Prior work linking RDW to echocardiographic findings in PE has largely focused on isolated parameters such as TAPSE or PASP and has rarely incorporated modern measures of RV-PA coupling. Whether admission RDW reflects the integrated RV-PA interaction - and not merely contractility or pressure in isolation - has not been adequately addressed. Establishing this link would support RDW as a simple, universally available marker of RV vulnerability at first presentation, and would lay the groundwork for future prognostic and mechanistic studies.