Background: Several trials have shown the prognostic benefit of fractional flow reserve (FFR)-guided complete revascularization in patients with acute coronary syndromes (ACS) and multivessel disease compared to an angiography-guided strategy. With the increasing number of elderly ACS patients, evidence-based therapeutical concepts for this high-risk group need to be developed. The need for pressure-wire advancement and induction of hyperemia, along with aprolonged procedural time, are among the reasons for underusage of established functional methods such as FFR. Quantitative flow ratio (QFR) represents an angiography-based tool for fast functional evaluation of coronary stenoses and may therefore serve as attractive alternative to FFR in elderly patients with ACS. 

Purpose: The aim of this study was therefore to investigate the prognostic value of angiography-based pancoronary functional assessment in a cohort of octogenarian patients with ACS.

Methods: A total of 792 patients with ACS undergoing percutaneous coronary intervention (PCI) of the culprit lesion were included in the analysis.Patients were dichotomized according to age (Group 1: age <80 years and Group 2: age ≥80 years). 3D-QCA and QFR analyses were performed in non-culprit vessels and post-PCI culprit vessels at the institution’s core laboratories by investigators blinded to clinical outcomes. The primary endpoint was defined as MACE, a composite of all-cause mortality, non-fatal myocardial infarction and ischemia-driven revascularization within two years after the index ACS event. All events were adjudicated by independent investigators blinded to functional assessment. 

Results: Median age was 65 [56-73] in Group 1 (n=654) and 84 [81-87] in Group 2 (n=138). There was no significance difference in the presence of cardiovascular risk factors as hypertension (97.1% vs. 94.8, p=0.28) or dyslipidemia (56.5% vs. 54.4%, p=0.68), while type 2 diabetes (31.2% vs 21.1%, p<0.05) and prior PCI (24.6% vs. 16.7%, p<0.05) were more frequent in Group 2, and left ventricular ejection fraction (LVEF) was (45.0% vs. 55.0%, p<0.001).

Non-culprit vessel QFR values  of Group 2 were lower (0.96 [0.90-0.99] as compared to the ones of Group 1 (0.97 [0.92-0.99], p<0.05), with corresponding lower residual minimum lumen diameters (1.60 [1.30-2.00] mm vs. 1.70 [1.38-2.10] mm, p<0.05). Post-PCI culprit-vessel QFR was similar among groups (0.96 [0.91-0.99] vs. 0.97 [0.93-0.99], p=0.28). Rates of MACE did not differ between groups (13.0% vs.11.6%, p=0.10). An optimal cut-off value of 0.89 for post-PCI culprit vesseland 0.85 for non-culprit vessel QFR,  emerged as independent predictor of MACE in both groups. QFR values were strongly associated with outcomes (Group 1:  adjusted OR 3.50, 95% CI 1.87-6.56, p<0.001 for post-PCI culprit artery QFR and adjusted OR 4.03, 95% CI 2.18-7.44, p<0.001 for non-culprit artery QFR; Group 2: adjusted OR 4.94, 95% CI 1.43-17.02, p<0.001 for post-PCI culprit artery QFR; and adjusted OR 7.81, 95% CI 2.11-28.97, p<0.001, for non-culprit artery QFR). 

Conclusions: The present study demonstrates that pancoronary QFR independently predicts rates of MACE in octogenarians suffering an ACS event. These results strongly support an angiography-based functional approach to precise risk stratification and guide therapeutic management after an ACS event, particularly in the increasing high-risk group of elderly patients.