Diagnostic and Prognostic Value of RV Strain Defined as RV/LV Ratio on Chest CT in Acute Pulmonary Embolism: A Systematic Review

Background

Pulmonary embolism (PE) is a common cause of acute RV enlargement (often described as RV strain or RV-S), with significant associated mortality and morbidity. Chest CT pulmonary angiography is a widely available diagnostic modality to rule out PE and assess for RV-S, if positive for PE. Frequently, RV-S is assessed by measuring the right ventricular (RV) to left ventricular (LV) ratio (RV/LV ratio); however, there is no standardized technique for measuring CT RV/LV ratio, and the prognostic value of this marker is not well-defined.

Methods

PubMed and EMBASE databases were searched from inception to December 2023. A total of 35 studies were eligible for data collection based on relevance, completeness, and quality of data.

Results

The most common clinically effective cutoffs of the RV/LV ratio used were 0.9 and 1.0, and the most common methodology involved measuring RV and LV diameters within the same axial slice on both 2D (axial) and reconstructed 4-Chamber (4-Ch) views. Although 4-Ch and axial views had different RV/LV ratio predictability regarding specific outcomes such as 30-day death, there was no significant overall difference in the prognostic value across the different cutoffs used.

Conclusions

Our study demonstrates a lack of definite standardization in measuring CT RV/LV ratio in acute PE. Based on our review, we propose an RV strain defined as CT RV/LV ratio >1.0 measured on a single axial CT slice as an easily measurable and reliable marker of RV dysfunction in acute PE, with associated significant prognostic value in predicting adverse outcomes.