HIPAA-Compliant Patient Data Encryption Microservice

Design a Node.js microservice that implements end-to-end encryption for patient medical records stored in MongoDB, ensuring HIPAA compliance. Create a robust encryption strategy using AES-256-GCM that securely handles patient sensitive data (SSN, medical history) with automatic key rotation every 30 days. Implement comprehensive logging mechanisms that track all data access without storing personally identifiable information. Include a detailed threat model explaining how the encryption prevents potential data breaches at rest and in transit.