The Year in Cardiology

Coronary Interventions: The Year in Cardiology 2019

Andreas Baumbach; Christos V. Bourantas; PatrickW. Serruys; William Wijns


Eur Heart J. 2020;41(3):394-405. 

In This Article

Invasive Diagnostic Tools

Coronary Physiology

Recent studies have shown that the fractional flow reserve (FFR) and the resting indices including the instantaneous wave free ratio (iwFR) have a value not only in guiding revascularization but also in assessing the final results post-PCI and predicting prognosis.[35,36] There are however occasional discordances between hyperaemic FFR and resting indices. Several studies this year attempted to examine the physiological characteristics of lesions with discordant FFR and iwFR and identify lesion types and subgroup of patients where FFR should be preferred to iwFR and vice versa.[37,38] A recent sub-analysis of the Functional Lesion Assessment of Intermediate Stenosis to Guide Revascularization (DEFINE-FLAIR) study comparing outcomes in patients with a lesion in the left anterior descending coronary artery deferred from revascularization based on the FFR or iwFR estimations showed a lower event rate in the iwFR group at 1-year follow-up that was attributed to a lower incidence of unplanned revascularizations (2.22% vs. 4.99%, P = 0.03).[39] Conversely, a post hoc analysis of the same study in diabetic patients showed no differences in outcomes between the FFR and iwFR groups (7.2% vs. 10.0%; P = 0.30); however, the incidence of non-fatal MI was higher in the iwFR group (4.7% vs. 1.9%; P = 0.05) with a significant interaction for the presence of diabetes (P = 0.04).[40]

In parallel with the introduction of the resting indices for the assessment of the functional severity of intermediate lesions, efforts have been made to design computerized-based methodologies that are able to post-process coronary angiography or invasive imaging data to derive FFR. In 2019, two new solutions have been presented for computational-derived FFR: the first relies on three-dimensional quantitative coronary angiography to derive vessel geometry and estimate the pressure drop across a lesion, while the second on the processing of OCT imaging data; the latter enables combined morphological and physiological assessment of atherosclerotic lesions and of the procedural results post-PCI.[41,42] Preliminary validation of these solutions showed promising results; however, further evaluation of their efficacy in a large number of patients is required before their broad application in the clinical arena.

Intravascular Imaging

Cumulative evidence has highlighted the value of IVUS in guiding PCI. A meta-analysis of randomized controlled trials published this year including 4724 patients underscored the prognostic benefit of IVUS guidance, demonstrating a lower incidence in MACE (5.4% vs. 9.0%; P < 0.001), cardiac death (0.6% vs. 1.2%, P = 0.03), TLR (3.1% vs. 5.2%, P = 0.001), and definite/probable stent thrombosis (0.5% vs. 1.1%, P = 0.02) rates in the IVUS-guided compared to the angiography-guided group.[43] In line with the above findings, the 5-year follow-up analysis of the Impact of Intravascular Ultrasound Guidance on Outcomes of XIENCE PRIME Stents in Long Lesions (IVUS-XPL) study that included 1400 patients with long lesions ≥28 mm randomized to IVUS- and angiography-guided PCI, reported a lower incidence of MACE (5.6% vs. 10.7%, P = 0.001) in the IVUS-guided group attributed to a lower incidence of TLR (4.8% vs. 8.4%, P = 0.007). A landmark analysis for the follow-up period 1–5 years indicated that IVUS guidance was associated with clinical benefit at long-term follow-up (HR 0.53, 95% CI 0.29–0.95; P = 0.031).[44] These findings highlight the prognostic implications of IVUS in guiding revascularization and support its routine use to optimize procedural results and improve the short- and long-term outcomes post-PCI.

Fractional flow reserve is currently recommended to guide revascularization in patients with a chronic coronary syndrome and intermediate lesions. The FORZA study examined the value of OCT in deferring PCI; the study included 350 patients with intermediate lesions who were randomized to OCT- and FFR-guided PCI.[45] Revascularization in the OCT group was performed based on area stenosis and minimum lumen area cut-off values, while in the FFR group PCI was performed if the FFR was ≤0.80. OCT and FFR were repeated in the two groups and used to optimize stent deployment. At 13 months of follow-up, OCT-guided PCI was associated with a higher incidence of revascularization and increased cost while there was no difference in the incidence of MACE—defined as the composite endpoint of all-cause death, MI, target vessel revascularization—between the FFR- and OCT-guided groups (8.0% vs. 3.4%, P = 0.064). For the primary endpoint of the study, i.e. the incidence of MACE and significant angina at 13 months of follow-up, OCT-guided PCI was marginally superior to FFR-guidance (14.8% vs. 8.0%, P = 0.048). The FROZA study is the first that compared in a randomized fashion intravascular imaging vs. physiology guided PCI revealing limitations of both approaches in guiding revascularization (i.e. increased procedural cost and number of vessels treated in the OCT-guided group and a higher incidence of MACE and angina symptoms in the FFR-guided group). Combined physiology and imaging-guided revascularization is likely to overcome the limitations of both modalities and optimize procedural results and the clinical outcomes of patients with obstructive CAD.

