Disparities in quantification of mitral valve regurgitation between cardiovascular magnetic resonance imaging and trans-thoracic echocardiography: a systematic review

Primary mitral regurgitation (MR) is a prevalent valvular heart disease. Therapy stratification for MR depends on accurate assessment of MR severity and left ventricular (LV) dimensions. While trans-thoracic echocardiography (TTE) has been the standard/preferred assessment method, cardiovascular magnetic resonance imaging (CMR) has gained recognition for its superior assessment of LV dimensions and MR severity. Both imaging modalities have their own advantages and limitation for therapy guidance. However, the differences between the two modalities for assessing/grade severity and clinical impact of MR remains unclear. This systematic review aims to evaluate the differences between TTE and CMR in quantifying MR severity and LV dimensions, providing insights for optimal clinical management. A literature search was performed from inception up to March 21st 2023. This resulted in 2,728 articles. After screening, 22 articles were deemed eligible for inclusion in the meta-analysis. The included study variables were, mitral valve regurgitation volume (MR VOL ), regurgitation fraction (MR FRAC ), LV end-diastolic volume (LVEDV), LV end-systolic volume (LVESV), LV stroke volume (LVSV), and LV ejection fraction (LVEF). TTE showed a significant higher MR VOL (10.4 ml, I 2 = 88%, p = 0.002) and MR FRAC (6.3%, I 2 = 51%, p = 0.05) compared to CMR, while CMR demonstrated a higher LVEDV (21.9 ml, I 2 = 66%, p = < 0.001) and LVESV (16.8 ml, I 2 = 0%, p = < 0.001) compared to TTE. Our findings demonstrate substantial disparities in TTE and CMR derived measurements for parameters that play a pivotal role in the clinical stratification guidelines. This discrepancy prompts a critical question regarding the prognostic value of both imaging modalities, which warrants future research.