Development and Validation of a Measure of Psychological Distress After Spontaneous Coronary Artery Dissection: The Spontaneous Coronary Artery Dissection Distress Inventory

Background: Spontaneous coronary artery dissection (SCAD) is a highly distressing cause of acute myocardial infarction. No SCAD-specific distress measure currently exists, with researchers relying on generic measures of anxiety, depression, and distress that fail to capture the psychological impacts unique to SCAD. We developed and validated the SCAD Distress Inventory (SDI) to provide a condition-specific distress measure. Methods: The SDI was developed through a multistep process. First, 48 SCAD-related distress items were generated from focus groups with SCAD survivors (N=30) and relevant literature. Items were administered online to survivors of SCAD (N=293, angiography-confirmed), who also provided sociodemographic and medical data and completed validated psychological instruments. Exploratory factor analysis identified underlying dimensions within the item pool and Rasch analysis confirmed dimensionality and refined the scale. Psychometric properties were assessed, including internal consistency (McDonald's ω), construct and discriminant validity (correlations with other validated psychological instruments), and clinically significant cutoff scores. Results: The final SDI comprised 33 items across 4 subscales: challenges to sense of self, fear of recurrence, concerns about reduced capacity, and lack of support and validation. All subscales met required statistical and conceptual criteria. The SDI demonstrated excellent internal consistency (ω=0.88-0.92) and good construct and discriminant validity (correlations significantly higher with cardiac distress and lower with posttraumatic growth). Clinically significant cutoff scores were identified for the scale and subscales. Conclusions: The 33-item SDI was successfully codesigned and validated. It can be used in both research and clinical settings, enabling comprehensive assessment of the unique and multifaceted psychological distress experienced after SCAD.