Pseudonormalization of global myocardial work index and global constructive work, but not global wasted work, in patients with obstructive hypertrophic cardiomyopathy

Background/objectives Hypertrophic cardiomyopathy (HCM) is a genetic cardiac disorder characterized by left ventricular hypertrophy, often leading to diastolic dysfunction and, in some cases, dynamic outflow tract obstruction. In recent years, myocardial work (MW) parameters, derived from novel echocardiographic techniques, have emerged as sophisticated indices for the quantitative assessment of systolic myocardial contractile function. The present study sought to elucidate the intricate interrelationships among these MW parameters and to delineate their differential characteristics in patients presenting with non-obstructive versus obstructive HCM. Methods The present study enrolled 118 patients with HCM [77 men (65%), mean age: 53±13 years], including 68 non- obstructive (nHCM) and 50 obstructive (oHCM) patients. In all cases a comprehensive echocardiography has been performed, inculding global longitudinal strain (GLS) and derived MW parameters (global work index (GWI), global constructive work (GCW), global wasted work (GWW), and global work efficiency (GWE). The patients were further classified into subgroups according to of the left ventricular outflow tract (LVOT) gradient: <10 Hgmm, <30 Hgmm, >30 Hgmm, >50 Hgmm and >70 Hgmm. Results GLS values decreased gradually (from -15.1 to -14.2%) as LVOT gradients increased. This difference compared to controls was significant even in the HCM group with LVOT gradients <10 mmHg (-20.0 vs. -15.1%, p=0.000). Conversely, peak LVOT resting gradient values increased gradually (from 0 mmHg to 99 mmHg) with increasing LVOT gradient categories, and the difference compared to controls was significant in all HCM groups. Systolic BP was not different between the categories, so MW parameters were defined by almost entirely by the GLS and resting gradient. Importantly, the difference between GWI or GCW values in controls and HCM subgroups with increasing LVOT gradients was significant only in the non-obstructive HCM group (with LVOT gradients <10 mmHg or <30 mmHg). In the obstructive HCM groups, this difference disappeared, even in the HCM group with LVOT gradients >30 mmHg. In contrast, GWW values increased gradually (from 210 to 364 mmHg%) with increasing LVOT gradients, and the difference compared to controls was significant even in the HCM group with LVOT gradients <10 mmHg (121 vs. 210 mmHg%, p=0.044). Similar changes were observed regarding GWE values, exhibiting the opposite trend, decreasing gradually (from 88 to 85%) with rising LVOT gradients. The difference compared to controls was also significant even in the HCM group with LVOT gradients <10 mmHg (95 vs. 88%, p=0.000). Conclusion The observed change of GWI and GCW showed a „pseudonormalization" pattern which was primarily attributable to the offsetting effects of the nominal decrease in GLS values and the nominal increase in resting LVOT gradient values. GWW and GWE were more informative due to their relaitve independence of GLS.