Expression of concern relating to: D. Poldermans, E. Boersma, J. J. Bax, I. R. Thomson, B. Paelinck, L. L. M. van de Ven, M. G. Scheffer, G. Trocino, C. Vigna, H. F. Baars, H. van Urk, J. R. T. C. Roelandt, for the Dutch Echocardiographic Cardiac Risk Evaluation Applying Stress Echocardiography Study Group. 'Bisoprolol reduces cardiac death and myocardial infarction in high-risk patients as long as 2 years after successful major vascular surgery'