The impact of gender on fractional flow reserve measurements

Sex Differences in Clinical Outcomes Associated With Quantitative Flow Ratio-Guided Percutaneous Coronary Intervention

Background

FAVOR III China (Comparison of Quantitative Flow Ratio Guided and Angiography Guided Percutaneous Intervention in Patients with Coronary Artery Disease) reported improved clinical outcomes in quantitative flow ratio (QFR) relative to angiography-guided percutaneous coronary intervention (PCI), but the clinical impact of QFR-guided PCI according to sex remains unknown.

Objectives

The authors sought to compare sex differences in the 2-year clinical benefits of a QFR-guided PCI strategy and to evaluate the differences in outcomes between men and women undergoing contemporary PCI.

Methods

This study involved a prespecified subgroup analysis of the FAVOR III China trial, in which women and men were randomized to a QFR-guided strategy or a standard angiography-guided strategy. Sex differences in clinical benefit of the QFR guidance were analyzed for major adverse cardiac events (MACE), a composite of all-cause death, myocardial infarction, or ischemia-driven revascularization within 2 years.

Results

A total of 1,126 women and 2,699 men were eligible and the occurrence of 2-year MACE was similar between women and men (10.3% vs 10.5%; P = 0.96). Compared with an angiography-guided strategy, a QFR-guided strategy resulted in a 7.9% and 9.7% reduction in PCI rates in men and women, respectively. A QFR-guided strategy resulted in similar relative risk reductions for 2-year MACE in women (8.0% vs 12.7%; HR: 0.62; 95% CI: 0.42-0.90) and men (8.7% vs 12.4%; HR: 0.69; 95% CI: 0.54-0.87) (Pinteraction = 0.61). Furthermore, QFR values were not significantly different between men and women with various angiographic stenosis categories.

Conclusions

A QFR-guided PCI strategy resulted in improved MACE in both men and women at 2 years compared with an angiography-guided PCI strategy. The FAVOR III China Study [FAVOR III China]; (NCT03656848).

Impact of Sex Differences on the Outcomes of Coronary Invasive Physiological Assessment: Long-Term Follow-Up in a Brazilian Population

Objective

This study aimed to evaluate the rate of major adverse cardiac events (MACEs; the sum of death, myocardial infarction, and revascularization rates) according to interventional strategies guided by invasive physiological methods in both sexes in a Brazilian population during long-term follow-up for an average of 2 years.

Methods

This retrospective single-center study included 151 consecutive patients (232 lesions) between January 2018 and January 2022. The participants were divided into two groups: the female group (FG), comprising 59 patients with 88 lesions, and the male group (MG), comprising 92 patients with 144 lesions.

Results

The FG had a greater mean age (FG: 67.96 ± 13.12 vs. MG: 62.36 ± 12.01 years, p = 0.009) and lower mean creatinine clearance (FG: 79.35 ± 38.63 vs. MG: 92.02 ± 38.62 mL/min, p = 0.02) than did the MG. The percentage of lesions in the left main coronary artery was higher in the FG than in the MG (12.5% vs. 2.78%, p = 0.006). The mean follow-up time was longer in the MG than in the FG (795.61 ± 350 vs. 619.19 ± 318 days, respectively; p = 0.001). MACE occurred in 11.86% and 13.04% of patients in the FG and MG, respectively (p = 0.850). Secondary outcomes, such as death, reinfarction, and the need for new revascularization, showed no significant between-sex differences.

Conclusions

Our study demonstrated the safety of invasive physiological methods to determine coronary revascularization in both male and female patients in a Brazilian population, as evidenced by the low rates of adverse cardiac events and death after a long-term follow-up.

Factors Predicting 150 and 200 Microgram Adenosine Requirement during Four Increasing Doses of Intracoronary Adenosine Bolus Fractional Flow Reserve Assessment

Direct intracoronary adenosine bolus is an excellent alternative to intravenous adenosine fractional flow reserve (FFR) measurement. This study, during four increasing adenosine boluses (50, 100, 150, and 200 mcg), aimed to explore clinical and angiographic predictors of coronary stenotic lesions for which the significant ischemic FFR (FFR ≤ 0.8) occurred at 150 and 200 mcg adenosine doses. Data from 1055 coronary lesions that underwent FFR measurement at the Central Chest Institute of Thailand from August 2011 to July 2021 were included. Baseline clinical and angiographic characteristics were analyzed. The FFR ≤ 0.8 occurred at adenosine 150 and 200 mcg boluses in 47 coronary lesions, while the FFR ≤ 0.8 occurred at adenosine 50 and 100 mcg boluses in 186 coronary lesions. After univariable and multivariable logistic regression analyses, four characteristics, including male sex, younger age, non-smoking status, and FFR procedure of RCA, were predictors of the occurrence of FFR ≤ 0.8 at adenosine 150 and 200 mcg doses. Combining all four predictors as a predictive model resulted in an AuROC of 0.72 (95% CI: 0.68–0.76), an 86% negative predictive value. Comparing these four predictors, the FFR procedure of RCA gave the most predictive power, with the AuROC of 0.60 (95% CI: 0.56–0.63).

