Background
Many challenges are posed by the experience of a heart attack or heart surgery which can be characterised as ‘cardiac distress’. It spans multiple psychosocial domains incorporating patients’ responses to physical, affective, cognitive, behavioural and social symptoms and experiences related to their cardiac event and their recovery. Although some measures of the psychological and emotional impacts of a cardiac event exist, none provides a comprehensive assessment of cardiac distress. To address this gap, the study aimed to develop a Cardiac Distress Inventory (CDI) using best practice in instrument design.

Method
An item pool was generated through analysis of cognate measures, mostly in relation to other health conditions and through focus group and individual review by a multidisciplinary development team, cardiac patients, and end-users including cardiac rehabilitation co-ordinators. The resulting 144 items were reduced through further reviews to 74 for testing. The testing was carried out with 405 people recruited from three hospitals, through social media and by direct enrolment on the study website. A two-stage psychometric evaluation of the 74 items used exploratory factor analysis to extract the factors followed by Rasch analysis to confirm dimensionality within factors.

Results
Psychometric analysis resulted in the identification of 55 items comprising eight subscales, to form the CDI. The subscales assess fear and uncertainty, disconnection and hopelessness, changes to roles and relationships, overwhelm and depletion, cognitive challenges, physical challenges, health system challenges, and death concerns. Validation against the Kessler 6 supports the criterion validity of the CDI.

Conclusion
The CDI reflects a nuanced understanding of cardiac distress and should prove to be a useful clinical assessment tool, as well as a research instrument. Individual subscales or the complete CDI could be used to assess or monitor specific areas of distress in clinical practice. Development of a short form screening version for use in primary care, cardiac rehabilitation and counselling services is warranted.