The quantitative assessment of ischaemic heart disease: A study of the Leeds Exercise Test.

Elamin, Mary, Smith Linden, 1980 suggested that the rate of development of ST segment depression with increasing heart rate during a standardised exercise test could predict the number of coronary arteries (0, 1, 2 or 3) seen to be ocluded on the coronary arteriogram. Several attempts to repeat this "Leeds exercise test" had been unsuccessful possibly through inadequate adherence to the Leeds protocol. The work described in this thesis is a further attempt to replicate the Leeds test as precisely as possible after a period of instruction at Leeds. A Leeds test and coronary arteriography were performed on 49 patients at Groby Road Hospital, Leicester. Results of identical exercise ECGs analysed at Leeds and Leicester were compared to ensure the same methods were used and highlight potential causes of disparate results through differences in method. Results of arteriograms assessed at both centres and on two occasions at Leicester were compared to test the reproducibility of the arteriogram and so its value as an index of coronary disease. A computer assisted method of measuring the exercise ECG was developed. The results of coronary arteriography and exercise testing were correlated to assess the Leeds test for the prediction of coronary disease severity. The following main reasons why the Leeds' results have not been repeated at any other centre are proposed: 1. There has been sufficient deviation from the described methods of performing the exercise test and assessing the arteriogram. 2. Patient variables (drug regime and cardiac complications other than coronary disease) may affect the ST/HR slope. 3. There is a large variance associated with the arteriogram result and the estimate of the ST/HR slope. 4. It is questionable that an exact correlation can occur between the results of exercise testing and coronary arteriography. Also, a 3 vessel disease terminology to quantify coronary disease is inadequate. It is recognised that the maximal ST/HR slope is an improved index of myocardial ischaemia which has probably had limited acceptance through being assessed against arteriogram results in terms of 0, 1, 2, and 3 vessel disease. Finally, having highlighted the limitations of exercise testing and coronary arteriography, the potential of nuclear magnetic resonance in the quantitative and qualitative assessment of ischaemic heart disease in the future is addressed.