Ventricular volume asymmetry as a novel imaging biomarker for disease discrimination and outcome prediction

Disruption of the predictable symmetry of the healthy heart may be an indicator of cardiovascular risk. This study defines the population distribution of ventricular asymmetry and its relationships across a range of prevalent and incident cardiorespiratory diseases. The analysis includes 44,796 UK Biobank participants (average age 64.1±7.7 years; 51.9% women). Cardiovascular magnetic resonance (CMR) metrics were derived using previously validated automated pipelines. Ventricular asymmetry was expressed as the ratio of left and right ventricular (LV, RV) end-diastolic volumes. Clinical outcomes were defined through linked health records. Incident events were those occurring for the first time after imaging, longitudinally tracked over an average follow-up time of 4.75 ± 1.52 years. The normal range for ventricular symmetry was defined in a healthy subset. Participants with values outside the 5th-95th percentiles of the healthy distribution were classed as either LV dominant (LV/RV > 112%) or RV dominant (LV/RV < 80%) asymmetry. Associations of LV and RV dominant asymmetry with vascular risk factors, CMR features, and prevalent and incident cardiovascular diseases were examined using regression models, adjusting for vascular risk factors, prevalent diseases, and conventional CMR measures. LV-dominance was linked to an array of pre-existing vascular risk factors and cardiovascular diseases, and a two-fold increased risk of incident heart failure, non-ischemic cardiomyopathies, and left-sided valvular disorders. RV dominance was associated with an elevated risk of all-cause mortality. Ventricular asymmetry has clinical utility for cardiovascular risk assessment, providing information that is incremental to traditional risk factors and conventional CMR metrics.