Abstract
Introduction Cardiac MRI (CMR) is the gold standard technique to assess bi-ventricular volumes and function and is increasingly being considered as an endpoint in clinical studies. Currently, with the exception of right ventricle (RV) stroke volume and RV end-diastolic volume, there is only limited data on minimally important differences (MIDs) reported for CMR metrics. Our study aimed to identify MIDs for CMR metrics based on FDA recommendations for a clinical outcome measure that should reflect how a patient feels, functions or survives.
Methods Consecutive treatment-naïve patients with PAH between 2010 and 2022 who had two CMR scans (at baseline prior to treatment and 12 months following treatment) were identified from the ASPIRE registry. All patients were followed up for one additional year after the second scan. For both scans, cardiac measurements were obtained from a validated fully automated segmentation tool. The MID in CMR metrics was determined using two distribution-based (0.5 standard deviation and minimal detectable change) and two anchor-based methods (change difference and generalised linear model regression) benchmarked to how a patient “feels” (emPHasis-10 questionnaire), “functions” (incremental shuttle walking test) or “survives” for one-year mortality to changes in CMR measurements.
Results 254 patients with PAH were included (aged 53±16 years, 79% female, and 66% categorised as intermediate risk based on 2022 ESC/ERS risk score,). We identified a 5% absolute increase in RV ejection fraction and a 17 mL decrease in RV end-diastolic or end-systolic volumes as the MIDs for improvement. Conversely, a 5% decrease in RV ejection fraction and a 10 mLincrease in RV volumes were associated with worsening.
Conclusion This study establishes clinically relevant CMR MIDs for how a patient feels, functions or survives in response to PAH treatment. These findings provide further support for the use of CMR as a clinically relevant clinical outcome measure and will aid trial-size calculations for studies using CMR.
Footnotes
This manuscript has recently been accepted for publication in the European Respiratory Journal. It is published here in its accepted form prior to copyediting and typesetting by our production team. After these production processes are complete and the authors have approved the resulting proofs, the article will move to the latest issue of the ERJ online. Please open or download the PDF to view this article.
Conflict of Interest: All authors have nothing to disclose.
- Received November 20, 2022.
- Accepted May 23, 2023.
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