Functional Coronary Angiography Guided Revascularization in STEMI

Reperfusion of the culprit lesion through primary PCI is the standard of care in ST-segment elevation myocardial infarction (STEMI) patients, regardless of their age. The actual gold standard for the management of non-culprit lesions in STEMI patients with multivessel disease (MVD) is angiography-guided complete revascularization. The Complete vs Culprit-only Revascularization to Treat Multi-vessel Disease after Primary PCI for STEMI (COMPLETE) trial randomized 4 041 patients with STEMI and MVD. The main finding was the highly significant reduction of new MI occurrence in the complete group (7.9% vs 5.4%, hazard ratio (HR) 0.68, 95% CI 0.53-0.87, p=0.002). Revascularization was obtained largely by angiographic evaluation (>99%).

After COMPLETE, the subsequent step was to ascertain which complete revascularization strategy should be pursued. In particular, physiology-guided revascularization was compared to an angio-guided strategy. The advantages of physiology against angiography are related to: a) lower number of vessels treated, b) lower number of stents implanted; c) avoidance of a second procedure in negative fractional flow reserve (FFR) patients during primary PCI; d) possibility to optimize the procedure from the physiological standpoint after percutaneous coronary intervention (PCI).

In the Flow Evaluation to Guide Revascularization in Multivessel ST-Elevation Myocardial Infarction (FLOWER-MI), patients with STEMI and multivessel disease who had undergone successful PCI of the infarct-related artery were randomly assigned to receive complete revascularization guided by either FFR or angiography. The primary outcome was a composite of death from any cause, nonfatal myocardial infarction, or unplanned hospitalization leading to urgent revascularization at 1 year. FFR-guided revascularization was associated with lower number of stents implanted per patient (1.01±0.99 versus 1.50±0.86). During follow-up, a primary outcome event occurred in 32 of 586 patients (5.5%) in the FFR-guided group and in 24 of 577 patients (4.2%) in the angiography-guided group (hazard ratio, 1.32; 95% confidence interval, 0.78 to 2.23; P = 0.31). Death occurred in 9 patients (1.5%) in the FFR-guided group and in 10 (1.7%) in the angiography-guided group; nonfatal myocardial infarction in 18 (3.1%) and 10 (1.7%), respectively; and unplanned hospitalization leading to urgent revascularization in 15 (2.6%) and 11 (1.9%), respectively.

The results of the FLOWER-MI trial may suggest that physiology can provide a similar outcome if compared to a conventional angio-guided approach. However, some limitation should be acknowledged: i) rate of events was three-times lower than expected suggesting both a selection bias and the need of a higher number of patients to demonstrate any difference among the two groups; ii) all patients in the FFR-group received a staged procedure to perform physiology assessment diluting one of the major advantages in FFR negative patients, namely the avoidance of a second procedure if physiology is negative; iii) in 16% of patients in the physio-guided group FFR was not performed before PCI, whereas in 82% of patients it was not performed after PCI; iv) even if FFR was associated with lower PCIs, periprocedural MI was three times higher if compared to the angio-group, suggesting its possible underreporting in the angio-group.

After the COMPLETE trial2, the actual standard of care in the management of STEMI patients with MVD is complete revascularization based on angiography. However, this approach may lead to over- or under-estimation of lesions in a relevant portion of patients with negative impact on prognosis. Invasive physiology has been consistently shown to be superior if compared to angio-guided strategy, but it is underutilized in clinical practice mainly due to feasibility issues.

A functional coronary angiography could overcome the applicability issues related to invasive physiology. In addition, it is particularly appealing in the evaluation of non-culprit lesions since:

• It is possible to acquire projection during primary PCI and perform the analysis off-line
• In case of negative assessment, the patient can avoid a second procedure to invasively measure physiology
• It is possible to optimize most of the procedures by the physiological standpoint through the utilization of the virtual-PCI planner tool pre-PCI without the need to repeat physiology after PCI.
• It has been recently shown that if compared to an angio-guided approach, Angiography-derived FFR was able to reduce the incidence of spontaneous MI by 36% Therefore, a strategy based on functional coronary angiography to indicate and guide PCI could be superior if compared to an angio-guided strategy both from the efficacy (CV death, cerebrovascular accident, MI and ischemia-driven revascularization) and from the safety (BARC 3-5, contrast-associated acute kidney injury) standpoint.

Inclusion criteria

• ST-segment elevation myocardial infarction with indication to invasive management
• Multi-vessel disease defined as at least 1 non-culprit coronary artery lesion at least 2.5 mm in diameter deemed at visual estimation with a diameter stenosis % ranging from 50 to 99% amenable to successful treatment with PCI
• Successful treatment of culprit lesion

Exclusion criteria

• Planned surgical revascularization
• Left main as non-culprit lesion
• Non-cardiovascular co-morbidity reducing life expectancy to < 1 year
• Any factor precluding 1-year follow-up
• Prior Coronary Artery Bypass Graft (CABG) Surgery
• Impossibility to identify a clear culprit lesion
• Presence of a chronic total occlusion (CTO)