Sex-related differences in fractional flow reserve-guided treatment

The role of gender in resting full-cycle ratio (RFR) guided coronary revascularization

BACKGROUND

Gender-based differences in clinical outcomes of patients undergoing fractional flow reserved (FFR) guided coronary revascularization is well documented. This study aimed to compare resting full-cycle ratio (RFR) values between men and women and whether this translated into difference in clinical outcomes in patients who underwent RFR-guided coronary revascularization.

METHODS

This was a retrospective single-centre study of consecutive patients who underwent RFR-guided revascularization for coronary lesions with intermediate degree of stenosis. The primary endpoint was a composite of all-cause mortality, myocardial infarction (MI), unplanned revascularization, and unstable angina requiring hospital admission at one year.

RESULTS

In 373 consecutive patients (510 lesions, 26% women) there was no statistically significant difference in RFR value between men and women (0.90 ± 10 versus 0.90 ± 11, P = 0.95). There was no statistically significant difference between men and women in the primary endpoint, even after adjustment to the imbalance between the two groups [3.7% vs. 3.0%; HR 1.43, 95% CI (0.46 to 4.43), P = 0.54]; or its individual components of death (1.1% vs 0.8%, P = 0.76), MI (1.9% vs 0.8%, P = 0.38) or unplanned revascularization, including unstable angina admissions (2.6% vs 2.3%, P = 0.82). The comparable clinical outcomes were consistent across all different subgroups, including clinical presentation, diabetes status, left ventricle systolic function, kidney function, and the interrogated coronary artery.

CONCLUSION

Our study suggests no significant gender-based difference in the value of RFR or 1-year clinical outcomes in patients undergoing resting physiology guided coronary revascularization.

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.

Vessel-Specific Outcomes of Deferred Revascularization Following Negative Fractional Flow Reserve

Variations in myocardial supply area and hydrostatic pressure gradients result in greater likelihood of positive fractional flow reserve (FFR) in the left anterior descending (LAD) compared with the circumflex (Cx) and right coronary artery (RCA). However, the same FFR threshold for deferral of revascularization is applied to all arteries, without evidence that this results in equivalent outcomes. We assessed vessel-specific outcomes of deferred revascularization for the 3 major coronary arteries based on FFR > 0.8. In this retrospective study, data were obtained on consecutive patients who underwent indicated FFR assessment across 2 tertiary institutions. Patients with deferred revascularization were followed for 36 months for the primary end point of vessel-specific target lesion failure (TLF). Of 1,916 major coronary arteries (1,579 patients), the odds ratio of positive FFR was highest in the LAD (odds ratio 3.36, p <0.001). In total, 867 vessels (733 patients) with FFR > 0.8 had complete 3-year medical record follow-ups. The TLF rate for deferred vessels was 10.21%, 11.52%, and 10.96% for the LAD, Cx, and RCA respectively. In a multivariate analysis, there was no significant difference in the odds of TLF for the 0.84 (0.53 to 1.33, p = 0.459), 1.17 (0.68 to 2.01, p = 0.582), and 1.11 (0.62 to 2.00, p = 0.715) in the LAD, Cx, and RCA, respectively. In a multivariate analysis, diabetes mellitus was the only baseline characteristic significantly associated at risk of TLF (1.43 [1.01 to 2.02], p = 0.043). In conclusion, despite greater likelihood of positive FFR in the LAD, the FFR threshold for deferred revascularization resulted in equivalent outcomes in all 3 major coronary arteries, and patients with diabetes mellitus may represent a group that requires aggressive surveillance and risk factor modification after deferred revascularization.

Multimodality OCT, IVUS and FFR evaluation of coronary intermediate grade lesions in women vs. men

Background

The pathophysiology of atherosclerotic plaque formation and its vulnerability seem to differ between genders due to contrasting risk profiles and sex hormones, however this process is still insufficiently understood. The aim of the study was to compare the differences between sexes regarding the optical coherence tomography (OCT), intravascular ultrasound (IVUS) and fractional flow reserve (FFR)-derived coronary plaque indices.

Methods

In this single-center multimodality imaging study patients with intermediate grade coronary stenoses identified in coronary angiogram (CAG) were evaluated using OCT, IVUS and FFR. Stenoses were considered significant when the FFR value was ≤0.8. Minimal lumen area (MLA), was analyzed by OCT in addition to plaque stratification into fibrotic, calcific, lipidic and thin-cap fibroatheroma (TCFA). IVUS was used for evaluation of lumen-, plaque- and vessel volume, as well as plaque burden.

