The paper deals with general questions of the Component Object Model (COM) architecture for ECG software applications. Here their common structure is presented, the benefits and constraints of component-based applications are considered. Being a component model, COM allows one to build any application the functionally complete modules. Each module is developed by the particular protocol that gives developers a possibility to provide effective interoperability between such components. The separate part of the article is devoted to reliability and performance issues of the component-based ECG applications. The approach described in this article permits one to solve a number of problems facing medical software developers by using the effective and flexible component architecture. As implementation of the discussed architecture, a software ECG system being developed by a team of authors is presented.