Improving PCI Outcomes Using Postprocedural Physiology and Intravascular Imaging

Although clinical outcomes after percutaneous coronary intervention (PCI) are improving, the long-term risk for target vessel failure remains concerning. Although the application of intravascular imaging and physiological indexes significantly improves outcomes, their routine use in practice remains limited. Nevertheless, merely using these modalities is not enough, and to truly improve patient outcomes, optimal intravascular dimensions with minimal vascular injury should be targeted. When assessing post-PCI results using either type of physiological or imaging technology, a broad spectrum of stent- and vessel-related anomalies can be expected. As not all of these issues warrant treatment, a profound knowledge of what to expect and how to recognize and when to treat these intraluminal problems is needed. Additionally, promising new modalities such as angiography-derived coronary physiology and hybrid imaging catheters are becoming available. The authors provide an overview of the currently available tools and techniques to define suboptimal PCI and when to apply these technologies to improve outcomes.

Sex Differences in the Non-infarct-Related Artery-Based Quantitative Flow Ratio in Patients With ST-Elevation Myocardial Infarction: A Retrospective Study

Introduction: It has been reported that sex has well-established relationships with the prevalence of coronary artery disease (CAD) and the major adverse cardiovascular events. Compared with men, the difference of coronary artery and myocardial characteristics in women has effects on anatomical and functional evaluations. Quantitative flow ratio (QFR) has been shown to be effective in assessing the hemodynamic relevance of lesions in stable coronary disease. However, its suitability in acute myocardial infarction patients is unknown. This study aimed to evaluate the sex differences in the non-infarct-related artery (NIRA)-based QFR in patients with ST-elevation myocardial infarction (STEMI).

Methods: In this study, 353 patients with STEMI who underwent angiographic cQFR assessment and interventional therapy were included. According to contrast-flow QFR (cQFR) standard operating procedures: reliable software was used to modeling the hyperemic flow velocity derived from coronary angiography in the absence of pharmacologically induced hyperemia. 353 patients were divided into two groups according to sex. A cQFR ≤0.80 was considered hemodynamically significant, whereas invasive coronary angiography (ICA) luminal stenosis ≥50% was considered obstructive. Demographics, clinical data, NIRA-related anatomy, and functional cQFR values were recorded. Clinical outcomes included the NIRA reclassification rate between men and women, according to the ICA and cQFR assessments.

Results: Women were older and had a higher body mass index (BMI) than men. The levels of diastolic blood pressure, troponin I, peak creatine kinase-MB, low-density lipoprotein cholesterol, N terminal pro B-type natriuretic peptide, stent diameter, and current smoking rate were found to be significantly lower in the female group than in the male group. Women had a lower likelihood of a positive cQFR ≤0.80 for the same degree of stenosis and a lower rate of NIRA revascularization. Independent predictors of positive cQFR included male sex and diameter stenosis (DS) >70%.

Conclusions: cQFR values differ between the sexes, as women have a higher cQFR value for the same degree of stenosis. The findings suggest that QFR variations by sex require specific interpretation, as these differences may affect therapeutic decision-making and clinical outcomes.

Contribution of Age-Related Microvascular Dysfunction to Abnormal Coronary: Hemodynamics in Patients With Ischemic Heart Disease

OBJECTIVES

This study sought to investigate the contribution of age-related microcirculatory dysfunction to abnormal coronary hemodynamics in patients with coronary atherosclerosis.

BACKGROUND

Impairment in myocardial blood supply in patients with coronary atherosclerosis can be accentuated due to age-related changes in microcirculatory function.

METHODS

Intracoronary pressure and flow were measured with the Doppler technique in 299 vessels (228 patients), and the thermodilution technique in 120 vessels (99 patients). In 172 patients, Doppler measurements were also performed in unobstructed vessels. Associations of coronary hemodynamics with aging were studied in both the stenosed and unobstructed arteries.

RESULTS

Aging was associated with a progressive increase in minimal microvascular resistance and a progressive decrease in hyperemic flow in both obstructed and nonobstructed coronary arteries. As such, coronary flow reserve decreased with advancing age. Epicardial stenosis severity assessed by resting Pd/Pa, basal stenosis resistance index, and hyperemic stenosis resistance index was equivalent across age groups. By contrast, fractional flow reserve increased with advancing age. Consequently, the adjusted risk of a fractional flow reserve/coronary flow reserve pattern reflective of concomitant focal epicardial and diffuse or microvascular disease (relative risk: 1.6; 95% confidence interval: 1.1 to 2.3; p = 0.017) increased with advancing age, whilst the adjusted risk of a fractional flow reserve/coronary flow reserve pattern reflective of non-flow-limiting stenosis with a healthy microcirculation decreased (relative risk: 0.7; 95% CI: 0.5 to 1.0; p = 0.022).

