Optimising radiofrequency catheter ablation of accessory pathways.

any importance to thallium data even in these young patients. Nevertheless, it is open to speculation whether this important subgroup is characterized by a special anatomical substrate' or pathophysiological mechanism leading to an extraordinarily high degree of subendocardial ischaemia. Mainly because of methodological problems, ambulatory ST-monitoring seems to be of limited value for ischaemia screening in hypertrophic cardiomyopathy patients. One exception may be a subgroup of younger patients, but this still remains to be investigated. The ability of the various invasive and non-invasive hypertrophic cardiomyopathy diagnostics used to detect different mechanisms of ischaemia requires further clarification. Objective markers of ischaemia rather than chest pain or dyspnoea should be used to validate such strategies. Each individual hypertrophic cardiomyopathy patient might require the summation of several such tests to elucidate the ischaemia-triggering profile and to explain symptoms. Individual characterization of ischaemia or the division of the heterogeneous hypertrophic cardiomyopathy population into subgroups with similar mechanisms and anatomic substrates will be important to gain understanding of this complex issue. R. DISSMANN H.-P. SCHULTHEISS Department of Cardiopulmonology, Klinikum Benjamin Franklin, Free University of Berlin, D 12200 Berlin, Germany