Investigating LVF directly, quantitatively and non-invasively by MUGA helps to validate and to follow up the effectiveness of new kinds of therapy. This is performed in controlled studies comparing groups of patients as demonstrated in the case of intracoronary thrombolysis. But it is also applicable on an individual basis. Contrary to the protocol in controlled studies medication was not discontinued in our patients before and after bypass surgery. This resembles the situation under routine conditions. Therefore the number of patients with reduced LVF was rather small before and after bypass operation. But, and this in the main result of our study, implementing MUGA for follow-up under this conditions can help: 1. To find out early those patients in whom LVF deteriorates postoperatively despite adequate medication. 2. To better define whether in cases of persistent or recurrent angina there is also deterioration of LVF. By this means MUGA can significantly contribute to find out whether reangiography is necessary or not, a question which often is difficult to answer in those patients.