Impact of Age and Heart Rate on Strain-Derived Myocardial Work in a Population of Healthy Subjects

Background: The influence of age and gender on strain-imaging-derived myocardial work (MW) was recently investigated in healthy subjects. No information is available on the impact of heart rate (HR) on MW. Methods: 177 healthy subjects (47% men, mean age 42 years) underwent an echo-Doppler exam, including quantification of global longitudinal strain (GLS). Cuff blood pressure was used as a surrogate of left ventricular peak pressure to estimate global work index (GWI), global constructive work (GCW), global wasted work (GWW) and global work efficiency (GWE). Statistical analyses were performed according to age and HR tertiles. Results: GWW was higher in the third HR tertile, i.e., ≥74 bpm (74.7 ± 33.6 mmHg %) than in the first HR tertile (<66 bpm) (61.0 ± 32.5 mmHg %) (p < 0.02). In the pooled population, by adjusting for systolic blood pressure, GLS, E/e’ ratio and left atrial volume index, age was independently associated with GCW (β = 0.748) and GWI (β = 0.685) (both p < 0.0001) and HR with GWW (β = 0.212, p = 0.006) and GWE (β = −0.204, p = 0.007). Conclusions: In healthy subjects age shows a mild influence on GCW. HR exerts an independent negative impact on GWW and GWE: the higher HR the greater wasted work and lower myocardial efficiency.