Equipoise: The basic necessity for conducting a trial on uncomplicated Type B aortic dissection

Area of Science:

• Cardiovascular Surgery
• Medical Ethics
• Clinical Trial Design

Background:

• Clinical equipoise, essential for randomized controlled trials (RCTs), is challenged by the increasing use of thoracic endovascular aortic repair (TEVAR) for uncomplicated type B aortic dissection (uTBAD).
• Optimal medical therapy is the current standard for uTBAD, but TEVAR is increasingly adopted despite limited comparative data.
• Existing RCTs (INSTEAD, INSTEAD-XL, ADSORB) show TEVAR aids false-lumen thrombosis and remodeling but not improved survival over optimal medical therapy.

Purpose of the Study:

• To evaluate the current state of clinical equipoise in the treatment of uncomplicated type B aortic dissection (uTBAD).
• To assess the evidence supporting thoracic endovascular aortic repair (TEVAR) versus optimal medical therapy in uTBAD.
• To highlight the necessity for definitive randomized trials to resolve treatment uncertainties.

Main Methods:

• Review of existing randomized controlled trials (INSTEAD, INSTEAD-XL, ADSORB) and retrospective studies on TEVAR for uTBAD.
• Analysis of contemporary guidelines and factors influencing clinical practice patterns.
• Discussion of the ethical considerations and scientific requirements for resolving treatment equipoise.

Main Results:

• RCTs indicate TEVAR promotes aortic remodeling but have not demonstrated a survival advantage over optimal medical therapy for uTBAD.
• Retrospective studies suggest improved outcomes with TEVAR, but these findings are associative and lack causal evidence.
• Current guidelines recommend aggressive medical therapy with selective TEVAR for high-risk patients, reflecting unresolved treatment uncertainties.

Conclusions:

• Clinical equipoise persists in the management of uTBAD due to insufficient high-level evidence favoring TEVAR over optimal medical therapy.
• Practice patterns are influenced by factors beyond definitive data, including institutional culture and device marketing.
• Adequately powered RCTs focusing on patient-centered outcomes are essential to resolve clinical equipoise and guide optimal uTBAD treatment strategies.