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