Results

A total of 112 patients (88 men and 24 women) with chronic coronary syndromes (CCS), who underwent CAG were enrolled. No significant differences in baseline characteristics were present between the study groups. The mean FFR was 0.76 (0.73-0.86) in women and 0.78 ± 0.12 in men (p = 0.695). OCT evaluation showed a higher prevalence of calcific plaques among women than men p = 0.002 whereas lipid plaques were more frequent in men (p = 0.04). No significant differences regarding minimal lumen diameter and minimal lumen area were found between the sexes. In IVUS analysis women presented with significantly smaller vessel area, plaque area, plaque volume, vessel volume (11.1 ± 3.3 mm² vs. 15.0 ± 4.6 mm² p = 0.001, 6.04 ± 1.7 mm² vs. 9.24 ± 2.89 mm² p < 0.001, 59.8 ± 35.2 mm³ vs. 96.3 (52.5-159.1) mm³ p = 0.005, 106.9 ± 59.8 mm³ vs. 153.3 (103-253.4) mm³ p = 0.015 respectively). At MLA site plaque burden was significantly greater for men than women (61.50 ± 7.7% vs. 55.5 ± 8.0% p = 0.005). Survival did not differ significantly between women and men (94.6 ± 41.9 months and 103.51 ± 36.7 months respectively; p = 0.187).

Conclusion

The presented study did not demonstrate significant differences in FFR values between women and men, yet a higher prevalence of calcific plaques by OCT and lower plaque burden at the MLA site by IVUS was found in women vs. men.

Sex-based difference in fractional flow reserve and its impact on clinical outcomes

BACKGROUND

Obesity is a real public health problem and is of growing concern. People are resorting to surgical or endoscopic means to fight against overweight and obesity. In recent years, there has been a marked increase in the use of these means and in particular the insertion of a gastric balloon which seems to present less risk than surgical methods. Renal complications from intragastric balloon placement are extremely rare. We report here the case of compression of the left renal vein revealed by lumbar pain and hematuria in an overweight 39-year-old woman who benefited from the balloon gastric placement one month before symptoms. The scanner made the diagnosis and showed a good evolution after the withdrawal of the balloon.

METHODS

This was a prespecified and retrospective analysis of all consecutive patients who underwent FFR assessment for intermediate coronary lesions between January 2014 and December 2015. The primary endpoint was defined as the 1-year composite of cardiac death, vessel-related myocardial infarction, and clinically-driven target vessel revascularization.

RESULTS

In 1554 lesions (23% in women), FFR was lower in men [0.83 ±0.09 vs 0.85 ±0.08, P = .004] driven by LAD values (for LAD P < .001, LCx or RCA P> .40). In proximal lesions (PLs), FFR was lower in men [0.83 ±0.10 vs 0.85 ±0.08, P = .004] with comparable values in non-PLs [0.84 ±0.09 vs 0.85 ±0.08, P = .36]. In PLs, the primary endpoint was higher in women [HR_(adjusted) 3.18 (1.08-9.37), P = .035] with comparable outcomes in non-PLs (P = .032 for interaction). In deferred lesions, the primary endpoint was higher in women [HR_(adjusted) 2.73 (1.10-6.74), P = .03] with no differences in revascularized lesions across sex (P = .02 for interaction). Results were consistent when using propensity score matching analysis.

CONCLUSIONS

There is a sex-based difference in FFR, particularly in stenoses subtending large myocardium, and more evident in deferred lesions.

Effect of Sex Difference on Discordance Between Instantaneous Wave-Free Ratio and Fractional Flow Reserve

BACKGROUND

Physiology-guided percutaneous coronary intervention (PCI) has demonstrated to improve clinical outcomes. Previous trials showed the agreement between iFR and FFR is approximately 80%, however the details of discordance pattern remain to be elucidated.

METHODS

We retrospectively reviewed 1024 consecutive intermediate stenotic lesions for which functional evaluation using both iFR and FFR were performed between January 2015 and June 2016. The lesions were classified into 4 groups according to iFR and FFR concordance [(iFR+/FFR+) and (iFR-/FFR-)] or discordance [(iFR+/FFR-) and (iFR-/FFR+)].

RESULTS

Our study evaluated 451 lesions, 264 lesions (58.5%) from men and 187 lesions (41.5%) from women. iFR was similar between women and men, however FFR was significantly higher in women than men. The rate of discordance between iFR and FFR was 21.3% (iFR+/FFR- 12.4% and iFR-/FFR+ 8.9%) in overall cohort. The prevalence of overall concordance and discordance were similar between men and women, however iFR+/FFR- discordance was significantly higher in women (17.1% vs. 9.1%) whereas iFR-/FFR+ discordance was significantly higher in men (11.3% vs. 4.8%). In multivariable analysis, female sex and older age were significantly associated with iFR+/FFR- discordance (odds ratio 1.88 and 1.48, respectively). Conversely, younger age, higher stenosis, and concomitant chronic total occlusion were independent predictors for iFR-/FFR+ discordance (odds ratio 0.67, 1.82, and 4.32, respectively).

