High-risk pulmonary embolism (PE) is a life-threatening condition characterized by hemodynamic instability due to acute right heart failure. Without urgent reperfusion therapy, close to half of patients with high-risk PE will not survive the acute event. Even when treated using systemic thrombolysis, the guideline-recommended first-line interventional therapy, this patient population has historically demonstrated approximately 30% in-hospital mortality. Recent technological advances, including large-bore mechanical thrombectomy devices, might improve the mortality rate in high-risk PE, but achieving favorable outcomes for these patients first depends on prompt and accurate diagnosis. Patients presenting with systemic hypotension and probable PE based on Wells and Geneva scores, laboratory tests, or other measures should begin anticoagulation therapy and supportive measures while awaiting a definitive diagnosis. Computed tomographic (CT) pulmonary angiography is the standard technique for confirming PE due to its widespread availability and capacity to provide clear and rapid results, and it can also provide quantitative information regarding the severity of right heart dysfunction. Transthoracic echocardiography is also used in the assessment of high-risk PE as another modality to evaluate right heart dysfunction and to rapidly determine whether right heart clot-in-transit is present. The presentation of this abstract will include discussion of clinical findings in the setting of high-risk PE as well as related details regarding the use and interpretation of CT and echocardiographic imaging. Recent clinical studies reporting interventional outcomes in high-risk PE patients will also be discussed.