Age, Sex and Ethnicity-Stratified Strain Reference Ranges in Healthy Individuals from the Healthy Hearts Consortium

Background:
Myocardial strain derived from cardiovascular magnetic resonance (CMR) using feature tracking (FT) provides prognostic information beyond traditional imaging markers. Its broader implementation is limited by the absence of population-specific reference ranges. This study defines age-, sex-, and ethnicity-specific normative values for FT-CMR myocardial strain derived from the Healthy Hearts Consortium (HHC).

Methods:
The HHC is a multicentre international initiative combining CMR data from 9,088 rigorously screened healthy adults across six centres. Participants represented the full adult age spectrum and diverse ethnic backgrounds. CMR scans were acquired using standardized protocols and analysed according to predefined standard operating procedures by two experienced readers on two commercial platforms (CVI42®, suiteHEART®). Extracted parameters included global longitudinal, circumferential, and radial strain for both ventricles and atria, strain rate, annular plane systolic excursion (MAPSE, TAPSE), and rapid strain metrics (long-axis, junctional strain) for ventricles and atria. All analyses underwent quality control with exclusion of biologically implausible or extreme outlier values. Reference ranges were calculated using the 95 % prediction interval method, stratified by age decade (20–80 years), sex, and ethnicity (White, Black, South Asian, Chinese, Mixed/Other). The influence of scanner vendor, magnetic field strength (1.5 T vs 3.0 T), and software platform was evaluated (Details: Figure 1).

Results:
Among 9,088 participants (4,452 men, 4,636 women; mean age 61 ± 13 years), ethnic composition was White 81.7 %, South Asian 5.6 %, Mixed/Other 5.3 %, Black 3.7 %, and Chinese 3.7 %. Women consistently showed higher absolute strain magnitudes than men. Strain values declined progressively with age, most notably for left ventricular circumferential and longitudinal strain. Ethnic differences were evident mainly between White and Black, and White and Chinese participants for left and right ventricular strain, whereas atrial and rapid strain metrics displayed minimal ethnic variation.

Conclusion:
This study provides the most comprehensive age-, sex-, and ethnicity-specific reference ranges for FT-CMR myocardial strain to date. These normative values facilitate standardized clinical interpretation and improved risk stratification across diverse populations. The results represent a major step toward integrating myocardial strain assessment into routine cardiovascular magnetic resonance practice.