CONCLUSIONS

Despite similar prevalence of overall concordance and discordance between men and women, iFR+/FFR- discordance was higher in women and iFR-/FFR+ discordance was higher in men. Multivariable analysis showed female sex to be independent predictor of iFR+/FFR- discordance.

Sex Differences in Long-Term Outcomes in Patients With Deferred Revascularization Following Fractional Flow Reserve Assessment: International Collaboration Registry of Comprehensive Physiologic Evaluation

Background

Sex‐specific differences may influence prognosis after deferred revascularization following fractional flow reserve (FFR) measurement. This study sought to investigate the sex differences in long‐term prognosis of patients with deferred revascularization following FFR assessment.

Methods and Results

A total of 879 patients (879 vessels) with deferred revascularization with FFR >0.75 who underwent FFR and coronary flow reserve measurements were enrolled from 3 countries (Korea, Japan, and Spain). Long‐term outcomes were assessed in 649 men and 230 women by the patient‐oriented composite outcome (POCO, a composite of any death, any myocardial infarction, and any revascularization). We applied inverse‐probability weighting based on propensity scores to account for differences at baseline between women and men (age, hyperlipidemia, diabetes mellitus, diameter stenosis, lesion length, multivessel disease, FFR, coronary flow reserve. The median follow‐up duration was 1855 days (745–1855 days). Median FFR values were 0.88 (0.83–0.93) in men and 0.89 (0.85–0.94) in women, respectively. The occurrences of POCO were significantly high in men compared with that in women (10.5% versus 4.2%, P=0.007). Kaplan–Meier analysis revealed that women had a significantly lower risk of POCO (χ²=7.2, P=0.007). Multivariate COX proportional hazards regression analysis revealed that age, male, diabetes mellitus, diameter stenosis, lesion length, and coronary flow reserve were independent predictors of POCO. After applying IPW, the hazard ratio of males for POCO was 2.07 (95% CI, 1.07–4.04, P=0.032).

Conclusions

This large multinational study reveals that long‐term outcome differs between women and men in favor of women after FFR‐guided revascularization deferral.

Clinical Trial Registration

URL: http://www.ClinicalTrials.gov. Unique identifier: NCT02186093.

Clinical and angiographic factors predicting fractional flow reserve and explaining the visual-functional mismatch in patients with intermediate coronary artery stenosis

BACKGROUND

Visual-functional mismatch between coronary angiography and fractional flow reserve (FFR) has been reported, and the underlying reason remains poorly understood. Therefore, the relationship between angiographic measurements and FFR was evaluated, and predictors for FFR in intermediate coronary artery stenosis were determined.

METHODS

Consecutive 314 patients (405 lesions) with a lesion of 30-80% angiographic diameter stenosis who underwent invasive FFR were recruited. The myocardial area supplied by the coronary artery distal to the stenosis was evaluated using a modified version of the Bypass Angioplasty Revascularization Investigation (BARI) score. Participants underwent follow-up, and major cardiovascular events (MACE), including all-cause death, myocardial infarction (MI), and unplanned revascularization were recorded.

RESULTS

Although % diameter stenosis was correlated with FFR (R = 0.279, P < 0.001), diameter stenosis-FFR mismatch was observed in 37.8% of the lesions. Although FFR values were not associated with clinical factors, such as age, sex, and comorbidities, it was correlated with minimal lumen diameter (MLD), diffuse lesion, presence of proximal lesion, and BARI score. In addition, the lesions in left anterior descending (LAD) coronary artery showed low FFR values compared with those in the left circumflex coronary artery or right coronary artery. In multivariate logistic analysis, MLD (β coefficient = 0.330), diffuse lesion (β coefficient = -0.266), proximal lesion (β coefficient = -0.144), BARI score (β coefficient = -0.219), and LAD lesion (β coefficient = -0.293) were all independent predictors for FFR value. The estimated FFR value based on these factors showed smaller mismatch and higher sensitivity. No difference was observed in the event rates for MACE and MI or revascularization between the FFR-guided and estimated FFR-guided strategies.

