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Cassius Iyad Ochoa Chaar

Associate Professor of Surgery (Vascular)

Contact Information

Cassius Iyad Ochoa Chaar, MD, MPH, MS, RPVI

Office Location

Research Summary

Dr Chaar’s research focuses on clinical outcomes using large national database analysis such as the ACS-NSQIP , the VQI and the NIS. He also leads multiple clinical trials at Yale New Haven Hospital. He studies and publishes on various aspects of vascular disease including peripheral artery disease, varicose veins, venous thromboembolism, carotid disease and aortic aneurysms. The work of his research team is regularly presented in several regional and national vascular societies scientific meetings including the New England Society of Vascular Surgery (NESVS), the Eastern Vascular Society (EVS), the Vascular and Endovascular Surgery Society (VESS), the American Venous Forum (AVF), the Society of Clinical Vascular Surgery (SCVS), the Society of Vascular Surgery (SVS), and the American Heart Association (AHA).

Dr. Chaar has mentored several trainees in conducting research projects and helped them prepare and present their work at national meetings. He formulates a research project in vascular disease based on the student's interests and the knowledge gap in the literature. His philosophy in research relies on engaging the trainees and making sure they are genuinely interested in the questions they are trying to answer. "That is the key to success", states Dr. Chaar. As such the trainees can chose between a retrospective study based on clinical work done at Yale, a database analysis based on national databases or even can design a small prospective study to examine specific treatments or outcomes of interest. Last, there are always opportunities to write and publish case reports of challenging patients treated with novel techniques or highlighting certain aspects of vascular disease.

Dr Chaar has helped numerous students and trainees publish manuscripts to improve their CV and promote their career specially when applying to competitive residencies and fellowships. Yale medical students that have worked with Dr. Chaar match not only in vascular surgery but also in anesthesiology, cardiology, interventional radiology, internal medicine, ophthalmology and other specialties. Several mentees were able to obtain grants and awards during their research time under his supervision. He is also a thesis mentor for numerous medical students who fulfill this requirement for medical school graduation by expanding on the research work completed during their research time with his team. Due to his dedication to teaching and mentoring, Dr. Chaar received the Charles W. Bohmfalk Award in teaching in clinical sciences in 2020 and the John N Forrest, Jr Mentorship Award in 2023 from the Yale School of Medicine.

As a recent graduate from the Yale School of Public Health (MPH 2023), Dr Chaar has established new collaborations to study clinical genetics of vascular disease, explore applications of artificial intelligence to improve vascular care, and assess new technologies that enhance vascular surgery treatments.

Extensive Research Description

Research Projects for Students and Residents

Project 1:

Title: The significance of reinterventions in the treatment of peripheral artery disease (PAD)

Description: Patients treated with open or endovascular revascularization of the lower extremities undergo frequently repeated intervention to sustain patency and to provide limb salvage in patients with critical limb ischemia. This project studies the impact and costs of reinterventions on patient outcomes.

Project 2:

Title: Prediction model for major amputation in patients with PAD

Description: This patient will rely on large database data to identify factors that can predict major amputation in patients with PAD undergoing lower extremity revascularization.

Project 3:

Title: Characteristics and outcomes of patients with premature vascular disease

Description: Vascular diseases such as peripheral arterial disease, abdominal aortic disease, and carotid disease are typically diseases of the elderly. Yet, some patients present at relatively young age and tend to have different characteristics and more aggressive forms of the disease. This project aims at better identifying the specific risk factors for those patients and better understand their outcomes after vascular surgery.

Project 4:

Title: Universal Algorithm for venous disease

Description: Our understanding of venous disease and its treatment has evolved and there are several structural anomalies that can be surgically treated that can improve patient symptoms. However, there is no recommended and well defined protocol for the approach to the patient. This project studies the effect of the Yale Vascular Surgery protocol on the evaluation and outcomes of patients with venous disease affecting the lower extremities. The protocol was incorporated in a signature care pathway in epic (the electronic medical record). The project will study the impact of this integration on the care of patients with venous insufficiency at Yale New Haven Hospital.

Project 5:

Title: Iliofemoral DVT and post phlebetic syndrome in the DOAC era

Description: This study aims to study the risk of postphlebetic syndrome after iliofemoral DVT in patients on DOAC compared to coumadin. Also, it will assess the incidence of postphlebetic syndrome after different types of DVT. This project is in collaboration with the hematology team.

Project 6:

Title: Management of vascular disease in the very old

Description: As the population ages, vascular surgeons increasingly face complex patients in their 80s and 90s requiring treatment. This project aims to study the trends in treatment of vascular disease in the elderly, as well as the outcomes and focus on the impact on quality of life.

Project 7:

Title: Genetic predictors of revascularization outcomes

Description: This project will use Yale data, UK biobank, and all of us data to identify genetic variants that can be associated with outcome of vascular revascularization. This project involves collaborators in the school of public health and the yale genetics department.

Project 8:

Title: Smoking cessation in vascular patients

Description: Smoking is very prevalent in patients with vascular disease. Patients get advised about smoking cessation all the time. This study looks at different means to enhance cessation in vascular patients in the inpatient as well as the outpatient settings.


Research Interests

Aortic Aneurysm; Varicose Veins; Vascular Diseases; Vascular Surgical Procedures; Thrombolytic Therapy; Venous Thrombosis

Selected Publications

Clinical Trials