified under specific conditions such as heart failure or microvascular dysfunction. The aim of the present study was to examine the influence of specific patient comorbidities on FFR values and thus the frequency of PCI in patients with intermediate coronary stenosis.

METHODS

A total of 652 patients with CAD and intermediate coronary stenosis who were assessed for FFR were included in this retrospective study. In a subgroup analysis, specific comorbidities such as heart failure with non-ST-segment-elevated acute coronary syndrome (NSTE-ACS), heart failure, diabetes mellitus, atrial fibrillation (AF), and left ventricular hypertrophy (LVH) were considered.

RESULTS

In all lesions with an FFR ≤ 0.80 (n = 227/808, 28.1%), PCI was performed using drug-eluting stents. Pathological FFR values (FFR ≤ 0.80) before PCI were most frequently observed in the left anterior descending artery (LAD; n = 168/418, 39.9%) followed by the right coronary artery (RCA; n = 37/178, 20.7%) and the left circumflex artery (LCX; 22/223, 9.8%). The comorbidities NSTE-ACS (p = 0.28), heart failure with reduced ejection fraction (HFrEF; p = 0.63), heart failure with preserved ejection fraction (HFpEF; p = 0.3719), diabetes mellitus (p = 0.177), or LVH (p = 0.407) had no major impact on the occurrence of pathological FFR values; there was also no association between FFR and the occurrence of lesions in the different target vessels.

CONCLUSION

The occurrence of pathological FFR values, most frequently documented in the LAD, was the same in patients with or without HFrEF, HFpEF, diabetes mellitus, AF, and LVH, demonstrating that these comorbidities did not influence FFR values and, thus, the indication for PCI.

Prognostic Role of Admission C-Reactive Protein Level as a Predictor of In-Hospital Mortality in Type-A Acute Aortic Dissection: A Meta-Analysis

BACKGROUND

Acute aortic dissection (AD) is a lethal vascular disease, accounting for over 90% cases of acute aortic syndrome. Despite advances in understanding associated risk factors, the long-term prognosis for AD patients is still poor. Several prognostic biomarkers have been used for AD as per the IRAD, such as older age (>70 years), onset of chest pain and hypotension, but they are not effective in all patients. Instead, C-reactive protein (CRP) is a consistent inflammatory marker. CRP levels are abnormally increased in AD. However, the prognostic value of serum CRP level in AD remains unclear.

OBJECTIVE

To perform a systematic review and meta-analysis (registration no CRD42017056205) to evaluate whether CRP is a biomarker associated with in-hospital mortality in type-A AD.

METHODS

PubMed, Web of Science, CNKI, SciELO, and EMBASE were searched for papers published from January 2000 to October 2017 for studies on the prognostic role of CRP at admission in type-A AD patients. Outcome data were extracted and pooled hazard ratios (HRs) were calculated.

RESULTS

18 (N = 2875 patients) studies met the inclusion criteria. Elevated CRP level was associated with a significantly increased risk of in-hospital mortality in patients with type-A AD (HR = 1.15, 95% CI: 1.06-1.25, p = 0.001). The pooled sensitivity of CRP in type-A AD patients was 77% (95% CI 69%-84%, p < 0.001), and the specificity was 72% (95% CI 66%-78%, p < 0.001).

CONCLUSION

Elevated CRP level is significantly associated with increased risks of in-hospital mortality in patients with type-A AD. CRP is a convenient prognostic factor in type-A AD patients.

Coronary Physiology in the Cardiac Catheterization Laboratory

Coronary angiography has been the principle modality for assessing the severity of atherosclerotic coronary artery disease for several decades. However, there is a complex relationship between angiographic coronary stenosis and the presence or absence of myocardial ischemia. Recent technological advances now allow for the assessment of coronary physiology in the catheterization laboratory at the time of diagnostic coronary angiography. Early studies focused on coronary flow reserve (CFR) but more recent work has demonstrated the physiologic accuracy and prognostic value of the fractional flow reserve (FFR) and instantaneous wave free ratio (iFR) for the assessment of coronary artery disease. These measurements have been validated in large multi-center clinical trials and have become indispensable tools for guiding revascularization in the cardiac catheterization laboratory. The physiological assessment of chest pain in the absence of epicardial coronary artery disease involves coronary thermodilution to obtain the index of microcirculatory resistance (IMR) or Doppler velocity measurement to determine the coronary flow velocity reserve (CFVR). Physiology-based coronary artery assessment brings "personalized medicine" to the catheterization laboratory and allows cardiologists and referring providers to make decisions based on objective findings and evidence-based treatment algorithms. The purpose of this review is to describe the theory, technical aspects, and relevant clinical trials related to coronary physiology assessment for an intended audience of general medical practitioners.

