Left-to-Right Chamber Volume Ratios at Cardiac MRI Predict Cardiac Events: A Multi-Ethnic Study of Atherosclerosis Secondary Analysis

Background The clinical significance of relative left-to-right chamber volume imbalances, even when individual chamber volumes are within "normal" ranges, remains inadequately established. Purpose To assess whether volumetric imbalance between the left and right ventricles and atria assessed with cardiac MRI is associated with cardiac events in individuals without cardiovascular disease (CVD) history. Materials and Methods This secondary analysis of the Multi-Ethnic Study of Atherosclerosis (MESA) included participants free of CVD at baseline (July 2000-July 2002) who underwent cardiac MRI. The left-to-right ventricular volume ratio (LRVR) was defined at end diastole, whereas the left-to-right atrial volume ratio (LARA) was defined at end systole. LRVR was categorized into balanced (0.8-1.3), low (<0.8), and high (>1.3), whereas LARA was classified into low (≤2) and high (>2). Cox regression models were used to examine the associations of LRVR and LARA with heart failure (HF), atrial fibrillation (AF), and death, adjusting for traditional risk factors. Abnormal chamber volume was defined as indexed volume of more than 95% or less than 5% sex-specific percentile. Results A total of 4073 MESA participants were included (mean age, 61.3 years ± 10 [SD], 2133 females); in the follow-up, 239 (5.9%) developed HF, 772 (19.0%) developed AF, and 906 (22.2%) died. A high LRVR was associated with increased risk of HF (hazard ratio [HR], 2.54; <i>P</i> < .001), AF (HR, 1.57; <i>P</i> = .001), and death (HR, 1.62; <i>P</i> < .001) compared with a balanced LRVR. A low LRVR was not significantly associated with events. In those with normal right ventricle and left ventricle volumes, high LRVR still predicted HF (HR, 1.99; <i>P</i> = .04), AF (HR, 1.55; <i>P</i> = .04), and death (HR, 1.57; <i>P</i> = .02). High LARA was predictive of HF (HR, 1.99; <i>P</i> < .001) and AF (HR, 1.41; <i>P</i> < .001) after full adjustment, particularly influencing outcomes in participants with an LRVR of less than 1.3. Conclusion In participants without a history of CVD, elevated left-to-right ventricular and atrial volumes predicted HF, AF, and death, compared with balanced left-to-right chamber volumes. ClinicalTrials.gov: NCT00005487 © RSNA, 2025 <i>Supplemental material is available for this article.</i> See also the editorial by Cadour and Dacher in this issue.