The size of myocardial infarction and peri-infarction edema are not major determinants of diastolic impairment after acute myocardial infarction

Aims Diastolic dysfunction after myocardial infarction (MI) is a marker of poor prognosis. The relationship between myocardial infarction size (IS), myocardial edema, and diastolic dysfunction is poorly understood, both in the acute phase, and in the development of diastolic dysfunction in the follow-up setting. Using a mechanistic approach could potentially add insights. Methods and results Patients underwent cardiovascular magnetic resonance (CMR) imaging and echocardiography including mechanistic analysis using the parameterized diastolic filling method within 4-7 days (acute) and 6 months after a first acute anterior MI (n=74). Linear regression modeling of echocardiographic diastolic parameters using CMR IS with and without inclusion of the myocardium at risk (MAR) and model comparisons with likelihood ratio tests were performed. Diastolic parameters at 6 months follow-up were modelled using final IS. For most parameters there was no association with acute IS, except for deceleration time (R2=0.24, p<0.001), left atrial volume index (R2=0.13, p=0.01) and the mechanistic stiffness parameter (R2=0.21, p<0.001). Adding MAR improved only the e′ model (adjusted R2 increase: 0.08, p=0.02). At 6 months follow-up, final IS was only associated with viscoelastic energy loss (R2=0.22, p=0.001). Conclusion In acute MI, both IS and MAR are related to diastolic function but only to a limited extent. At 6 months after infarction, increasing IS is related to less viscoelastic energy loss, albeit also to a limited extent. The relationship between IS and diastolic dysfunction seems to be mediated by mechanisms beyond simply the spatial extent of ischemia or infarction. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This study was funded by the Swedish Research Council, the Swedish Heart Lung Foundation, a Stockholm County Council ALF grant and Karolinska Institutet/Stockholm County Council Strategic Cardiovascular Programme ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The Stockholm Regional Board of Ethics gave ethical approval for this work. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes The data that support the findings of this study are available on reasonable request from the first author.