Supplementary Table S1: MMAT Quality Assessment of Studies Investigating Cardiac Fatty Acid Oxidation in HFpEF

The methodological quality of all 44 studies in this review were evaluated using the Mixed Methods Appraisal Tool (MMAT), a standardized framework for assessing research quality. Each study was examined across seven key questions: Did the study have clear research goals? Was the data collection approach appropriate? Did the study include the right participants? Were the measurements done properly? Was all the important data collected? Did researchers account for other factors that might affect results? Was the study carried out as planned? For each question, we provided brief comments explaining our assessment. The final column gives an overall view of each study's quality. This systematic quality assessment enables critical evaluation of the methodological rigor across studies, particularly when reconciling apparent contradictions in the literature regarding cardiac fatty acid oxidation in HFpEF.