Paradigm Shift in Ischemia Evaluation and Accumulating Evidence of Safety of Deferred Coronary Revascularization on the Basis of Invasive Fractional Flow Reserve Measurement
Article ID: CJ-22-0204
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Article ID: CJ-22-0204
Recently, the management of stable coronary artery disease (CAD) or chronic coronary syndrome has been hotly debated, including the diagnostic pathway of CAD and the role of coronary revascularization. The ISCHEMIA trial compared an invasive strategy (angiography and revascularization when feasible) with a conservative strategy of medical therapy alone in stable CAD patients with moderate to severe ischemia, and reported no significant advantage of coronary revascularization over optimal medical therapy alone.1 In that study, furthermore, it was reported that ischemia severity, assessed by stress nuclear myocardial perfusion imaging, stress echocardiography, stress cardiac magnetic resonance imaging, or non-imaging exercise tolerance testing, was not associated with increased risk for death, but the anatomical extent of CAD was associated with an increased mortality risk.2
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In the current JCS updated clinical guidelines on diagnosis and treatment in patients with stable CAD, coronary computed tomography angiography (CCTA), as well as functional imaging test, is graded as a Class I recommendation for patients with intermediate or high pretest probability of CAD, and is recommended as the preferred imaging to rule out the presence of CAD in intermediate pretest probability3 (Figure).
Optimal diagnostic flowchart for non-invasive imaging. CAC, coronary artery calcium; CAD, coronary artery disease; CCTA, coronary computed tomography angiography; CKD, chronic kidney disease; FFR-CT, fractional flow reserve (FFR) derived from coronary computed tomography angiography; LMCA, left main coronary artery; MRI, magnetic resonance imaging; OMT, optimized medical therapy. (Reproduced with permission from Nakano S, et al.3)
Regarding ischemia evaluation, the diagnostic accuracies of functional non-invasive tests are not high enough and the results are known to vary among modalities.4,5 Under these circumstances, clinical evidence for the utility of fractional flow reserve (FFR) measurement during coronary angiography has been accumulating, not only on the benefits of FFR-guided percutaneous coronary intervention (PCI), but also the safety of deferring coronary revascularization based on the FFR value.6,7
The J-CONFIRM registry (long-term outcomes of Japanese patients with deferral of coronary intervention based on fractional flow reserve in a multicenter registry) enrolled 1,263 consecutive patients with angiographically intermediate coronary lesions and deferred revascularization after FFR assessment in 28 Japanese centers between 2013 and 2015.8 In this registry, the 5-year cumulative incidences of cardiac death and target vessel-related myocardial infarction (TVMI) were only 1.9% and 0.95%, respectively, confirming the long-term safety of deferral of coronary revascularization based on FFR.8 In this issue of the Journal, Ueki et al9 report the outcomes of elderly patients after deferral of coronary revascularization in the J-CONFIRM registry. The 5-year cumulative incidence of the primary endpoint of target vessel failure was 14.3% in elderly (aged ≥75 years) patients and 10.8% in younger patients (aged <75 years) (P=0.12). Although the cumulative incidences of cardiac and non-cardiac death were significantly higher in elderly than in younger patients (4.4% vs. 0.8%, P<0.001, and 16.1% vs. 3.9%, P<0.001, respectively), those of TVMI and clinically driven target vessel revascularization (CDTVR) were not significantly different between the 2 groups (1.3% vs. 0.9%, P=0.80, and 10.7% vs. 10.1%, P=0.80, respectively). Considering the equivalent risk for ischemic events such as TVMI and CDTVR between elderly and young patients, the higher cardiac mortality risk in elderly patients is suggested to be largely attributable to age-related cardiac risk itself but not to the deferred lesion-related event risk. Therefore, this study “confirmed” the safety of deferral of coronary revascularization based on FFR measurement in elderly patients, which is an important category of patients in a rapidly aging society. Actually, FFR-guided PCI has become widespread in daily clinical practice in Japan in recent years, and it is important for Japanese physicians that the J-COMFIRM registry properly shows that the current FFR-based deferral revascularization strategy was safe. The next step is we need to examine how to correctly detect hemodynamically significant ischemia non-invasively and whether new technologies such as FFR derived from CCTA (FFRCT) can be a valid option in daily clinical practice. The other important issue for the management of stable CAD is to verify whether FFR-guided coronary revascularization not only improves symptoms but also prognosis compared with optimal medical therapy alone.
H.S. reports honoraria from Abbott Vascular, Boston Scientific, and Daiichi Sankyo, and received research funds from Mizuho Company.
