ABLE-SCORE: a simplified risk score for major adverse cardiovascular outcomes in patients with left ventricular noncompaction
Authors: Liu L , Li T , Zeng R , Cai S , Chen A , Dong Y , Zhou L , Xu M , Li L , Li Y , Lu M , Zheng L , Ding L , Yao Y 
Published: October 2024

Abstract

Background
Left ventricular noncompaction (LVNC) is a heterogeneous entity with life-threatening complications and variable prognosis [1,2]. However, there are limited prediction models available to identify individuals at high risk of adverse outcomes, and the current risk score in LVNC is comparatively complex for clinical practice [3,4].

Purpose
To develop and validate a simplified risk score to predict major adverse cardiovascular events (MACE) in LVNC.

Methods
This multicenter longitudinal cohort study consecutively enrolled morphologically diagnosed LVNC patients between January 2009 and December 2020 at a single national-level medical center (derivation cohort n=300; internal validation cohort n=129), and between January 2014 and December 2022 at two national-level medical centers (external validation cohort n=95). The derivation/internal validation cohorts and the multicenter external validation cohort were followed annually until December 2022 and December 2023, respectively. MACE was defined as a composite of all-cause mortality, heart transplantation/left ventricular assist device implantation, cardiac resynchronization therapy, malignant ventricular arrhythmia, and thromboembolism. A simplified risk score, the ABLE-SCORE, was developed based on independent risk factors for MACE in the multivariable Cox regression predictive model, and underwent both internal and external validation to confirm its discrimination (Harrell’s C-index), calibration (calibration plots), and clinical applicability (decision curve analysis).

Results
A total of 524 LVNC patients (43.5 ± 16.6 years, 65.8% male) were included in the study. At the end of the follow-up, 97 (32.3%), 38 (29.5%), and 20 (21.1%) individuals in the derivation, internal validation, and external validation cohort experienced at least one endpoint of MACE. The ABLE-SCORE was established using four easily accessible clinical variables: age at diagnosis, N-terminal pro-brain natriuretic peptide levels, left atrium enlargement and left ventricular ejection fraction≤40% measured by echocardiography. The risk score showed excellent performance in discrimination, with Harrell’s C-index of 0.821 (95%CI 0.772-0.869), 0.786 (95%CI 0.703-0.869), and 0.750 (95%CI 0.644-0.856) in the derivation, internal validation, and external validation cohort, respectively. Calibration plots of the three datasets suggested accurate agreement between the predicted and observed 5-year risk of MACE in LVNC. According to decision curve analysis, the ABLE-SCORE displayed greater net benefit than the currently existing risk score for MACE in LVNC [3], indicating its strength in clinical applicability.

Conclusions
Derived from readily available laboratory and echocardiographic variables, a simplified and efficient risk score for MACE was developed and validated using a large LVNC cohort, making it a reliable and convenient tool for the risk stratification and clinical management of patients with LVNC.Development of the ABLE-SCOREValidation of the ABLE-SCORE