Reference values of strain-derived myocardial work indices in heart transplant patients

Aims: Myocardial work (MW) is a relatively novel non-invasive echocardiographic method with increasing fields of application. Normal reference ranges of MW indices in patients who have undergone a heart transplant (HTx) have not been determined yet. The aim of this study was to obtain the reference ranges for 2D echocardiographic indices of MW for adult HTx patients and to compare them with the results of the European Association of Cardiovascular Imaging (EACVI) Normal Reference Ranges for Echocardiography (NORRE) study. Methods and results: All consecutive HTx patients admitted at our institution (University Hospital of Siena, Italy) between September 2019 and May 2022 who underwent endomyocardial biopsy (EMB) were considered. Patients with a history of rejection, a history of coronary artery vasculopathy, either acute cellular rejection or acute antibody-mediated rejection at EMB, and donor-specific antibodies were excluded. MW retrospectively performed for the included patients was retrieved, and the results were compared with those from the EACVI NORRE study. Out of 176 HTx patients who underwent EMB, 94 patients were excluded. The study population consisted of 82 HTx patients [68.3% male, median age 53 (46-62) years]. The median duration from HTx was 5 (2-22) months. The main MW indices such as global work efficiency (GWE, 84 ± 8%), global work index (GWI, 1447 ± 409 mmHg%), global constructive work (GCW, 2067 ± 423 mmHg%), and global wasted work [GWW, 310 (217-499) mmHg%] did not differ according to gender. Each of these indices significantly differed from those reported in the EACVI NORRE study (P-value <0.001), with lower GWI, GCW, and GWE and higher GWW values in the HTx population. Conclusion: This study provides reference ranges for MW indices in an adult HTx population free from transplant-related complications which proved to be different from those previously reported in healthy volunteers.