Submassive vs massive PE: this is an old classification that isn’t helpful anymore.
“Submassive” means low to intermediate risk, hemodynamically stable patient with no standard for how big or little the clot is.
“Massive” means high-risk, hemodynamically unstable, and again, no standard for how big or little the clot is.
We freak out about saddle emboli, but a saddle embolus isn’t necessarily high-risk. What is concerning? Elevated troponins or BNP, or signs of RV strain on the ECHO. You may even see RV strain on CT if the ventricle is larger or the septum is bulging inversely; reflux of hepatic contrast indicates that RV filling pressures are higher.
What to do with high-risk patients? Consider giving TPA. This shouldn’t be a knee-jerk reaction due to possible bleeding risk. That being said, there is some evidence such as the PEITHO trial showing that TPA might have a role in intermediate-risk PEs as well.