Normal standardized left ventricular longitudinal strain curves stratified by age and sex in healthy individuals: the Copenhagen City Heart Study

AIMS: To establish normal sex- and age-specific longitudinal strain curves, to quantify their morphological variation with age, and to demonstrate their utility by deriving novel measures from them with the aim of testing prognostic value. METHODS AND RESULTS: Age- and sex-appropriate normal strain curves were derived from healthy participants of the Copenhagen City Heart Study (CCHS). Four novel measures were constructed: early (EDS) and late (LDS) diastolic strain, primarily to assess age-related variation in strain curve morphology, and mean and diastolic strain deviation. Their prognostic value was assessed using Cox proportional hazards regression and C-statistics internally in the CCHS and externally in the LOOP study against a composite endpoint of cardiovascular death and incident heart failure or atrial fibrillation. In total, 1641 healthy subjects (mean ± standard deviation [SD] age 45.3 ± 15.2 years, 62.3% female) from the CCHS and 1307 (mean ± SD age 74.4 ± 4.0 years, 47.4% female) from the LOOP study were included. EDS decreased with age, while LDS increased. During a median follow-up of 4.9 [interquartile interval: 3.0, 5.6] years, 409 (31.3%) subjects met the outcome in the LOOP study. Mean strain deviation was independently associated with the outcome (adjusted hazard ratio = 1.02 (95% confidence interval: 1.00, 1.05), P = 0.045), while diastolic strain deviation was not. CONCLUSION: We established normal sex- and age-specific longitudinal strain curves and furthermore demonstrated their utility by deriving novel measures from these with prognostic value beyond conventional measures. While promising, further validation in external populations is warranted. The normal curves and relevant code are publicly available.