The prognostic role of novel echocardiographic global functional indexes in hypertrophic cardiomyopathy

Hypertrophic cardiomyopathy (HCM) is characterized by impaired systolic and diastolic myocardial function. Despite left ventricular ejection fraction (LVEF), global longitudinal strain (GLS), early peak transmitral flow velocity to early diastolic myocardial velocity (E/e’) ratio and left atrium (LA) markers are extensively used in the evaluation of HCM, they separately evaluate systolic or diastolic function. The global functional index is the ratio of E/e’ ratio divided by S’, the peak systolic myocardial velocity (E/e’/S’), and allows global analysis of the left ventricle’s (LV) function. Since the S’ parameter measures regional wall systolic motion, we also calculated a modified GFI that, instead of S' as a denominator, GLS was used, and the product was multiplied by 10.

We investigated classic and modified GFI in HCM and their association with markers of myocardial damage and the development of arrhythmias and heart failure with LVEF<50%.

We prospectively studied consecutive patients diagnosed with HCM via echocardiography at our medical center between 2017 and 2024. To calculate the LV mass index (LVMi), LA volume index (LAVi), LA reservoir (LAr) strain LVEF, E/e’ ratio, S ', and GLS, 2D echocardiography, pulse-wave Doppler, tissue Doppler imaging, and speckle tracking were performed. A 48-hour ECG recording assessed the presence of non-sustained ventricular tachycardia (NSVT). Blood samples were collected on the same day with echo, and high-sensitive troponin I (TnI), c-reactive protein (CRP), and brain natriuretic peptide (BNP) were measured. Statistical analysis was performed using the SPSS software.

Forty-six patients with HCM were studied; their mean age was 50 years, while 78% (36/46) were male. During the study, 45% (21/26) had NSVT, and 20% (9/46) progressed to the burnout HCM phase. Classic GFI had a significant positive association with LVMi (r=0.385, p=0.008), TnI (r=0.521, p<0.001), BNP (r=0.498, p=0<001), CRP (r=0.350, p=0.017), the development of burnout-HCM (r=0.323, p=0.029) and a significant negative association (LAr strain (r=-0.428, p=0.003). On the other hand, modified GFI had a more strong correlation with LVMi (r=0.530, p<0.001), LAr strain (r=-0.496, p<0.001), TnI (r=0.617, p<0.001), BNP (r=0.546 p<0.001), CRP (r=0.384, p=0.008 (r=0.328, p=0.026), burnout HCM progression (r=0.383, p=0.009), than classic GFI as well as more significant associations with LAVi (r=0,312, p=0.035) and the development of NSVT (r=0.328, p=0.026).

GFIs are novel, promising echocardiographic markers in HCM that evaluate the systolic and diastolic LV function globally. Modified GFI has a stronger association with myocardial damage, LV hypertrophy, and diastolic dysfunction than classic and can better predict NSVT and the burn-out phase.