Objective To summarise existing data on the relation between the time from symptom onset until revascularisation (time to reperfusion) and the myocardial salvage index (MSI) calculated as proportion of non-necrotic myocardium inside oedematous myocardium on T2-weighted and T1-weighted late gadolinium enhancement MRI after ST-segment elevation myocardial infarction (STEMI).
Methods Studies including patients with revascularised STEMI and stating both the time to reperfusion and the MSI measured by T2-weighted and T1-weighted late gadolinium enhancement MRI were searched in MEDLINE, EMBASE and ISI Web of Science until 16 May 2020. A mixed effects model was used to evaluate the relation between the time to reperfusion and the MSI. The gender distribution and mean age in included patient groups, the timing of MRI, used MRI sequences and image interpretation methodology were included in the mixed effects model to explore between-study heterogeneity.
Results We included 38 studies with 5106 patients. The pooled MSI was 42.6% (95% CI: 38.1 to 47.1). The pooled time to reperfusion was 3.8 hours (95% CI: 3.5 to 4.0). Every hour of delay in reperfusion was associated with an absolute decrease of 13.1% (95% CI: 11.5 to 14.6; p<0.001) in the MSI. Between-study heterogeneity was considerable (σ2=167.8). Differences in the gender distribution, timing of MRI and image interpretation among studies explained 45.2% of the between-study heterogeneity.
Conclusions The MSI on T2-weighted and T1-weighted late gadolinium enhancement MRI correlates inversely with the time to reperfusion, which indicates that cardioprotection achieved by minimising the time to reperfusion leads to a higher MSI. The analysis revealed considerable heterogeneity between studies. The heterogeneity could partly be explained by differences in the gender distribution, timing and interpretation of MRI suggesting that the MRI-assessed MSI is not only influenced by cardioprotective therapy but also by patient characteristics and MRI parameters.
- magnetic resonance imaging
- myocardial infarction
- cardiovascular imaging
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Contributors Conceptualisation: BK and MD. Methodology: BK. Data curation: BK and HS. Formal analysis: BK and PS. Supervision: MD and PS. Visualisation: BK. Writing—original draft: BK. Writing—review and editing: MD. Guarantors: BK and MD.
Funding We acknowledge support from the German Research Foundation (DFG), the German Federal Ministry of Education and Research (BMBF) and the Open Access Publication Fund of Charité—Universitätsmedizin Berlin. The funders had no role in the study design; in the data collection, analysis and interpretation of data; in the writing of the report and in the decision to submit the article for publication. The researches were independent from funders. All authors had full access to all of the data (including statistical reports and tables) in the study and can take responsibility for the integrity of the data and the accuracy of the data analysis.
Competing interests MD and PS received financial support from the German Research Foundation (DFG) and the German Federal Ministry of Education and Research (BMBF) for the submitted work; outside the submitted work, MD received grants from the German Foundation of Heart Research, GE Healthcare, Bracco, Guerbet, Toshiba Medical Systems, Siemens Medical Solutions, Philips Medical Systems, German Research Foundation (DFG) and the European Union (funding programme FP7), and personal fees from German Research Foundation (DFG), Guerbet, Cardiac MR Academy Berlin, Bayer-Schering, Toshiba Medical Systems and Springer; outside the submitted work, PS received grants from the German Research Foundation (DFG), European Union and Bayer Pharma AG; no other relationships or activities that could appear to have influenced the submitted work.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement All data relevant to the study are included in the article or uploaded as supplemental information.
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