Development of a long term database for assessing the performance of transient ischemia detectors

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Abstract
We have begun to develop a new annotated long term ambulatory ST-T database. The aim of the database is to be a reference set containing a number of well documented ischemic ST episodes, axis-related non- ischemic ST episodes, episodes of slow ST level drift and mixed episodes to support development and evaluation of detectors capable of accurate differentiation of ischemic and non-ischemic ST events, as well as basic research into mechanisms and dynamics of ischemia. We discuss selection criteria, define the events of interest, and describe the annotation procedure. The ESC DB contains 90 two-hour, two-channel ambulatory records with 368 documented transient ischemic ST episodes, but only 11 non-ischemic ST episodes. Non- ischemic ST episodes, which are of no clinical interest per se, account for many of the false positives of automated ischemic ST detectors. Thus it is particularly important to understand these events and to define their distinctive characteristics in order to improve detector performance. The small number of non-ischemic episodes in the ESC DB does not permit exhaustive study of these differences, however. Furthermore, our previous study on characterization of transient ST segment changes in the ESC DB(3), revealed two additional types of important ST events. We found three cases of "mixed episodes" (non-ischemic episodes containing ischemic episodes within), and 17 cases of significant ( 100 V) slow drift of ST deviation level (15 of which also contain ischemic episodes). We also described striking and varied temporal patterns of transient ischemic ST changes. These observations provoke questions regarding the relationships between these patterns and the underlying mechanisms that are responsible for ischemia. We cannot answer these questions definiti vely, however, since we are not able to observe more than a handful of repetitions of each pattern in the two-hour segments of the ESC DB. We have therefore begun to prepare a new, long- term, ambulatory ST database, in order to support the development and evaluation of detectors capable of more accurate differentiation of ischemic and non-ischemic ST changes, and to provide more examples of non-ischemic episodes, episodes of slow ST level drift and mixed episodes.

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