Discordance between pressure drift after wire pullback and intracoronary distal pressure offset affects stenosis physiology appraisal

BACKGROUND

Drift is a well-known issue affecting intracoronary pressure measurements. A small pressure offset at the end of the procedure is generally considered acceptable, while repeat assessment is advised for drift exceeding ±2 mmHg. This practice implies that drift assessed after wire pullback equals that at the time of stenosis appraisal, but this assumption has not been systematically investigated. Our aim was to compare intra-and post-procedural pressure sensor drift and assess benefits of correction for intra-procedural drift and its effect on diagnostic classification.

METHODS

In 70 patients we compared intra- and post-procedural pressure drift for 120 hemodynamic tracings obtained at baseline and throughout the hyperemic response to intracoronary adenosine. Intra-procedural drift was derived from the intercept of the stenosis pressure gradient-velocity relationship. Diagnostic reclassification after correction for intra-procedural drift was assessed for the mean distal-to-aortic pressure ratio at baseline (Pd/Pa) and hyperemia (fractional flow reserve, FFR), and corresponding stenosis resistances.

RESULTS

Post- and intra-procedural drift exceeding the tolerated threshold was observed in 73% and 64% of the hemodynamic tracings, respectively. Discordance in terms of acceptable drift level was present for 42% of the tracings, with avoidable repeat physiological assessment in 25% and unacceptable intra-procedural drift unrecognized at final drift check in 17% of the tracings. Correction for intra-procedural drift caused higher reclassification rates for baseline than hyperemic functional indices.

CONCLUSIONS

Post-procedural pressure drift frequently does not match drift during physiological assessment. Tracing-specific correction for intra-procedural drift can potentially lower the risk of inadvertent diagnostic misclassification and prevent unnecessary repeats.

A New Technique for the Assessment of Cerebral Vasodilatory Capacity as Part of Catheter-Based Cerebral Angiography

BACKGROUND

Previous studies have demonstrated the value of cerebral vasodilatory capacity assessment for risk stratification in patients with extracranial arterial stenosis or occlusion. We describe a new method that assesses cerebral vasodilatory capacity as part of catheter-based cerebral angiography.

METHODS

We assessed regional cerebral blood volume (rCBV) in the arterial distribution of interest using a controlled contrast injection through a diagnostic catheter placed in the common carotid or the subclavian artery. rCBV maps were created using predefined algorithm based on contrast distribution in the venous phase (voxel size 0.466 mm³) into high, intermediate, low, and no detectable rCBV regions. rCBV maps were acquired again after the administration of intra-arterial nicardipine (1.5-2.5 mg), and percentage increases of the area of various grades of rCBV were calculated.

RESULTS

Three patients with internal carotid artery stenosis (32% - 64% in severity) and 1 patient with extracranial vertebral artery stenosis (46% in severity) were assessed. There was a variable but consistent increase in the area of high rCBV in the ipsilateral hemisphere in 3 patients with internal carotid artery flow (5.5%-24.5%) and the cerebellum (9.6%) in 1 patient with vertebral artery flow assessments. The increase in high rCBV was most prominent in the patient who received 2.5 mg (24.5%) and least prominent in a patient who received 1.5 mg (5.5%) of intra-arterial nicardipine. There was a concurrent reduction in areas of intermediate and low rCBV (shift) in 3 patients, and there was an increase in all areas of rCBV grades (addition) in 1 patient.

CONCLUSIONS

Selective assessment of cerebral vasodilatory response in the affected arterial distribution is feasible during catheter-based cerebral angiography.