Echocardiographic reference ranges of myocardial work indices from the HUNT4Echo study

Reference ranges for myocardial work indices are limited by the scarcity of data from the clinically relevant group of elderly individuals. Myocardial work indices constitute load-adjusted left ventricular function, and main components include global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE).

To establish reference values for myocardial work indices and pressure-strain loop shape from guideline-directed recordings in a healthy population spanning a broad age range.

We assessed myocardial work in healthy participants from the HUNT4Echo study. Global longitudinal strain was obtained by two expert cardiologists using two-dimensional speckle tracking, and systolic blood pressure from brachial measurements. Timing of valve events was performed by a single observer supervised by the expert cardiologists. Among 1239 participants (mean age 57, 55% female), reference ranges for myocardial work indices were as follows: GWI 1367-2583 mmHg%, GCW 1664-2972 mmHg%, GWW 38-328 mmHg%, and GWE 88-98%. Age was associated with lower GWI and GWE, and higher GCW and GWW (all P < 0.05). Sex influenced myocardial work indices, with somewhat higher GWI and GCW in females (P ≤ 0.001). The shape of the pressure-strain loops was narrower in older groups, while GWI (the area encompassed by the loop) remained constant across age groups.

Myocardial work indices were influenced by age and sex, but effects were minor and have limited clinical relevance. Despite preserved GWI by higher age, the pressure-strain loop shape changes significantly - underscoring the importance of integrating strain and afterload when assessing left ventricular function.

Not applicable.