CONCLUSIONS

Aging is associated with progressive pan-myocardial impairment of coronary vasodilatory capacity due to an increase in minimal microvascular resistance. Concomitant aging-related impairment in microvascular function impacts the pathophysiology of ischemic heart disease in the individual patient and is not adequately identified by hyperemic coronary pressure measurements alone.

Renal dysfunction is associated with lower incidence of positive fractional flow reserve values in patients with severe hypertension

BACKGROUND

Renal dysfunction, an important predictor of cardiovascular mortality, is paradoxically associated with a lower incidence of positive coronary fractional flow reserve (FFR) values, possibly due to renal disease-associated myocardial microvascular dysfunction. It is unknown if this relationship is influenced by arterial hypertension, a condition strongly associated with renal- and microvascular dysfunction.

METHODS

The incidence of positive (<0.81) FFR values was retrospectively evaluated in consecutive patients with intermediate severity coronary artery lesions that were either associating or not associating renal dysfunction (creatinine clearance, CrCl <90 mL/min/1.73 m2), and had mild/moderate or severe arterial hypertension (treated by <3 or ≥3 different drugs).

RESULTS

Positive FFR values were found in 49.5% of the 109 included patients, with a significantly lower incidence in those with renal dysfunction: 23 vs. 31 cases (39.7% vs. 60.8%, P=0.03). However, uni- and multivariate subpopulation analysis evidenced that renal dysfunction was a significant independent predictor of fewer positive FFR results only in severely hypertensive patients (univariate P values for mild/moderate and severe hypertension: 0.80 and <0.01, respectively; multivariate P in severely hypertensive patients: 0.04). This categorization significantly restricted the number of borderline FFR results (0.75-0.80) where measurement interpretation could be challenging because of renal dysfunction (from 13.8% to 4.6% of the whole study population, P=0.03).

CONCLUSIONS

In the current study renal dysfunction was independently associated with a significantly higher incidence of negative FFR results in patients with intermediate severity coronary artery lesions only in the presence of severe arterial hypertension. This observation should be confirmed by large-scale prospective clinical trials.

Quantification of Myocardial Mass Subtended by a Coronary Stenosis Using Intracoronary Physiology

Background:

In patients with stable coronary artery disease, the amount of myocardium subtended by coronary stenoses constitutes a major determinant of prognosis, as well as of the benefit of coronary revascularization. We devised a novel method to estimate partial myocardial mass (PMM; ie, the amount of myocardium subtended by a stenosis) during physiological stenosis interrogation. Subsequently, we validated the index against equivalent PMM values derived from applying the Voronoi algorithm on coronary computed tomography angiography.

Methods:

Based on the myocardial metabolic demand and blood supply, PMM was calculated as follows: PMM (g)=APV×D 2 ×π/(1.24×10 − 3 ×HR×sBP+1.6), where APV indicates average peak blood flow velocity; D, vessel diameter; HR, heart rate; and sBP, systolic blood pressure. We calculated PMM to 43 coronary vessels (32 patients) interrogated with pressure and Doppler guidewires, and compared it with computed tomography–based PMM.

Results:

Median PMM was 15.8 g (Q1, Q3: 11.7, 28.4 g) for physiology-based PMM, and 17.0 g (Q1, Q3: 12.5, 25.9 g) for computed tomography–based PMM ( P =0.84). Spearman rank correlation coefficient was 0.916 ( P <0.001), and Passing-Bablok analysis revealed absence of both constant and proportional differences (coefficient A: −0.9; 95% CI, −4.5 to 0.9; and coefficient B, 1.00; 95% CI, 0.91 to 1.25]. Bland-Altman analysis documented a mean bias of 0.5 g (limit of agreement: −9.1 to 10.2 g).

Conclusions:

Physiology-based calculation of PMM in the catheterization laboratory is feasible and can be accurately performed as part of functional stenosis assessment.

Tako-Tsubo syndrome, spontaneous coronary dissection and microvascular disease: Sex-differences

Up to 50% of the patients undergoing coronary angiography present no epicardial disease. Most of these patients are women. Takotsubo cardiomyopathy, coronary microvascular dysfunction, and spontaneous coronary artery dissection are the most common syndromes that affect these patients. Their mechanisms are complex, with a interplay between neurohormonal factors and a number of other systems. The present review describes how changes in the estrogen state may lead to changes in vasomotor tone and endothelial dysfunction which result in coronary epicardial and microvascular spasm and coronary arterial wall instability in these three conditions. The sex-dependent differences in prevalence, pathogenesis, and prognosis are described.

