Adverse Remodeling and Fibrosis Predict Outcomes in Excessive Trabeculation of the Left Ventricle: A Multiparametric CMR Risk Score.
Abstract
Background
Excessive trabeculation of the left ventricle (ETLV) is a heterogeneous and controversial phenotype that overlaps with both physiological remodeling and cardiomyopathy.
Objectives
This study sought to develop and validate a cardiac magnetic resonance (CMR)-based model to predict major adverse cardiovascular events (MACE) and to assess the incremental prognostic value of trabeculation metrics.
Methods
In this international retrospective study, 589 patients with ETLV across 17 centers underwent core-laboratory CMR analysis. The composite MACE endpoint included heart failure, ventricular arrhythmia, systemic embolism, or all-cause death. A prediction model was derived from morphofunctional CMR parameters and validated in an independent cohort. The incremental value of trabeculation indices was then assessed. Outcomes were further compared with a propensity-matched cohort of 197 patients with dilated cardiomyopathy.
Results
Mean age was 43 ± 18 years, 43% were women, mean left ventricular (LV) ejection fraction was 48% ± 14%, and 12% had late gadolinium enhancement (LGE). Over a median follow-up of 3.6 years, 121 (21%) patients experienced MACE. A model including indexed LV end-diastolic volume, LV global longitudinal strain, and LGE extent demonstrated moderate prognostic performance (C-statistic 0.77 in derivation; 0.70 in validation) and calibration. Addition of trabeculated mass percentage (TM%) modestly improved discrimination (C-statistic 0.79 in derivation, P = 0.012; 0.72 in validation); an exploratory TM% ≥28% identified higher-risk patients. However, TM% was not predictive among individuals with normal indexed LV end-diastolic volume, preserved LV global longitudinal strain, and minimal LGE, who exhibited excellent outcomes. Prognosis was comparable in propensity-matched ETLV and dilated cardiomyopathy cohorts (P = 0.557).
Conclusions
CMR-based risk stratification in ETLV is primarily driven by adverse LV remodeling and fibrosis, whereas trabeculation indices provide only modest incremental prognostic value. In the absence of high-risk imaging features, ETLV likely represents a benign morphologic trait. This pragmatic multiparametric CMR score may support clinical decision-making in this debated phenotype.