CONCLUSIONS

MLD, diffuse lesion, proximal lesion, BARI score, and lesion vessel were independent predictors for FFR in intermediate coronary stenosis. Not only the extent of local lesion stenosis but also the amount of myocardial supply and the lesion location may determine the physiological significance and explain the visual-functional mismatch. The estimation of FFR by these factors may be useful in clinical practice.

Are we ready for a gender-specific approach in interventional cardiology?

Gender differences in the pathophysiology of atherosclerosis, cardiovascular risk factors, and diagnosis of coronary artery disease and valvular heart disease are well known. Such differences have also been outlined in the management and outcomes after acute coronary syndromes and valvular repair. Regarding the atherosclerotic process, pathological experimental studies suggest that plaque composition and burden may differ by gender. Female gender is associated with worse outcomes in the case of ischemic heart disease and, compared with men, women are less likely to undergo interventional cardiac procedures and sustain worse outcomes. In the setting of valvular heart disease (VHD), transcatheter aortic valve implantation (TAVI) and percutaneous edge-to-edge mitral valve repair are now well-established procedures with high success rates. In women with moderate to severe aortic stenosis, subgroup analyses in TAVI trials have demonstrated gender-related differences suggesting female gender as beneficial in terms of short-, mid-, and long-term outcomes. Similarly, several studies reported different procedural challenges and outcomes in males and females following surgical and percutaneous mitral valve repair. These diverse findings emphasize the necessity to provide gender-specific analyses of interventional methods. This review highlights gender differences in the epidemiology, pathophysiology, treatment options and clinical outcomes of the conditions mentioned above.

Coronary artery disease in post-menopausal women: are there appropriate means of assessment?

The recognition of sex differences in cardiovascular disease, particularly the manifestations of coronary artery disease (CAD) in post-menopausal women, has introduced new challenges in not only understanding disease mechanisms but also identifying appropriate clinical means of assessing the efficacy of management strategies. For example, the majority of treatment algorithms for CAD are derived from the study of males, focus on epicardial stenoses, and inadequately account for the small intramyocardial vessel disease in women. However, newer investigational modalities, including stress perfusion cardiac magnetic resonance imaging and positron emission tomography are providing enhanced diagnostic accuracy and prognostication for women with microvascular disease. Moreover, these investigations may soon be complemented by simpler screening tools such as retinal vasculature imaging, as well as novel biomarkers (e.g. heat shock protein 27). Hence, it is vital that robust, sex-specific cardiovascular imaging modalities and biomarkers continue to be developed and are incorporated into practice guidelines that are used to manage women with CAD, as well as gauge the efficacy of any new treatment modalities. This review provides an overview of some of the sex differences in CAD and highlights emerging advances in the investigation of CAD in post-menopausal women.

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.

Unsettled Issues and Future Directions for Research on Cardiovascular Diseases in Women

Biological sex (being female or male) significantly influences the course of disease. This simple fact must be considered in all cardiovascular diagnosis and therapy. However, major gaps in knowledge about and awareness of cardiovascular disease in women still impede the implementation of sex-specific strategies. Among the gaps are a lack of understanding of the pathophysiology of women-biased coronary artery disease syndromes (spasms, dissections, Takotsubo syndrome), sex differences in cardiomyopathies and heart failure, a higher prevalence of cardiomyopathies with sarcomeric mutations in men, a higher prevalence of heart failure with preserved ejection fraction in women, and sex-specific disease mechanisms, as well as sex differences in sudden cardiac arrest and long QT syndrome. Basic research strategies must do more to include female-specific aspects of disease such as the genetic imbalance of 2 versus one X chromosome and the effects of sex hormones. Drug therapy in women also needs more attention. Furthermore, pregnancy-associated cardiovascular disease must be considered a potential risk factor in women, including pregnancy-related coronary artery dissection, preeclampsia, and peripartum cardiomyopathy. Finally, the sociocultural dimension of gender should be included in research efforts. The organization of gender medicine must be established as a cross-sectional discipline but also as a centered structure with its own research resources, methods, and questions.

Fractional flow reserve: a clinical perspective

Fractional flow reserve (FFR) is a reference invasive diagnostic test to assess the physiological significance of an epicardial coronary artery stenosis. FFR-guided percutaneous coronary intervention in stable coronary artery disease has been assessed in three seminal clinical trials and the indications for FFR assessment are expanding into other clinical scenarios. In this article we review the theoretical, experimental and clinical basis for FFR measurement. We place FFR measurement in the context of the comprehensive invasive assessment of coronary physiology in patients presenting with known or suspected angina pectoris in daily clinical practice, and review the recent developments in FFR assessment.

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.

[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.