Impact of increasing dose of intracoronary adenosine on peak hyperemia duration during fractional flow reserve assessment

BACKGROUND

Fractional Flow Reserve (FFR) is currently indicated as a first line strategy for the functional assessment of intermediate coronary stenoses. However, the protocol for inducing hyperemia still lacks standardization. Intracoronary adenosine boli, with a progressive increase to high-dosage, have been proposed as a sensitive and accurate strategy for the classification of coronary stenoses, although being potentially affected by the achievement of plateau of the effect and by a less prolonged and stable hyperemia as compared to intravenous administration. Therefore, the aim of the present study was to define the conditioning parameters and assess the impact of increasing-dose intracoronary adenosine on peak hyperemia duration in patients undergoing FFR for intermediate coronary stenoses.

METHODS

FFR was assessed in patients with intermediate (40 to 70%) lesions by pressure-recording guidewire (Prime Wire, Volcano), after induction of hyperemia with intracoronary boli of adenosine (from 60 to 1440 μg, with dose doubling at each step). Hyperemic duration was defined as the time for the variation form minimum FFR ± 0.02 and time to recovery till baseline values.

RESULTS

We included 87 patients, undergoing FFR evaluation of 101 lesions. Mean peak hyperemia duration and time to recovery significantly increased with adenosine doses escalation (p = 0.02 and p < 0.001). Peak hyperemia duration and time to recovery with 1440 μg adenosine were 14.5 ± 12.6 s and 45.2 ± 30.7 s, respectively. Hyperemia duration was not related to Quantitative Coronary Angiography (QCA) parameters or FFR values. In fact, a similar increase in the time of hyperemic peak was noted when comparing patients with positive or negative FFR (p_between = 0.87) or patients with lesions < or ≥20 mm (p_between = 0.92) and lesions involving left main coronary or proximal left anterior descending artery (LAD) (p_between = 0.07). A linear relationship was observed between time to recovery and FFR variations, with a greater time to baseline required in patients with FFR ≤ 0.80 (p = 0.003) and in lesions ≥ 20 mm (p = 0.006), but not in LAD/LM lesions (p = 0.55).

CONCLUSIONS

The present study shows a progressive raise in the duration of peak hyperemia and time to recovery, after the administration of increasing doses of intracoronary adenosine for the assessment of FFR. Therefore, considering the potential advantages of a high-dose adenosine protocol, allowing a more prolonged hyperemia and a more precise and reliable measurement of FFR, further larger studies with such FFR strategy should certainly be advocated to confirm its safety and benefits, before its routinely use recommendation.

Sex Differences in Adenosine-Free Coronary Pressure Indexes: A CONTRAST Substudy

OBJECTIVES

The goal of this study was to investigate sex differences in adenosine-free coronary pressure indexes.

BACKGROUND

Several adenosine-free coronary pressure wire indexes have been proposed to assess the functional significance of coronary artery lesions; however, there is a theoretical concern that sex differences may affect diagnostic performance because of differences in resting flow and distal myocardial mass.

METHODS

In this CONTRAST (Can Contrast Injection Better Approximate FFR Compared to Pure Resting Physiology?) substudy, contrast fractional flow reserve (cFFR), obtained during contrast-induced submaximal hyperemia, the instantaneous wave-free ratio (iFR), and distal/proximal coronary pressure ratio (Pd/Pa) were compared with fractional flow reserve (FFR) in 547 men and 216 women. Using FFR ≤0.8 as a reference, the diagnostic performance of each index was compared.

RESULTS

Men and women had similar diameter stenosis (p = 0.78), but women were less likely to have FFR ≤0.80 than men (42.5% vs. 51.5%, p = 0.04). Sensitivity was similar among cFFR, iFR, and Pd/Pa when comparing women and men, respectively (cFFR, 77.5% vs. 75.3%; p = 0.69; iFR, 84.9% vs. 79.4%; p = 0.30; Pd/Pa, 78.8% vs. 77.3%; p = 0.78). cFFR was more specific than iFR or Pd/Pa regardless of sex (cFFR, 94.3% vs. 95.8%; p = 0.56; iFR, 75.6% vs. 80.1%; p = 0.38; Pd/Pa, 80.6% vs. 78.7%; p = 0.69). By receiver-operating characteristic curve analysis, cFFR provided better diagnostic accuracy than resting indexes irrespective of sex (p ≤ 0.0001).

CONCLUSIONS

Despite the theoretical concern, the diagnostic sensitivity and specificity of cFFR, iFR, and Pd/Pa did not differ between the sexes. Irrespective of sex, cFFR provides the best diagnostic performance.

Stable Ischemic Heart Disease in Women

PURPOSE OF THE REVIEW

Paradoxically, although women have a lower burden of coronary atherosclerosis, they experience more symptoms, more frequent hospitalizations, and a worse prognosis compared to men. This is in part due to biological variations in pathophysiology between the two sexes, and in part related to inadequate understanding of these differences, subconscious referral bias, and suboptimal application of existing women-specific guidelines. We sought to review the contemporary literature and provide an update on risk assessment, diagnosis, and management of IHD in women.

