Cardiac repolarization and the safety of new drugs defined by electrocardiography.

A compelling assessment of both short- and long-term cardiac safety is increasingly emphasized before regulatory marketing approval. In that context, cardiac adverse effects that were otherwise unexpected become manifest when large numbers of subjects are treated after market approval, many of whom take multiple medications, have co-morbidities, and are subject to other conditions that were not represented in the original clinical trial population. Since 2005, dedicated, robust, and well-controlled electrocardiogram (ECG) trials are required, usually conducted in Phase II, to define the cardiac risk of a new therapy before large-scale Phase III trials are conducted or marketing is approved.