Mismatch between morphological and functional assessment of the length of coronary artery disease

https://doi.org/10.1016/j.ijcard.2021.04.046Get rights and content

Highlights

  • The extent of functional disease derived from fractional flow reserve (FFR) pullback curves can be quantified using an automated algorithm.

  • In patients with hemodynamically significant coronary stenosis, lesion length based on QCA and based on FFR pullbacks were not correlated. In contrast, CAD length derived from OCT correlated with functional CAD lenght.

  • The mismatch between the length of anatomical and functional CAD (i.e. FAM) correlated with post-PCI FFR.

Abstract

Background

Morphological evaluation of coronary lesion length is a paramount step during invasive assessment of coronary artery disease. Likewise, the extent of epicardial pressure losses can be measured using longitudinal vessel interrogation with fractional flow reserve (FFR) pullbacks. We aimed to quantify the mismatch in lesion length between morphological (based on quantitative coronary angiography, QCA, and optical coherence tomography, OCT) and functional evaluations.

Methods

This is a prospective and multicenter study of patients evaluated by QCA, OCT and motorized fractional flow reserve pullbacks (mFFR). The difference in lesion length between the functional and anatomical evaluations was referred to as FAM.

Results

117 patients (131 vessels) were included. Median lesion length derived from angiography was 16.05 mm [11.40–22.05], from OCT was 28.00 mm [16.63–38.00] and from mFFR 67.12 mm [25.38–91.37]. There was no correlation between QCA and mFFR lesion length (r = 0.124, 95% CI -0.168-0.396, p = 0.390). OCT lesion length did correlate with mFFR (r = 0.469, 95% CI 0.156–0.696, p = 0.004). FAM was strongly associated with the improvement in vessel conductance with percutaneous coronary intervention (PCI), higher mismatch was associated with lower post-PCI FFR.

Conclusions

Lesion length assessment differs between morphological and functional evaluations. The morphological-functional mismatch in lesion length is frequent, and influences the results of PCI in terms of post-PCI FFR. Integration of the extent of pressure losses provides clinically relevant information that may be useful for clinical decision-making concerning revascularization strategy.

Introduction

Invasive functional assessment of coronary artery disease (CAD) has been regarded as the standard of reference for decision making about revascularization in patients with chronic coronary syndromes. Guidelines advocate evaluating the reduction in coronary flow using pressure-derived indices to decide upon the need for revascularization. [1] Intracoronary pressure measurements are typically performed in the distal segment of the coronary artery reflecting cumulative pressure losses along the epicardial vessel. [2] Focal narrowing can be entirely responsible for the pressure drops; nonetheless, diffuse functional deterioration can be also observed outside angiographic stenotic regions contributing to the total decrease in coronary perfusion pressure. [3]

Coronary angiography remains to date the most utilized method to guide stent implantation. The length of the lesion can be quantified by quantitative coronary angiography (QCA), or alternatively, and more precisely, using intravascular imaging. Both approaches aim to guide stent length selection to restore epicardial conductance and improve myocardial perfusion. In almost a third of patients, however, after an angiographically successful PCI, epicardial conductance remains suboptimal. [4] Patients with persistent low FFR after percutaneous revascularization appear to be at an increased risk of adverse events. [4]

A pullback maneuver during intracoronary pressure measurements identifies the presence, location, magnitude and extent of pressure drops. [5] Two factors, namely (i) the magnitude of FFR drops and (ii) extension of functional CAD, are predictive of improvement in epicardial conductance after percutaneous revascularization. [3] Thus, quantifying the extent of functional CAD may have prognostic capability for post-PCI FFR.

Our aim was to quantify the mismatch in the extent of CAD between morphological and functional evaluations and to assess the impact of the morphological and functional mismatch on FFR after PCI.

Section snippets

Study design

This is a multicenter, prospective registry of patients undergoing clinically indicated coronary angiography in whom motorized FFR pullback evaluations were performed before PCI. Patients presenting with acute coronary syndromes, previous coronary artery bypass grafting, significant valvular disease, severe obstructive pulmonary disease or bronchial asthma, coronary ostial lesions, severe tortuosity, or severe calcification were excluded. Patients with adequate pressure tracings and pullback

Results

Clinical characteristics of patients are shown in Table 1. Overall, 117 patients (131 vessels) were included: 71 patients (81 vessels) in the derivation cohort and 48 patients (50 vessels) in the validation cohorts. In the validation cohort, QCA and OCT lesion lengths were available for 50 and 36 vessels, respectively (Table 2). FFR motorized pullbacks pre and post PCI were available in all cases. The relationship between FFR and QCA-based MLA and QCA-based MLD are shown in Fig. S4. The

Discussion

The present study describes a novel approach for the quantification of the extension of functional CAD. This allowed to determine the mismatch in the extent of CAD between anatomical and physiological invasive evaluations based on angiography, intravascular imaging and intracoronary hyperemic pressure pullbacks. The main findings can be summarized as: (1) the extent of functional disease derived from FFR pullback curves can be quantified using an automated algorithm; (2) in patients with

Limitations

The present study has several limitations. First, the performance of FAM is presented based on its relationship with post PCI FFR and not directly with clinical outcomes. Nonetheless, post-PCI FFR have identified as an independent predictor of adverse events after PCI. Second, the sample size of the study was relatively small; however, this is one of the most completely evaluated cohorts with motorized FFR pullbacks and OCT pre- and post-PCI. Third, we were able to validate the FAM concept

Conclusion

Lesion length assessment differs between morphological and functional evaluations. The morphological functional mismatch in lesion length was frequent, often large, and influenced the results of PCI in terms of coronary physiology. Integration of the extent of pressure losses provides clinically relevant information that may be useful during PCI.

Disclosures

The authors take responsibility for all aspects of the reliability and freedom from bias of the data presented and their discussed interpretation. JS report research grants provided by Cardiopath PhD program. BDB reports receiving research grants from Boston Scientific and Abbott Vascular. CaC reports receiving research grants from Biosensor, Coroventis Research, Medis Medical Imaging, Pie Medical Imaging, Cathworks, Boston Scientific, Siemens, Heart Flow Inc. and Abbott Vascular; and

References (11)

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