Relation between fractional flow reserve value of coronary lesions with deferred revascularization and cardiovascular outcomes in non-diabetic and diabetic patients

BACKGROUND

FFR of deferred PCI lesions can predict future cardiovascular events. However, the prognostic utility of FFR remains unclear in diabetic patients in view of the potential impact of the diffuse nature of vascular disease process. We aimed to study the relation between fractional flow reserve (FFR) values and long-term outcomes of diabetic and non-diabetic patients with deferred percutaneous coronary intervention (PCI).

METHODS

Patients with FFR assessment and deferred PCI (n=630) were enrolled and stratified according to diabetes mellitus (DM) status and FFR values. Patients were followed over a median of 39months. Cox proportional hazard regression models were used to analyze the association between clinical endpoints and clinical factors such as DM and FFR.

RESULTS

In non-diabetics (n=450), higher FFR values were associated with less cardiovascular events (hazard ratio (HR) for death and myocardial infarction (MI) [95% confidence interval (CI)], 0.61[0.44 to 0.86] per 0.1 increase in FFR, p=0.007; HR for revascularization [95%CI], 0.66[0.49 to 0.9] per 0.1 increase in FFR, p=0.006). In diabetics (n=180), there was no difference in death and MI across the range of FFR values. Among those patients with an FFR >0.85, diabetics had a more than two-fold higher risk of death and MI than non-diabetics (HR [95% CI], 2.20 [1.19 to 4.01], p=0.015).

CONCLUSION

Among non-diabetic patients with deferred PCI, a higher FFR was associated with lower rates of death, MI and revascularization. On the contrary in diabetic patients with deferred revascularization, FFR was not able to differentiate the risk of cardiovascular events.

Comparison of Ticagrelor Versus Thienopyridine Loading Effect on Fractional Flow Reserve in Patients With Coronary Artery Disease

Ticagrelor loading dose (LD) increases adenosine plasma levels, which might interfere with fractional flow reserve (FFR) assessment because the latter is based on adenosine-induced hyperemia. In a prospective study, consecutive patients who underwent coronary angiography with at least 1 de novo stenosis >50% and <90% in severity amenable to intervention underwent FFR assessment using intravenous adenosine 140 μg/kg/min for 3 minutes. Patients were subsequently randomized to either ticagrelor 180 mg (n = 38) or control thienopyridine (n = 38) (prasugrel 60 mg [n = 28] or clopidogrel 600 mg [n = 10]), followed by a second FFR assessment of the target lesion 2 hours after drug. Pre-drug, steady hyperemia FFR (sFFR, median, first to third quartiles) was 0.82 (0.75 to 0.88) and 0.81 (0.75 to 0.88), p = 0.9, whereas post-drug, 0.82 (0.72 to 0.87) and 0.79 (0.73 to 0.86), p = 0.5, in thienopyridine and ticagrelor-treated patients, respectively. The primary end point of percent relative change in sFFR between pre- and post-drug periods was greater in ticagrelor- than thienopyridine-treated patients, -1.24 (-5.54 to 0.0) versus -0.51 (-3.68 to 3.21), p = 0.03, respectively. Absolute change in sFFR between pre- and post-drug periods was marginally higher in ticagrelor- than thienopyridine-treated patients -0.01 (-0.04 to 0.0) versus -0.005 (-0.03 to 0.02), p = 0.048, respectively. Reclassification of treatment decision at the sFFR ≤ 0.80 cutoff post-drug occurred in 6 (15.8%) versus 5 (13.2%) of ticagrelor- and thienopyridine-treated patients, respectively. In conclusion, after ticagrelor LD, an absolute and relative reduction in sFFR compared with thienopyridine LD is observed. Administration of ticagrelor should be considered as a potential source, albeit minor, of FFR variability.

Fractional flow reserve-guided management in stable coronary disease and acute myocardial infarction: recent developments

Coronary artery disease (CAD) is a leading global cause of morbidity and mortality, and improvements in the diagnosis and treatment of CAD can reduce the health and economic burden of this condition. Fractional flow reserve (FFR) is an evidence-based diagnostic test of the physiological significance of a coronary artery stenosis. Fractional flow reserve is a pressure-derived index of the maximal achievable myocardial blood flow in the presence of an epicardial coronary stenosis as a ratio to maximum achievable flow if that artery were normal. When compared with standard angiography-guided management, FFR disclosure is impactful on the decision for revascularization and clinical outcomes. In this article, we review recent developments with FFR in patients with stable CAD and recent myocardial infarction. Specifically, we review novel developments in our understanding of CAD pathophysiology, diagnostic applications, prognostic studies, clinical trials, and clinical guidelines.

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.