Impact of accuracy of fractional flow reserve to reduction of microvascular resistance after intracoronary adenosine in patients with angina pectoris or non-ST-segment elevation myocardial infarction

Fractional flow reserve in acute coronary syndrome: a meta-analysis and systematic review

Background

The utility of fractional flow reserve (FFR) to guide revascularisation in the management of acute coronary syndrome (ACS) remains unclear.

Objective

This study aims to compare the clinical outcomes of patients following FFR-guided revascularisation for either ACS or stable angina (SA) and in particular focuses on the outcome of those with deferred revascularisation after FFR.

Methods

A meta-analysis of existing literature was performed. Outcomes including the rate of major adverse cardiovascular events (MACE), recurrent myocardial infarction (MI), mortality and unplanned revascularisation were analysed.

Results

A review of 937 records yielded 9 studies comparing 5457 patients, which were included in the analyses. Patients with ACS had a higher rate of recurrent MI (OR 1.81, p=0.02) and a strong trend towards more MACE and all-cause mortality compared with patients with SA when treated by an FFR-guided revascularisation strategy. Deferral of invasive therapy on the basis of FFR led to a higher rate of MACE (17.6% vs 7.3 %; p=0.004), recurrent MI (5.3% vs 1.5%, p=0.001) and target vessel revascularisation (16.4% vs 5.6 %; p=0.02) in patients with ACS, and a strong trend towards a higher cardiovascular mortality at follow-up when compared with patients with SA.

Conclusion

The event rate in patients with ACS is much higher than SA despite following an FFR-guided revascularisation strategy. Deferring revascularisation does not appear to be as safe for ACS as it is for SA using contemporary FFR cut-offs validated in SA. Refinement of the therapeutic strategy for patients with ACS with multivessel disease is needed to redress the balance.

Impact of Routine Fractional Flow Reserve on Management Decision and 1-Year Clinical Outcome of Patients With Acute Coronary Syndromes: PRIME-FFR (Insights From the POST-IT [Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease] and R3F [French FFR Registry] Integrated Multicenter Registries - Implementation of FFR [Fractional Flow Reserve] in Routine Practice)

BACKGROUND

Fractional flow reserve (FFR) is not firmly established as a guide to treatment in patients with acute coronary syndromes (ACS). Primary goals were to evaluate the impact of integrating FFR on management decisions and on clinical outcome of patients with ACS undergoing coronary angiography, as compared with patients with stable coronary artery disease.

METHODS AND RESULTS

R3F (French FFR Registry) and POST-IT (Portuguese Study on the Evaluation of FFR-Guided Treatment of Coronary Disease), sharing a common design, were pooled as PRIME-FFR (Insights From the POST-IT and R3F Integrated Multicenter Registries - Implementation of FFR in Routine Practice). Investigators prospectively defined management strategy based on angiography before performing FFR. Final decision after FFR and 1-year clinical outcome were recorded. From 1983 patients, in whom FFR was prospectively used to guide treatment, 533 sustained ACS (excluding acute ST-segment-elevation myocardial infarction). In ACS, FFR was performed in 1.4 lesions per patient, mostly in left anterior descending (58%), with a mean percent stenosis of 58±12% and a mean FFR of 0.82±0.09. In patients with ACS, reclassification by FFR was high and similar to those with non-ACS (38% versus 39%; P=NS). The pattern of reclassification was different, however, with less patients with ACS reclassified from revascularization to medical treatment compared with those with non-ACS (P=0.01). In ACS, 1-year outcome of patients reclassified based on FFR (FFR against angiography) was as good as that of nonreclassified patients (FFR concordant with angiography), with no difference in major cardiovascular event (8.0% versus 11.6%; P=0.20) or symptoms (92.3% versus 94.8% angina free; P=0.25). Moreover, FFR-based deferral to medical treatment was as safe in patients with ACS as in patients with non-ACS (major cardiovascular event, 8.0% versus 8.5%; P=0.83; revascularization, 3.8% versus 5.9%; P=0.24; and freedom from angina, 93.6% versus 90.2%; P=0.35). These findings were confirmed in ACS explored at the culprit lesion. In patients (6%) in whom the information derived from FFR was disregarded, a dire outcome was observed.

CONCLUSIONS

Routine integration of FFR into the decision-making process of ACS patients with obstructive coronary artery disease is associated with a high reclassification rate of treatment (38%). A management strategy guided by FFR, divergent from that suggested by angiography, including revascularization deferral, is safe in ACS.

Evaluation of intermediate coronary stenoses in acute coronary syndromes using pressure guidewire

Fractional flow reserve (FFR) is increasingly used to guide myocardial revascularisation. However, supporting evidence regarding its use originates from studies that have enrolled mainly patients with stable angina, while patients with acute coronary syndromes (ACS) have not been included. Notably, multifactorial microvascular dysfunction and an increased sympathetic tone in patients with ACS may lead to blunted response to adenosine and false-negative results of FFR due to submaximal hyperaemia. This may raise the possibility of deferring treatment of stenosis that instead would have needed dilatation, thus leaving a residual risk of preventable cardiac events. In this literature review, we aim at summarising laboratory and clinical investigations concerning the use of FFR in culprit and non-culprit lesions in ACS. Furthermore, we will report recent data on instantaneous wave-free ratio, an adenosine-free index of functional stenosis severity, in stable coronary artery disease and in patients with ACS.

Prognostic role of multiple biomarkers in stable patients undergoing fractional flow reserve-guided coronary angioplasty

AIMS

Fractional flow reserve (FFR)-guided percutaneous coronary intervention (PCI), along with optimal medical therapy, improves clinical outcome by targeting ischemia-inducing stenosis. Yet, plaque progression or stent failure may cause recurring cardiac events. We assessed the potential prognostic role of different inflammatory biomarkers, known to be associated with plaque progression or stent failure, in patients undergoing FFR-guided PCI.

