hs-cTn – Optimizing the Diagnosis of Acute Myocardial Infarction/Injury in Women
Dr. Karin Humphries, Scientific Director, BC Centre for Improved Cardiovascular Health
Dr. Jim Christenson, Professor and Head, Department of Emergency Medicine
Canadian Institutes of Health Research
Females with heart disease are under-diagnosed, under-treated, and have worse outcomes than their male counterparts. Among young women (<55 years) with a heart attack, the risk of death is double than that among men of the same age. With the introduction of a more sensitive diagnostic test – high sensitivity cardiac troponin (hs-cTn), it has become clear that using a single level (cut-point) to identify patients with a heart attack disadvantages females. Hs-cTn is a biomarker (protein) released into the blood when the heart is damaged during a heart attack. Females produce less of this biomarker than males when they have a heart attack. It is anticipated that by using a lower cut-point for hs-cTn for females, more females who have had damage to their hearts will be identified, and this will enable the provision of better care, leading to better outcomes for this population.
This study aims to evaluate the impact of using the female-specific cut-point for hs-cTn compared to the overall cut-point, on the diagnosis, treatment, and outcomes of females presenting to the emergency department with chest pain. Specifically, the impact of female-specific cut-points on the following will be examined:
- Diagnostic and therapeutic strategies;
- Prognosis: 30-day and 1-year all-cause mortality, non-fatal MI, incident heart revascularization; and
- Costs of diagnostic testing and treatment.
The study is a stepped-wedge cluster-randomized trial – a unidirectional crossover design where clusters cross over sequentially, in random order, from the control to the intervention phase. The study will be conducted in 26 emergency departments across Canada. The intervention is essentially a change in ‘process’, namely the implementation of a lower hs-cTn cut-point in females. Every site will start using the standard single cut-point to identify patients with heart attack or heart damage. Randomly, the sites will be asked to change practice in their hospitals by using a lower cut-point for females; the cut-point for males will remain the same. At the end of the study, every emergency department will be using the lower cut-point in females.
The under-diagnosis and under-treatment of females is well documented and persistent. There is also mounting evidence that the rate of heart attacks is increasing in younger females. With the recent adoption of hs-cTn in Canada, we have a unique opportunity to determine whether the use of the lower female cut-point leads to better diagnostic assessment, better treatment, and improved outcomes.