How good are experienced interventional cardiologists at predicting the functional significance of intermediate or equivocal left main coronary artery stenoses?

Abstract

Background

Decisions for coronary revascularisation are frequently based on visual assessment of the severity of a stenosis. In patients with intermediate left main stem lesions clinical decision making based on FFR is safe and feasible. This study was performed to assess the accuracy of visual angiographic assessment of intermediate or equivocal left main coronary artery (LMCA) stenoses by experienced interventional cardiologists when taking fractional flow reserve (FFR) measurements as the gold standard.

Methods

Fifty-one patients with intermediate (40–80% diameter stenosis by angiography) or equivocal LMCA disease were evaluated by FFR. Angiograms were then reviewed by 4 experienced interventionalists from different university hospitals blinded to FFR results. Lesions were visually assessed and their significance classified as ‘significant’, ‘not significant’, or ‘unsure’ if the observer was unable to make a decision regarding lesion significance based on the angiogram.

Results

Results were compared with two different FFR cutoff values (< 0.75 and ≤ 0.80) for hemodynamic significance. The 4 reviewers achieved correct lesion classification in no more than approximately 50% of cases each, regardless of FFR threshold. The interobserver agreement between two reviewers in excess of the agreement expected due to chance was outperformed on average by only 16%. Furthermore, interobserver variability was large resulting in unanimously correct lesion classification in only 29% of all cases.

Conclusions

The functional significance of intermediate and equivocal LMCA stenoses should not be based solely on angiographic assessment even by experienced interventional cardiologists.

Introduction

Coronary angiography still remains the standard tool for the evaluation of coronary artery stenoses. While angiographic assessment of very severe and very mild lesions usually is straightforward, the correct interpretation of intermediate lesions may be more challenging [1], [2], [3]. Many experienced interventional cardiologists rely on their skills to assess the functional significance of a coronary lesion by careful visual inspection and the integration of other less quantifiable variables. However, due to the shortcomings of angiography and the limitations of quantitative coronary angiographic (QCA) analysis, the angiographic assessment of a left main coronary artery (LMCA) stenosis may often be particularly difficult and unreliable and may not correlate with its functional significance [4], [5], [6]. Because LMCA disease is mainly encountered in association with disease elsewhere in the coronary tree [7], conventional non-invasive stress tests may not discriminate between inducible ischemia caused by a LMCA stenosis or by other coronary lesions [8], [9], [10]. The assessment of the functional significance of LMCA lesions, however, is of clinical importance, since patients with a LMCA stenosis will usually be referred to surgery. Nevertheless, angiographic evaluation often remains the cornerstone for interventional cardiologists in determining which therapy should be recommended to the patient. It is the aim of this study to investigate how experienced interventional cardiologists predict the functional significance of intermediate (diameter stenosis 40–80%) or equivocal LMCA stenoses based on angiographic criteria. For gold standard, measurement of coronary pressure derived myocardial fractional flow reserve (FFR) was used.