Background The estimation of myocardial work by pressure strain loops (PSLs) is a totally new non‐invasive approach to assess myocardial performance, and its role in patients with hypertrophic cardiomyopathy is unknown. The aims of the present study are therefore: (a) to compare myocardial work in patients with non‐obstructive hypertrophic cardiomyopathy (HCM) and in a subset of age‐matched healthy controls and (b) to assess the correlation between myocardial work and left ventricular (LV) fibrosis. Design Eighty‐two patients with non‐obstructive HCM (58 ± 14 years) and 20 age‐matched healthy subjects (58 ± 7 years, P = 0.99) underwent standard and speckle‐tracking echocardiography to assess myocardial dimensions and deformation parameters. PSLs analysis was used to estimate global myocardial constructive work (GCW) and wasted work (GWW). LV fibrosis was estimated at cardiac magnetic resonance (CMR) by qualitative assessment of late gadolinium enhancement (LGE), and significant fibrosis was defined as LGE in ≥2 LV segments. Results Global constructive work (1599 ± 423 vs 2248 ± 249 mm Hg%, P < 0.0001) was significantly reduced in HCM compared to the control group. No difference was observed in GWW (141 ± 125 vs 101 ± 88 mm Hg%, P = 0.18) and LV ejection fraction (LVEF) (63 ± 13 vs 66 ± 4% P = 0.17) between the two groups. In HCM, GCW was the only predictor of LV fibrosis at multivariable analysis (OR 1.01, 95% CI: 0.99–1.08, P = 0.04). A cutoff value of 1623 mm Hg% (AUC 0.80, 95% CI: 0.66–0.93, P < 0.0001) was able to predict myocardial fibrosis with a good sensitivity and fair specificity (82% and 67%, respectively). Conclusions Global constructive work is significantly reduced in HCM despite normal LVEF and is associated with the LV fibrosis as assessed by LGE.

Classification of PMR can be improved using statistical learning algorithms to define therapeutically homogeneous patient subclasses. High-risk patients can be identified, and these patients should be carefully monitored and may even be treated earlier.