First‐Phase Ejection Fraction: A Novel Approach to Detecting Early Systolic Dysfunction in Hypertrophic Cardiomyopathy

BACKGROUND: The assessment of stable coronary artery disease has been performed using the first-phase ejection fraction (EF1) in previous research. However, the use of EF1 has seldom been employed in the evaluation of early left ventricular systolic dysfunction among patients with hypertrophic cardiomyopathy (HCM). OBJECTIVE: We aimed to assess early left ventricular systolic dysfunction in patients with HCM by application of first-phase EF1. METHODS: The cohort included 90 HCM patients who were stratified according to pathophysiological subtype into 50 with nonobstructive (NO-HOCM) and 40 with obstructive (HOCM) disease. An additional 50 age-matched healthy individuals served as controls. Baseline characteristics, conventional echocardiographic parameters, EF1 were measured and serum B-type natriuretic (BNP) peptide was detected. Additionally, the correlations between EF1 and both LVMI and BNP were compared, and receiver operating characteristic (ROC) curve analysis was performed to calculate the area under the curve (AUC) for assessing the value of EF1 in the early detection of left ventricular systolic dysfunction in HCM patients. RESULTS: Compared to the control group, patients with HOCM showed higher systolic blood pressure and lower heart rate (p < 0.05). Both HOCM and NO-HCM showed enlarged LAD and LVDd, elevated LVMI, LVEF, E/e' ratios and BNP compared with controls (p < 0.05). However, EF1 was decreased in HCM patients than that in controls (38.20 ± 2.02, P < 0.05), especially in HOCM patients (22.29 ± 3.59 & 25.12 ± 3.19, P < 0 .05). EF1 was negatively correlated with both LVMI and BNP (all r > 0.3, P < 0.001). Receiver operating characteristic (ROC) curve analysis demonstrated that EF 1 (AUC = 0.874) exhibited superior diagnostic value for assessing early left ventricular systolic dysfunction in patients with HCM compared with LVEF (AUC = 0.649). The optimal cut-off value for EF1 was < 28.5%, with a sensitivity of 90.6% and a specificity of 81.5%, corresponding to an AUC of 0.874 (95% CI: 0.804-0.946, p < 0.001). CONCLUSION: Compared with healthy controls, patients with HCM had a lower EF1, and this reduction was significantly more pronounced in those with HOCM. Given its high sensitivity in evaluating left ventricular systolic function in patients with HCM, EF1 represents a promising adjunctive parameter for the multimodal assessment of systolic function in this population.