Interrelationship between the Myocardial Mass, Fibrosis, BNP, and Clinical Outcomes in Hypertrophic Cardiomyopathy

Abstract Objective Increased left ventricular mass (LVM) and LV fibrosis mass (LVFM) are characteristics of hypertrophic cardiomyopathy (HCM). Additionally, a substantial increase in the plasma B-type natriuretic peptide (BNP) level is observed. Therefore, we investigated the interrelationship and clinical significances of these parameters in a HCM cohort that underwent cardiac MRI (CMR). Methods Patients with HCM (n=109) receiving regular outpatient treatment underwent CMR and follow-up through 2015 from CMR examinations. The clinical outcome measures were all-cause mortality, admission for worsening heart failure, and ventricular tachycardia/fibrillation. Results The baseline body mass index (BMI), LV outflow tract (LVOT) obstruction, New York Heart Association (NYHA) class, and increased left atrial dimension (LAD) index were associated with the plasma BNP level. In the CMR analysis, LVM and LVFM indices significantly correlated with the BNP level (r=0.422 and 0.368, respectively), which were independent determinants according to a multivariate analysis (p=0.009 and 0.023, respectively). A Kaplan-Meier analysis during a median follow-up of 19.4 months showed that the baseline LVM or LVFM index was not associated with the clinical outcomes. However, the baseline BNP level was significantly associated with them (p<0.001). In addition, a multivariate Cox proportional hazard analysis showed that plasma BNP was an independent predictor for the clinical outcomes after adjusting for age, sex, LVM, and LVFM. Conclusion The LVM and LVFM are determinants of the BNP level independent of the BMI, LVOT obstruction, LAD, and NYHA class in patients with HCM. However, plasma BNP may be a more sensitive integrated-marker for the clinical outcomes than LVM or LVFM.