RECENT FINDINGS

IHD in women is often secondary to diffuse non-obstructive atherosclerosis, coronary spasm, inflammation, and endothelial and microvascular dysfunction, and less commonly due to the male pattern of flow-limiting epicardial stenosis. Both IHD patterns likely represent sex-specific manifestations of the same disease process. Additionally, there is a differential expression of risk factors and symptoms between men and women. Application of male-pattern IHD risk factors and presentation to women contributes to under-recognition, under-testing, and under-treatment of IHD in women compared to men. Traditional diagnostic evaluation has focused on detection of epicardial disease, amenable to revascularization. Our improved understanding of sex-specific pathophysiology of IHD has enabled us to also develop tools for detection of microvascular disease. Advances in stress MRI, flow quantification on stress PET, and provocative invasive angiography have filled this void and offer important diagnostic and prognostic information. Despite our improved understanding of sex-specific differences in presentation, risk factors, pathophysiology, diagnostic testing, and management strategies of IHD, women with IHD continue to experience worse outcomes than men. This disparity underscores the need for improved research and understanding of biological sex differences, elimination of subconscious gender bias in referral patterns, and improved application of existing research into clinical practice.

The relationship between the basal coronary translesional pressure ratio and fractional flow reserve

AIM

Fractional flow reserve (FFR) allows for physiological definition of coronary lesion severity but requires induction of maximal coronary circulation hyperemia with administration of adenosine leading to coronary resistive vessel vasodilatation. However, the hyperemic response to adenosine, and therefore the calculation of FFR, may be affected by dysfunction of the coronary microvasculature. The aim was to define the relationship between basal P_d /P_a and FFR and identify lesion-independent predictors of the change in P_d /P_a with hyperemia.

METHODS AND RESULTS

One hundred and sixty-six consecutive patients undergoing FFR measurement were prospectively enrolled (mean age 62.6 ± 10.3 years, 27% females). Basal P_d /P_a , FFR, and delta P_d /P_a (difference between basal P_d /P_a and FFR) were recorded. Independent predictors of delta P_d /P_a included angiographic lesion severity, lesion length, gender, body mass index, and total cholesterol:HDL cholesterol ratio. The best basal P_d /P_a cutoff value to predict lesion physiological significance was 0.87 (positive predictive value of 100% for an FFR value ≤0.80) and the best cutoff for nonsignificance was 0.93 (negative predictive value of 98% for an FFR value >0.80).

CONCLUSION

The delta P_d /P_a may be affected by patient gender, body mass index, and cholesterol profile. A basal P_d /P_a value of ≥0.93 is highly predictive of an FFR >0.80. Conversely, a basal P_d /P_a value of ≤0.87 is highly predictive of an FFR ≤0.80. © 2017 Wiley Periodicals, Inc.

Fractional flow reserve and resting indices for coronary physiologic assessment: Practical guide, tips, and tricks

Physiologic assessment using fractional flow reserve (FFR) to guide percutaneous coronary interventions (PCI) has been demonstrated to improve clinical outcomes, compared to angiography-guided PCI. Recently, resting indices such as resting Pd/Pa, "instantaneous wave-free ratio", and contrast medium induced FFR have been evaluated for the assessment of the functional consequences of coronary lesions. Herein, we review and discuss the use of FFR and other indices for the functional assessment of coronary lesions. This review will cover theoretical aspects, as well as practical points and common pitfalls related to coronary physiological assessment. © 2017 Wiley Periodicals, Inc.

The influence of sex on microvascular function

A number of studies consistently report higher rates of all clinical outcomes including postinfarction mortality, need for repeat revascularization, and reinfarction in women with cardiovascular diseases than in men. As well, the gender gap in the prevalence of cardiovascular diseases decreases progressively with increasing age. Yet, the diagnosis and treatment of these diseases differ between genders and women remain underdiagnosed for coronary heart disease. In a recent retrospective analysis we showed that, along with vessel under study and age, gender is a determinant of adenosine responses during studies of fractional flow reserve, an effect that was probably due to differences in microvascular function and that influenced the interpretation of fractional flow reserve data. These data demonstrate that not only the clinical presentation is different, but also the diagnostic approach to coronary artery disease might differ between sexes.A gap still exists in the understanding of the mechanisms, awareness, and treatment of coronary artery disease in women, but also, as we show, in the application of diagnostic modalities that are well established in men.

Sex Differences in Fractional Flow Reserve-Guided Revascularization: A Nationwide Analysis

BACKGROUND

Women with coronary artery disease are less likely to be revascularized than men based on angiography alone. Recent studies have shown that female patients have higher fractional flow reserve (FFR) values for a given severity of coronary stenosis. However, gender differences in coronary revascularization rates following FFR assessment are unknown.

