VOLUMETRIC imbalances between the left and right chambers of the heart may have clinical significance even when individual chamber sizes fall within normal reference ranges. A recent study investigated whether such asymmetries, specifically elevated left-to-right volume ratios in the ventricles and atria, can predict future cardiac events in people without known cardiovascular disease (CVD). A key finding from this large cohort analysis is that individuals with a left-to-right ventricular volume ratio (LRVR) greater than 1.3 had a significantly increased risk of heart failure, atrial fibrillation, and mortality.
The study was a secondary analysis of the Multi-Ethnic Study of Atherosclerosis (MESA), which included 4073 adults without prior CVD who underwent cardiac MRI between 2000 and 2002. Researchers assessed the LRVR at end diastole and the left-to-right atrial volume ratio (LARA) at end systole. Participants were stratified into balanced, low, and high LRVR groups, and into low and high LARA categories. Cox regression models adjusted for standard cardiovascular risk factors were used to evaluate the associations between chamber volume ratios and incident heart failure (HF), atrial fibrillation (AF), and death. Analyses were also performed in subgroups with “normal” individual chamber volumes to determine the impact of volume ratio independent of absolute size.
During the follow-up period, 5.9% of participants developed HF, 19.0% developed AF, and 22.2% died. A high LRVR (>1.3) was associated with significantly increased risk of HF (hazard ratio [HR]: 2.54; p<0.001), AF (HR: 1.57; p=0.001), and death (HR: 1.62; p<0.001), compared with balanced ratios. Importantly, even among individuals whose left and right ventricular volumes were both within normal limits, a high LRVR still conferred elevated risk of HF (HR: 1.99; p=0.04), AF (HR: 1.55; p=0.04), and death (HR: 1.57; p=0.02). High LARA (>2) was also predictive of HF (HR: 1.99; p<0.001) and AF (HR: 1.41; p<0.001), particularly among participants with LRVR values below 1.3.
These findings suggest that chamber volume asymmetry, particularly a high left-to-right ventricular or atrial ratio, may serve as an early imaging biomarker of cardiovascular risk. While the study is limited by its observational design and older imaging data, the results highlight the potential value of incorporating volume ratio assessment into cardiac MRI interpretation, even when chamber sizes appear normal. This may aid in identifying at-risk individuals who might otherwise go undetected in clinical practice.
Reference
Hoballah M et al. Left-to-Right Chamber Volume Ratios at Cardiac MRI Predict Cardiac Events: A Multi-Ethnic Study of Atherosclerosis Secondary Analysis. Radiology. 2025;316(2):e243462.
