Right-to-left ventricular ratio is higher in systole than diastole in patients with acute pulmonary embolism.

Objectives: In acute pulmonary embolism (PE), the right ventricle (RV) may dilate compromising left ventricular (LV) size, thereby increasing RV/LV ratio. End-diastolic RV/LV ratio is often used in PE risk stratification, though the cause of death is RV systolic failure. We aimed to confirm our pre-clinical observations of higher RV/LV ratio in systole compared to diastole in human patients with PE.

Methods: We blinded and independently analyzed echocardiograms from 606 patients with PE, evaluated by a Pulmonary Embolism Response Team. We measured RV/LV ratios in end-systole and end-diastole and fractional area change (FAC). Our primary outcome was a composite of 7-day clinical deterioration, treatment escalation or death. Secondary outcomes were 7-day and 30-day all-cause mortality.

Results: RV/LV ratio was higher in systole compared to diastole (median 1.010 [.812-1.256] vs. .975 [.843-1.149], p < .0001). RV/LV in systole and diastole were correlated (slope = 1.30 [95% CI 1.25-1.35], p < .0001 vs. slope = 1). RV/LV ratios in both systole and diastole were associated with the primary composite outcome but not with all-cause mortality.

Conclusion: The RV/LV ratio is higher when measured in systole versus in diastole in patients with acute PE. The two approaches had similar associations with clinical outcomes, that is, it appears reasonable to measure RV/LV ratio in diastole.