METHODS

We prospectively enrolled 169 stable angina patients with intermediate coronary stenosis at angiography undergoing FFR-guided PCI. PCI was performed if FFR was 0.80 or less, deferred if FFR was more than 0.80. Serum baseline levels of high-sensitivity C-reactive protein (hs-CRP), eosinophil cationic protein (ECP), cystatin-C (Cys-C), and thromboxane A2 (TXA2) were assessed. Rate of major adverse cardiovascular events (MACE), defined as a composite of cardiovascular death, recurrent myocardial infarction, and target vessel revascularization (TVR), was evaluated.

RESULTS

PCI was performed in 78 patients (46%) (mean age 69 ± 10 years, men 73%) and deferred in 91 patients (54%) (mean age 64 ± 11 years, men 53%). Mean clinical follow-up was 31 ± 11 months. Within the PCI group, patients with MACE (n = 14 [18%]) had significantly higher ECP levels than those without (14.4 [9.3-19.5] vs. 4.9 [2.8-10.9] mg/l, P < 0.001), and ECP was a significant predictor of MACE (hazard ratio: 1.05, 95% confidence interval [1.01-1.09], P = 0.021). Within the deferred group, patients with MACE (n = 8 [9%]) had significantly higher CRP levels than those without (15 [6.5-31.9] vs. 1.6 [0.9-2.9] mg/l, P < 0.001) and CRP was a significant predictor of MACE (hazard ratio: 1.04, 95% confidence interval [1.01-1.07], P = 0.015). Cys-C and TXA2 were not significantly different between the two groups.

CONCLUSION

Assessing inflammatory biomarkers allows the identification of patients remaining at residual higher risk of MACE after FFR-guided PCI.

Efficacy of Adenosine in Patients With Acute Myocardial Infarction Undergoing Primary Percutaneous Coronary Intervention: A PRISMA-Compliant Meta-Analysis

Whether adenosine offers cardioprotective effects when used as an adjunctive therapy for patients with acute myocardial infarction (AMI) undergoing primary percutaneous coronary intervention (PCI) remains controversial.To evaluate, via meta-analysis, the efficacy of adenosine in patients with AMI undergoing PCI.Randomized controlled trials (RCTs) published in Medline, Embase, and the Cochrane Central Register of Controlled Trials.RCTs of patients with AMI undergoing primary PCI, comparing adenosine treatment and placebo groups and reporting mortality, thrombolysis in myocardial infarction (TIMI) flow grade, myocardial blush grade (MBG), re-infarction, left-ventricular ejection fraction (LVEF), ST-segment elevation resolution (STR), recurrent angina, or heart failure (HF).Risk of bias was assessed by the Cochrane guidelines and publication bias by Egger's test. For studies reported in multiple publications, the most complete publication was used. Arms using different dosing schedules were merged. Mean differences (MDs) or risk ratios (RRs) were determined.Data were extracted from 15 RCTs involving 1736 patients. Compared with placebo, adenosine therapy was associated with fewer occurrences of heart failure (RR: 0.65, 95% confidence interval [CI]: 0.43-0.97, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.03) and no-reflow (TIMI flow grade <3, RR: 0.62, 95% CI: 0.45-0.85, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.003; MBG[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0-1, RR: 0.81; 95% CI: 0.67-0.98, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.03), more occurrences of STR (RR: 1.19, 95% CI: 1.07-1.31, P[REPLACEMENT CHARACTER]<[REPLACEMENT CHARACTER]0.00001), but no overall improvement of LVEF (MD: 2.29, 95% CI: -0.09 to 4.67, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.06). Adenosine improved LVEF in the intravenous subgroup and the regular-dose intracoronary (IC) subgroup (0.24-2.25[REPLACEMENT CHARACTER]mg) compared with placebo (MD: 2.68, 95% CI: 0.66-4.70, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.009). Adenosine was associated with a poorer LVEF in the high-dose (4-6[REPLACEMENT CHARACTER]mg) IC subgroup (MD: -2.40; 95% CI: -4.72 to -0.09, P[REPLACEMENT CHARACTER]=[REPLACEMENT CHARACTER]0.04). There was no significant evidence that adenosine reduced rates of all-cause mortality, cardiovascular mortality or re-infarction after PCI.Adenosine dosage and administration routes, baseline profiles, and endpoints differed among included RCTs. Performance, publication, and reporting biases remain possible.Adenosine therapy appears to improve several outcomes in patients with AMI after PCI, but there is no evidence that adenosine can reduce mortality rates.

Fundamentals in clinical coronary physiology: why coronary flow is more important than coronary pressure

Wide attention for the appropriateness of coronary stenting in stable ischaemic heart disease (IHD) has increased interest in coronary physiology to guide decision making. For many, coronary physiology equals the measurement of coronary pressure to calculate the fractional flow reserve (FFR). While accumulating evidence supports the contention that FFR-guided revascularization is superior to revascularization based on coronary angiography, it is frequently overlooked that FFR is a coronary pressure-derived estimate of coronary flow impairment. It is not the same as the direct measures of coronary flow from which it was derived, and which are critical determinants of myocardial ischaemia. This review describes why coronary flow is physiologically and clinically more important than coronary pressure, details the resulting limitations and clinical consequences of FFR-guided clinical decision making, describes the scientific consequences of using FFR as a gold standard reference test, and discusses the potential of coronary flow to improve risk stratification and decision making in IHD.