ABC | Volume 111, Nº4, Octuber 2018

Original Article Martins ACS Fractional flow reserve-guided strategy Arq Bras Cardiol. 2018; 111(4):542-550 Table 2 – Clinical outcomes of ACS and non-ACS patients with deferred lesion treatment based on fractional flow reserve Author Year Patients [FFR > cutoff] * Mortality CV Mortality Myocardial infarction Target lesion revascularization Target vessel revascularization Potvin JM et al 9 2006 ACS → 124 Non-ACS → 61 NR ACS → 0 Non-ACS → 1 ACS → 2 Non-ACS → 1 NR ACS → 11 Non-ACS → 7 Fischer J. et al 8 2006 ACS → 35 Non-ACS → 76 ACS → 3 Non-ACS → 5 ACS → 2 Non-ACS → 1 ACS → 1 Non-ACS → 1 NR ACS → 6 Non-ACS → 7 Sels et al 24 2011 NR ** ACS → 12 Non-ACS → 20 NR Non-ACS → 36 Non-ACS → 44 NR ACS → 45 Non-ACS → 72 Mehta et al 25 2015 ACS → 334 Non-ACS → 340 NR ACS → 23 Non-ACS → 8 ACS → 47 Non-ACS → 26 ACS → 78 Non-ACS → 66 NR Hakeem A et al 34 2016 ACS → 206 Non-ACS → 370 NR ACS → 9 Non-ACS → 30 ACS → 16 Non-ACS → 11 ACS → 36 Non-ACS → 29 ACS → 15 Non-ACS → 14 Van Belle et al 38 2017 ACS → 237 Non-ACS → 721 ACS → 10 Non-ACS → 17 NR ACS → 3 Non-ACS → 7 NR NR *** ACS → 9; *** Non-ACS → 42] Lee JM et al 37 2017 ACS → 301 Non-ACS 1295 NR ACS → 3 Non-ACS → 5 ACS → 2 Non-ACS → 4 ACS → 8 Non-ACS → 10 ACS: acute coronary syndrome; CV: cardiovascular; NR: not reported; *Cut-off values varied from 0.75 to 0.80 among the studies; ** Sels et al. 24 evaluated whether there is a difference in benefit of fractional flow reserve (FFR) guidance for percutaneous coronary intervention (PCI) in multivessel coronary disease in patients with acute coronary syndrome (ACS) vs. non-ACS without discriminating those patients with FFR > 0.80; *** Target-vessel revascularization was not specified. MVD patients; the rate of major adverse cardiac events (defined as cardiac mortality or hospitalization for MI or heart failure) was 7.5% in patients with deferred PCI based on FFR and 0% in those deferred PCI based on angiography. 13 The aim of this analysis was not to evaluate FFR-guided decisions per-lesion level, but rather to focus on the relevance of FFR-guided decision per-patient level, considering that patients with ACS frequently have more than 1 lesion suitable for revascularization and the identification of the culprit lesion is not always straightforward. Undoubtedly, patients with MVD have worse outcomes than patients who present with single vessel disease. The natural history of patients who are revascularized in an acute setting is known to differ from those who are revascularized in a stable setting. 33 For example, the probability of malignant dysrhythmias is significantly more common in acute patients and is an important cause of mortality. 33 This systematic review and meta-analysis summarizes all published studies that assessed and compared clinical outcomes in which revascularization decisions were based on FFR in ACS versus non-ACS setting. Among the clinical endpoints evaluated, only the RR of MI was significantly higher in patients with ACS. The higher risk of subsequent MI found in this study and by several authors is explained by the different pathophysiology of ACS versus stable coronary disease. 34-36 Hakeem et al. compared the outcomes in NSTEMI patients who did not undergo PCI of any lesion on the basis of FFR to those in a similar group of non-ACS patients. After an average 3.4-years follow-up, using propensity score matching, the MI and TVR rates were higher in NSTEMI patients than in non-ACS patients (25% vs. 12%, respectively; p < 0.0001). 34 Similar results were reported recently by Lee et al. in non-ACS patients. 37 When MI injury (defined as any MI attributable to a deferred revascularization based on the index FFR) was specifically evaluated, deferring treatment of lesions based on FFR did not differ significantly in the RR of MI injury between ACS and non-ACS patients [RR 1.84 (95% CI = 0.82–4.11); (I2 = 0%; p = 0.98)] (Figure 3). If on the one hand, Briasoulis et al. 15 showed that a FFR‑guided strategy in ACS seems to be associated with a better prognosis compared to an angiography strategy, the primary finding of our study was that deferring the treatment of lesions was associated with an increased risk of MI in ACS patients compared to non-ACS patients, represented by the RRs of the target-vessel revascularization or MI lesion. 15 In addition, mortality and CV mortality did not differ between ACS and non-ACS patients. Our results are consistent with the recently published study by Van Belle et al., 38,39 who compared the impact differing the management of intermediate lesions, based on FFR, on the prognosis of ACS vs . non-ACS patients from two important registries, R3F and POST-iT. They concluded that revascularization decisions based on FFR for differing treatment of lesions were safe in ACS patients. 38-40 Some authors have questioned whether we should be less permissive and adopt a different cut-off value for FFR in unstable vessels. Hakeem et al., 34 recently determined that the best FFR cut-off value for predicting MI or TVR was > 0.80 in patients with stable coronary artery disease, supporting current practice. However, in NSTE-ACS patients, the best cutoff value was >0.84. However, some limitations suggested by some authors deserve consideration in interpreting their results. For example, it is unclear why mortality, the most important outcome, was not included in the composite endpoint in this study. In addition, medical therapy was not optimal for the patients, 14% of patients did not receive statin, 546