Background Athlete's heart, characterized by cardiac chambers adaptations to exercise has some diagnostic overlaps with dilated cardiomyopathy (DCM). In the setting of differential diagnosis, myocardial work indexes (MWI), afterload-independent tool, could be helpful to identify early subclinical alterations. The aim of our study was to assess the utility of MWI in athletes with mildly reduced left ventricular ejection fraction (LVEF). Methods We enrolled 306 Olympic athletes (55.5% males) practicing endurance and mixed disciplines, mean age 26.3±4.3 y.o., who underwent cardio-pulmonary exercise test (CPET) and transthoracic echocardiogram. Athletes were divided in those with lower (<55%) and normal LVEF (=55%). Strain rate and MWI were performed and the following parameters collected: global longitudinal strain, global myocardial work index (GWI), constructive myocardial work (CMW), wasted myocardial work (WMW) and global cardiac work efficiency (GWE). Results Twenty-seven athletes had LVEF<55% (mean 51.5±2.6%). Athletes with EF<55% presented larger LVEDVi (79.1±15.7 vs. 73.2±13.8 mm/m2, p=0.035), LV mass (p=0.049) and LAVi (p=0.016). No differences were found in GWI (1757.9±242 vs 1839.8±255.6 mmHg%, p=0.112), GCW (2121.6±269.3 vs. 2209.3±281 mmHg%, p=0.124), GWW (95.2±40.7 vs. 87.1±47.4 mmHg%, p=0.394) or GWE (95.2±1.7 vs. 95.7±2%, p=0.181). At CPET, in those with EF<55%, higher Watts (340.±83.7 vs. 291.6±84.8, p=0.004), VO2 mL/min/Kg (51.0±13.5 vs. 46.0±10.1, p=0.020) and O2 pulse (23.5±4.6 vs. 21±5.3, p=0.020) were found. Conclusions MWI could be used as additive tool to characterize the physiologic nature of mildly reduced EF of endurance athletes, presenting with better functional parameters but preserved MWI values. MWI may be helpful in differential diagnosis of athlete`s heart from DCM.
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