METHODS

The nationwide inpatient sample database was used to identify all patients who underwent FFR in the United States between January 2009 and December 2010. We used propensity score matching to compare revascularization rates and in-hospital outcomes among men and women undergoing FFR measurements.

RESULTS

Among 3712 patients who underwent FFR during the study period, 1235 matched pairs of men and women were identified. The overall revascularization rates were lower in women than men (40.1% vs. 52.8%, p < 0.01). Women were less likely to undergo either percutaneous (35.2% vs. 45.6%, p < 0.01) or surgical revascularization following FFR than men (5.2% vs. 7.4%, p = 0.03). Women had a nonsignificant trend toward higher in-hospital mortality (0.8% vs. 0.5%, p = 0.32) and significantly higher rates of access site hematoma formation (2.7% vs. 0.8%, p < 0.01) compared to men.

CONCLUSION

In conclusion, this large nationwide study reveals that coronary revascularization rates are significantly lower in women than in men even after functional assessment with FFR.

Impact of impaired fractional flow reserve after coronary interventions on outcomes: a systematic review and meta-analysis

Background

FFR is routinely used to guide percutaneous coronary interventions (PCI). Visual assessment of the angiographic result after PCI has limited efficacy. Even when the angiographic result seems satisfactory FFR after a PCI might be useful for identifying patients with a suboptimal interventional result and higher risk for poor clinical outcome who might benefit from additional procedures. The aim of this meta-analysis was to investigate available data of studies that examined clinical outcomes of patients with impaired vs. satisfactory fractional flow reserve (FFR) after percutaneous coronary interventions (PCI).

Methods

This meta-analysis was carried out according to the Cochrane Handbook for Systematic Reviews. The Mantel-Haenszel method using the fixed-effect meta-analysis model was used for combining the results. Studies were identified by searching the literature through mid-January, 2016, using the following search terms: fractional flow reserve, coronary circulation, after, percutaneous coronary intervention, balloon angioplasty, stent implantation, and stenting. Primary endpoint was the rate of major adverse cardiac events (MACE). Secondary endpoints included rates of death, myocardial infarction (MI), repeated revascularisation.

Results

Eight relevant studies were found including a total of 1337 patients. Of those, 492 (36.8 %) had an impaired FFR after PCI, and 853 (63.2 %) had a satisfactory FFR after PCI. Odds ratios indicated that a low FFR following PCI was associated with an impaired outcome: major adverse cardiac events (MACE, OR: 4.95, 95 % confidence interval [CI]: 3.39–7.22, p <0.001); death (OR: 3.23, 95 % CI: 1.19–8.76, p = 0.022); myocardial infarction (OR: 13.83, 95 % CI: 4.75–40.24, p <0.0001) and repeated revascularisation (OR: 4.42, 95 % CI: 2.73–7.15, p <0.0001).

Conclusions

Compared to a satisfactory FFR, a persistently low FFR following PCI is associated with a worse clinical outcome. Prospective studies are needed to identify underlying causes, determine an optimal threshold for post-PCI FFR, and clarify whether simple additional procedures can influence the post-PCI FFR and clinical outcome.

Electronic supplementary material

The online version of this article (doi:10.1186/s12872-016-0355-7) contains supplementary material, which is available to authorized users.

When should fractional flow reserve be performed to assess the significance of borderline coronary artery lesions: Derivation of a simplified scoring system

OBJECTIVES

To derive a simplified scoring system (SSS) that can assist in selecting patients who would benefit from the application of fractional flow reserve (FFR).

BACKGROUND

Angiographers base decisions to perform FFR on their interpretation of % diameter stenosis (DS), which is subject to variability. Recent studies have shown that the amount of myocardium at jeopardy is an important factor in determining the degree of hemodynamic compromise.

METHODS

We conducted a retrospective multivariable analysis to identify independent predictors of hemodynamic compromise in 289 patients with 317 coronary vessels undergoing FFR. A SSS was derived using the odds ratios as a weighted factor. The receiver operator characteristics curve was used to identify the optimal cutoff (≥3) to discern a functionally significant lesion (FFR≤0.8).

RESULTS

Male gender, left anterior descending artery apical wrap, disease proximal to lesion, minimal lumen diameter and % DS predicted abnormal FFR (≤0.8) and lesion location in the left circumflex predicted a normal FFR. Using a cutoff score of ≥3 on the SSS, a specificity of 90.4% (95% CI: 83.0-95.3) and a sensitivity of 38.0% (95% CI: 31.5-44.9) was generated with a positive predictive value of 89.0% (95% CI: 80.7%-94.6%) and negative predictive value of 41.6% (95% CI: 35.1%-48.3%).

CONCLUSIONS

The decision to use FFR should be based not only on the % DS but also the size of the myocardial mass jeopardized. A score of ≥3 on the SSS should prompt further investigation with a pressure wire.

