Myocardial Contraction Fraction as a Simple Marker of Disease Severity in Hypertrophic Cardiomyopathy

Abstract

Purpose: Myocardial contraction fraction (MCF) of cardiac magnetic resonance (CMR) was used to evaluate myocardial function in patients with hypertrophic cardiomyopathy (HCM), which may represent a proxy marker of disease severity in HCM. Materials and Methods: A total of 60 HCM patients and 20 healthy controls were examined with CMR. MCF was calculated by dividing left ventricular stroke volume by left ventricular myocardial volume. The difference in MCF between late gadolinium enhancement (LGE)-positive and LGE-negative patients were compared. The differences in MCF were compared among patients with stages Ⅱ, Ⅲ, and Ⅳ of HCM. Logistic regression analysis was used to detect independent discriminants of more severe HCM. Receiver operating characteristic analysis differentiated HCM with different clinical stages. Results: Compared with controls (110.67±20.40%, P<0.001), values for MCF were significantly reduced in HCM (61.40±15.60%). The MCF reduction in LGE detected by CMR was more significant than in HCM patients without LGE (53.15±10.67% vs. 76.72±11.04%, P<0.001). Patients with stage IV of HCM had the lowest MCF (45.36±10.97%, P<0.05 vs. stage II and III). Lower MCF remains an independent discriminator for more severe HCM (Stage Ⅱ vs. Stage Ⅲ, odds ratio: 0.85; Stage Ⅲ vs. Stage Ⅳ, odds ratio: 0.88, all P<0.05). The optimal cutoff value for detecting more severe HCM is MCF under 66.40% (Stage Ⅱ vs. Stage Ⅲ, P<0.05) and 44.75% (Stage Ⅲ vs. Stage Ⅳ, P<0.05). Conclusion: MCF may be a useful and simple tool to evaluate myocardial function in patients with HCM and provide an indicator of disease severity in individuals with HCM.