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Objective: Since visual estimation of the extent of vessel stenosis may vary between operators, we aimed in this study to investigate both inter-observer variability and consistency between the estimation of an operator and quantitative coronary analysis (QCA) measurements., Methods: A total of 147 elective percutaneous coronary intervention patients with 155 lesions between them were consecutively enrolled in the study. These patients were evaluated for visual estimation of lesion severity by three operators. The lesions were also evaluated with QCA by an operator who was blinded to the visual assessments. Reference diameter, minimal lumen diameter, percentage diameter of stenosis, percentage area of stenosis and diameter of lesion length from the proximal lesion-free segment to the distal lesion-free segment were calculated using a computerised QCA software program., Results: There was a moderate degree of concordance in the categories 70-89% (κ: 0.406) and 90-99% (κ: 0.5813), whereas in the categories < 50% and 50-69% there was a low degree of concordance between the visual operators (κ: 0.323 and κ: 0.261, respectively). There was a low to moderate grade of concordance between visual estimation and percentage area of stenosis by QCA (κ: 0.30) but there was no concordance between visual estimation and percentage diameter of stenosis by QCA (κ: -0.061). Also, there was a statistically significant difference between QCA parameters of percentage diameter of stenosis and percentage area of stenosis (58.4 ± 14.5 vs 80.6 ± 11.2 %, p < 0.001)., Conclusions: Visual estimation may overestimate a coronary lesion and may lead to unnecessary coronary intervention. There was low concordance in the categories < 50% and 50-69% between the visual operators. Percentage area of stenosis by QCA had a low to moderate grade of concordance with visual estimation. Percentage area of stenosis by QCA more closely reflected the visual estimation of lesion severity than percentage diameter of stenosis.

We report on a 37-year-old patient who suffered from myocardial stunning after exposure to carbon monoxide, despite having normal coronary arteries. As myocardial ischaemia may be asymptomatic in these patients, close monitoring with serial electrocardiography and of serum cardiac enzymes and troponins is recommended.