Node.js is a powerful technology for building scalable applications that can handle a large number of concurrent users. However, building such applications requires careful planning and the use of appropriate architectural patterns to ensure that the code remains maintainable and scalable over time.

Architectural patterns in Node.js refer to the high-level structure of an application or system. These patterns provide a foundation for organizing code, modules, and libraries in a way that makes it easy to maintain and debug the application, while also making it easy to add new features or scale the application as customer needs increase.

1. Model-View-Controller (MVC) - this is a pattern that separates an application into three main components: the model which represents data and logic, the view which is responsible for rendering the data to the user interface, and the controller which provides a means of connecting the view and model.

2. Microservices - this pattern involves breaking an application into smaller, independent services that can be developed and deployed separately. This allows teams to focus on individual components of the application without worrying about the entire codebase, making it easier to maintain, test and deploy.

3. Service Oriented Architecture (SOA) - this pattern is similar to microservices but takes it a step further by creating a network of loosely-coupled, distributed systems that can communicate with each other using standardized protocols. This pattern enables teams to build complex, scalable applications that can adapt to changing market requirements.

By using appropriate architectural patterns in Node.js, developers can build scalable, maintainable applications that are easier to test and deploy. These patterns make it possible to build applications that can evolve over time to meet changing customer needs while keeping technical debt to a minimum.