Factors Associated With Errors in Visual Estimation of the Functional Significance of Coronary Lesions

INTRODUCTION AND 

OBJECTIVES

Visual angiographic assessment continues to be used when decisions are made on whether to revascularize ambiguous coronary lesions. Multiple factors, other than the degree of stenosis, have been associated with the functional significance of a coronary lesion. The aim of this study was to investigate the ability of interventionists to visually predict the functional significance of a coronary lesion and the clinical and angiographic characteristics associated with errors in prediction.

METHODS

We conducted a concordance study of the functional significance of coronary lesions predicted by experienced interventionists and fractional flow reserve values measured by intracoronary pressure wire in 665 intermediate lesions (40%-70% diameter stenosis) in 587 patients. We determined which factors were independently associated with errors in prediction.

RESULTS

There was disagreement between the predicted fractional flow reserve value of ≤ 0.80 and the observed value in 30.1% of the lesions (overestimation: 11.3%; underestimation, 18.8%). Stent location in an artery other than the anterior descending artery or in a bifurcation was associated with overestimation. Male sex, severe calcification, and a greater myocardial territory distal to the lesion were significantly associated with the functional significance of the underestimated lesion.

CONCLUSIONS

Even when taking into account angiographic and clinical characteristics, there is a high rate of disagreement between visual estimation and direct measurement of intermediate coronary stenosis in relation to its functional significance. Specific angiographic and clinical characteristics are associated with an increased tendency to overestimate or underestimate the significance of lesions.

[Fractional flow reserve and instantaneous wave-free ratio for the physiological assessment of coronary artery stenosis in the catheterization laboratory: Practical tips]

In recent years, a large body of evidence has revealed the limitations of angiographic evaluation in determining the physiological significance of coronary stenosis, particularly when these are intermediate lesions. Percutaneous coronary interventions (PCI) guided by physiological assessment using fractional flow reserve (FFR) have been shown to reduce cardiovascular events when compared to angiography alone. Recently, another coronary physiologic parameter has been introduced: the "instantaneous wave-free ratio" (iFR). In this review, we will discuss the FFR, the iFR, and their use in the functional assessment of coronary stenosis in the cardiac catheterization laboratory. This review will cover theoretical aspects for non-interventional cardiologists, as well as practice points and common pitfalls related to coronary physiological assessment for interventional cardiologists.

Red Cell Distribution Width Can Predict the Significance of Angiographically Intermediate Coronary Lesions

OBJECTIVE

In the present study, the association between red cell distribution width (RDW) with functional significance of intermediate coronary artery lesions was investigated.

MATERIALS AND METHODS

Two hundred and forty-six consecutive patients, 168 males and 78 females, who underwent fractional flow reserve (FFR) measurement for angiographically intermediate coronary stenosis (40-70% in quantitative coronary analysis) in the left anterior descending coronary artery were enrolled into the study. The functional significance of intermediate coronary artery lesions was determined by FFR measurement. An FFR value <0.75 was defined as functionally significant. Venous blood samples were taken within 48 h before the FFR measurement, and RDW levels were determined by a Coulter LH Series hematology analyzer. Logistic regression analysis was used to examine the association between functional significance in FFR measurement and other variables.

RESULTS

Of the 246 patients, 62 (25.2%) exhibited significant functional stenosis (FFR <0.75) in the FFR measurement. The mean RDW level was significantly higher in patients with significant stenosis (14.19 ± 0.73 vs. 13.69 ± 0.77, p < 0.001). In stepwise multivariate logistic regression analysis, RDW (OR = 2.489, 95% CI = 1.631-3.799, p < 0.001) and male gender (OR = 2.826, 95% CI = 1.347-5.928, p = 0.006) were independent predictors of significant functional stenosis.

CONCLUSION

Increased RDW levels were associated with functional significance of angiographically intermediate coronary artery stenoses.

Fractional Flow Reserve Evaluation and Chronic Kidney Disease: Analysis From a Multicenter Italian Registry (the FREAK Study)

OBJECTIVES

To establish if the presence of chronic kidney disease (CKD) influences fractional flow reserve (FFR) value in patients with intermediate coronary stenosis.

BACKGROUND

FFR-guided coronary revascularization reduces cardiac adverse events in patients with coronary artery disease. CKD impairs microcirculation and increases cardiovascular risk. Whether CKD presence may limit FFR accuracy is unknown.

METHODS

We used data from a multicenter prospective registry enrolling 1.004 patients undergoing FFR evaluation for intermediate stenosis. We assessed the relationship between clinical and angiographic variables and FFR measurement. CKD was defined as CrCl value ≤45 ml/min. FFR value was considered potentially flow-limiting, and therefore positive, if ≤0.80. The index of microcirculatory resistance (IMR) was calculated in 20 patients stratified according CrCl value (single-center substudy).