In 2019, the European Association of Percutaneous Cardiovascular Interventions published an expert consensus document about the value of intravascular imaging in guiding treatment in ACS and in ambiguous coronary angiography findings.[46] This report highlights the value of intravascular imaging and in particular of OCT in identifying the culprit lesion when this cannot be detected by coronary angiography and in tailoring therapy in patients admitted with an ACS (Figure 3). It also underscores the value of intravascular imaging in assessing ambiguous coronary angiographic findings, in detecting embolic events and intramural haematomas, in assessing lesions caused by an external compression of the vessel by other organs and it summarizes the evidence that supports its role in identifying vulnerable plaques and high-risk patients (Figure 4).

Figure 3.

Value of intravascular imaging in guiding treatment in patients admitted with an acute coronary syndrome. Intravascular imaging (intravascular ultrasound or optical coherence tomography) can be considered in patients with obstructive coronary artery disease in case of a low-risk profile, atypical presentation or complex lesion morphology. In case of multivessel disease, hazy lesions or tortuosity/eccentricity intravascular imaging can be used to identify the culprit lesion while in the absence of obstructive coronary artery disease or in the presence of normal coronary angiogram when there are regional wall motion abnormalities and electrocardiographic changes invasive imaging can be used to exclude a plaque event. Optical coherence tomography can be used to differentiate plaque rupture, plaque erosion identify an erupted calcific nodule, spontaneous coronary dissection, or thromboembolic event; in the absence of a culprit lesion magnetic resonance imaging can be considered to identify other causes such Tako-tsubo cardiomyopathy or myocardial infarction with non-obstructive coronary arteries. Figure was obtained with permission from Johnson et al.46

Figure 4.

Summary of the studies investigating the efficacy of intravascular imaging in detecting high-risk plaques and patients. The studies' endpoints, the imaging predictors and the hazard ratio and the confidence interval of the imaging biomarkers are summarized, while the positive and negative predictive values are shown only for large scale studies with more than one imaging biomarkers as independent predictor. ACS, acute coronary syndrome; CI, confidence interval; DS, diameter stenosis; ESS, endothelial shear stress; FCT, fibrous cap thickness; LCBI, lipid core burden index; MI, myocardial infarction; MLA, minimum lumen area; NPV, negative predictive value; PB, plaque burden; PCI, percutaneous coronary intervention; PPV, positive predictive value; RI, remodelling index; TCFA, thin cap fibroatheroma.

Non-invasive Imaging

Non-invasive functional imaging has an established role in the diagnosis of obstructive CAD in symptomatic patients.[47] In the Myocardial Perfusion CMR vs. Angiography and FFR to Guide the Management of Patients with Stable Coronary Artery Disease (MR-INFORM) study, non-invasive imaging and in particular cardiac magnetic resonance (CMR) imaging was found to be not only useful for the diagnosis of CAD but also for guiding revascularization.[48] In this study, 918 patients were randomized to CMR- or FFR-guided revascularization. CMR-guided PCI was associated with a lower incidence of coronary angiography and PCI (35.7% vs. 45.0%, P = 0.005). At 1-year follow-up, there was no difference between groups for the primary endpoint of all-cause mortality, MI, or target vessel revascularization (3.6% vs. 3.7%, P = 0.91). This report is among the few that compared the role of non-invasive imaging vs. invasive guidance for PCI. A limitation of this study is the fact that the event rate was lower than the 10% event rate assumed in the power calculation and thus it may have been underpowered in detecting differences in outcomes between the two study groups.

Similar were the findings of the Complete Revascularization or Stress Echocardiography in Patients With Multivessel Disease and ST-Segment Elevation Acute Myocardial Infarction (CROSS-AMI) study that compared angiography vs. stress echocardiography-guided revascularization in patients admitted with a STEMI that had non-culprit lesions with a diameter stenosis >50% on quantitative coronary angiography.[49] The study was prematurely stopped after enrolling 77% of the patients because of a slow recruitment (n = 306). The authors reported a higher incidence of non-culprit lesion revascularization in the angiography group (88% vs. 22%). At 1-year follow-up, there were no differences between groups for the primary endpoint of cardiac death, MI, coronary revascularization, or re-admission because of heart failure (14% vs. 14%, P = 0.85). A limitation of the CROSS-AMI study was the fact that it was underpowered to assess differences between groups. Therefore, further research is needed to examine the value of non-invasive imaging in guiding revascularization in patients with an ACS.