Abstract
Aim: To evaluate the prognostic utility of red blood cell distribution width (RDW) and left ventricular mass index (LVMI) in patients with hypertrophic cardiomyopathy (HCM).
Patients & methods: This study is a retrospective cohort analysis. Patients diagnosed with hypertrophic cardiomyopathy at the First Affiliated Hospital of Sun Yat-sen University from March 2014 to March 2019 were included . HCM patients were stratified into two groups based on the occurrence of major adverse cardiac events (MACE).Receiver operator characteristic (ROC) curves were then constructed and Cox regression models were employed to gauge the prognostic relevance of RDW and LVMI for HCM patients. Kaplan-Meier analysis evaluated the survival and MACE-free rate in patients with different level of RDW and LVMI.
Results: A total of 300 patients with HCM were enrolled in this study and followed up for 40.56±18.33 months. Among them, 117 MACE (39.00%), 40 all-cause deaths (13.33%), 29 cardiovascular deaths (9.67%). The level of RDW, LVMI, creatinine (Cr) and B-type pro-brain natriuretic peptide (NT-ProBNP) were statistically different between the MACE group and Non-MACE group (P <0.05). Multivariate analysis showed that after adjusting for confounding factors, RDW and LVMI were independent predictors of all-cause mortality and MACE in HCM patients. ROC showed that RDW>0.13 and LVMI>181g/m2 are the cut-off value to predict all-cause mortality and MACE. The AUC of the combination predicting the occurrence of all-cause mortality and MACE are 0.890 and 0.885 respectively. Kaplan-Meier analysis showed that the survival rate and MACE-free survival rate of group 1 (RDW≦0.13 and LVMI≦181g/m2) were significantly higher than group 2 (RDW>0.13 or LVMI>181g/m2), and group 3 (RDW >0.13 and LVMI>181g/m2) (P =0.000).
Conclusion: We determined that increased RDW and LVMI was independently associated with MACE incidence and risk of mortality in HCM patients. Combined evaluation of RDW and LVMI yielded a more accurate predictive model of HCM patient outcomes relative to the use of either of these metrics in isolation. Our research can provide a theoretical basis in the occurrence of MACE for the high-risk HCM and intervene them properly and timely.
Keywords: hypertrophic cardiomyopathy, red blood cell distribution, left ventricular mass index.
Introduction
Hypertrophic cardiomyopathy (HCM) is among the most prevalent forms of heritable cardiomyopathy, affecting between 1/200 and 1/500 of the overall general population. Treatment of HCM is generally ineffective, and the condition tends to steadily progress, ultimately resulting in the premature death of affected individuals [1-3]. While HCM affects both males and females equally and has been observed in diverse global populations, its clinical manifestations can vary substantially, ranging from asymptomatic cases to instances of sudden cardiac death (SCD) [2]. While SCD is a relatively rare outcome affecting < 1% of HCM patients per year, it is a particularly salient and concerning risk in those affected by this condition [3], particularly owing to the frequent coverage by the media of episodes of sudden cardiac arrest in competitive athletes [2] and to the difficulty of predicting SCD risk in those with HCM [4]. Several recent studies have sought to develop reliable approaches to identifying adults at an elevated risk of SCM. Known risk factors for HCM detected through these prior efforts have included family history of premature sudden death [5], unexplained syncope [6], non-sustained ventricular tachycardia (NSVT) [7], atypical changes in blood pressure during exercise (either a failure to rise by at least 20 mmHg or a reduction by at least 20 mmHg during exertion) [8], and severe left ventricular hypertrophy (≥30mm) [9]. While all of these predictors have been shown to exhibit a high negative predictive value (≥90%), they typically exhibit poor positive predictive value (15-20%) [10]. It is thus urgent that novel approaches to reliably identifying predictors of HCM be identified in order to guide patient education and treatment as appropriate.
HCM is associated with a significant increase in cardiac mass, contributing to SCD, arrhythmias, and adverse left ventricular (LV) remodeling [11]. Left ventricular mass (LVM) in particular is linked to tissue fibrosis, and can be used to assess the overall degree of LV hypertrophy better than many other parameters, as hypertrophy patterns are often highly variable in regions distant from the maximal LV thickness [12]. Developments in echocardiographic technologies have clearly emphasized the utility of LVM in the management of HCM and associated cardiac hypertrophy, with LVM being negatively correlated with cardiovascular outcomes in both the general population and in those with hypertension/aortic stenosis [13], serving as an independent predictor of cardiovascular risk [14].
Red blood cell distribution width (RDW) is a parameter that can be measured through routine complete blood counts, assessing the overall variability of red blood cell (RBC) size distributions in a given individual [15]. Historically, RDW has primarily been monitored in the context of anemia differential diagnosis [16]. However, some studies have recently reported a strong independent relationship between RDW and adverse outcomes in patients with pulmonary arterial hypertension [17], coronary disease [16], and heart failure [18]. The prognostic relevance of RDW in HCM patients, however, remains to be studied in depth. In one analysis, baseline RDW was shown to be positively associated with heart failure incidence in HCM patients without a history of such failure [19]. The relationship between RDW and other negative outcomes including cardiac death and mortality is unclear at present. As such, this study was conducted to evaluate the relevance of RDW and LVMI alone and in combination as predictors of negative cardiac outcomes and all-cause death in HCM patients.
Patients & Methods