From the halls of Holy Cross College and the Massachusetts ACEP Conference, ACEP Frontline talks with Dr. Lauren Westafer for a high-yield discussion on two of emergency medicine’s most impactful diagnoses: aortic dissection and pulmonary embolism. Dr. Westafer breaks down the evolving evidence behind D-dimer testing, including the 2026 practice-changing data and ACEP clinical policy updates supporting the use of the Aortic Dissection Detection Risk Score combined with D-dimer to help safely risk stratify select patients with suspected acute aortic syndromes. The conversation explores how this approach may reduce unnecessary advanced imaging while maintaining patient safety, along with practical pearls for identifying the patients who still warrant immediate CTA evaluation. The episode also reviews modern pulmonary embolism diagnosis and management, discussing risk stratification, and disposition decisions. It is a practical, evidence-based conversation focused on improving diagnostic accuracy, reducing over-testing, and delivering high-value emergency care.