RESULTS

FFR measurement was positive in 395 (39%) patients. Overall, 131 (13%) patients had CKD. Patients with CrCl ≤45 ml/min showed significantly higher FFR values as compared to the others (0.84 ± 0.07 vs. 0.81 ± 0.08, p < 0.001). Positive FFR occurrence was lower in patients with CrCl ≤45 ml/min (27% vs. 41%, p < 0.01). After multivariable analysis, diabetes (HR 1.07, 95%CI 1.008-1.13, p = 0.03), left anterior descending (HR 1.35, 95%CI 1.27-1.43, p < 0.001) and CrCl ≤45 ml/min (HR 0.92, 95%CI 0.87-0.97, p = 0.005) emerged as independent predictors of FFR measurement. Accordingly, IMR values were higher in patients with CrCl ≤45 ml/min (32 U [28245] vs. 16 U [11220], p < 0.01).

CONCLUSIONS

FFR and IMR measurements differ between CKD patients and those with normal renal function. Flow-limiting FFR is less frequent in patients with CrCl ≤45 ml/min. © 2015 Wiley Periodicals, Inc.

Fractional flow reserve: physiological basis, advantages and limitations, and potential gender differences

Fractional flow reserve (FFR) is a physiological index of the severity of a stenosis in an epicardial coronary artery, based on the pressure differential across the stenosis. Clinicians are increasingly relying on this method because it is independent of baseline flow, relatively simple, and cost effective. The accurate measurement of FFR is predicated on maximal hyperemia being achieved by pharmacological dilation of the downstream resistance vessels (arterioles). When the stenosis causes FFR to be impaired by > 20%, it is considered to be significant and to justify revascularization. A diminished hyperemic response due to microvascular dysfunction can lead to a false normal FFR value, and a misguided clinical decision. The blunted vasodilation could be the result of defects in the signaling pathways modulated (activated or inhibited) by the drug. This might involve a downregulation or reduced number of vascular receptors, endothelial impairment, or an increased activity of an opposing vasoconstricting mechanism, such as the coronary sympathetic nerves or endothelin. There are data to suggest that microvascular dysfunction is more prevalent in post-menopausal women, perhaps due to reduced estrogen levels. The current review discusses the historical background and physiological basis for FFR, its advantages and limitations, and the phenomenon of microvascular dysfunction and its impact on FFR measurements. The question of whether it is warranted to apply gender-specific guidelines in interpreting FFR measurements is addressed.

Diagnostic accuracy and discrimination of ischemia by fractional flow reserve CT using a clinical use rule: results from the Determination of Fractional Flow Reserve by Anatomic Computed Tomographic Angiography study

BACKGROUND

Fractional flow reserve (FFR) is the gold standard for determining lesion-specific ischemia. Computed FFRCT derived from coronary CT angiography (coronary CTA) correlates well with invasive FFR and accurately differentiates between ischemia-producing and nonischemic lesions. The diagnostic performance of FFRCT when applied in a clinically relevant way to all vessels ≥ 2 mm in diameter stratified by sex and age has not been previously examined.

METHODS

Two hundred fifty-two patients and 407 vessels underwent coronary CTA, FFRCT, invasive coronary angiography, and invasive FFR. FFRCT and FFR ≤ 0.80 were considered ischemic, whereas CT stenosis ≥ 50% was considered obstructive. The diagnostic performance of FFRCT was assessed following a prespecified clinical use rule which included all vessels ≥ 2 mm in diameter, not just those assessed by invasive FFR measurements. Stenoses <30% were assigned an FFR of 0.90, and stenoses >90% were assigned an FFR of 0.50. Diagnostic performance of FFRCT was stratified by vessel diameter, sex, and age.

RESULTS

By FFR, ischemia was identified in 129 of 252 patients (51%) and in 151 of 407 vessels (31%). Mean age (± standard deviation) was 62.9 ± 9 years, and women were older (65.5 vs 61.9 years; P = .003). Per-patient diagnostic accuracy (83% vs 72%; P < .005) and specificity (54% vs 82%, P < .001) improved significantly after application of the clinical use tool. These were significantly improved over standard coronary CTA values before application of the clinical use rule. Discriminatory power of FFRCT also increased compared with baseline (area under the receiver operating characteristics curve [AUC]: 0.93 vs 0.81, P < .001). Diagnostic performance improved in both sexes with no significant differences between the sexes (AUC: 0.93 vs 0.90, P = .43). There were no differences in the discrimination of FFRCT after application of the clinical use rule when stratified by age ≥ 65 or <65 years (AUC: 0.95 vs 0.90, P = .10).

CONCLUSIONS

The diagnostic accuracy and discriminatory power of FFRCT improve significantly after the application of a clinical use rule which includes all clinically relevant vessels >2 mm in diameter. FFRCT has similar diagnostic accuracy and discriminatory power for ischemia detection in men and women irrespective of age using a cut point of 65 years.