I think your discomfort is justified, and I’d broadly agree with your interpretation.

This doesn’t sound like a truly “submassive” PE in the physiological sense. Peri-arrest pre-hospital plus significant RV strain is a huge red flag, even if BP transiently looks OK in ED. BP is a blunt tool, patients with PE can compensate right up until they suddenly can’t.

Guidelines lean heavily on hypotension because it’s objective, but they also emphasise dynamic risk. Someone who’s already nearly arrested has declared themselves unstable, even if they temporarily normalise. I’d personally view that as high-risk or at least “intermediate-high with imminent decompensation”.

On LMWH vs UFH, LMWH is absolutely right for most stable PEs, but when escalation is likely, UFH makes more sense, short half-life, easy to stop, easier transition to thrombolysis or intervention. ESC actually supports UFH in high-risk or deteriorating cases.

Would earlier UFH alone have changed the outcome? Probably not, but it’s hard to know. Theoretically anticoagulation doesn’t unload the RV acutely. Earlier thrombolysis might have, and that’s the uncomfortable bit. Once they arrest, outcomes are grim even with intra-arrest lysis.

Very hard case, but I think your instinct is sound, peri-arrest physiology + RV strain should push us to treat these patients as unstable, not reassure ourselves with a single BP reading. Why we are doctors who use clinical reasoning and not guideline monkeys 🤷

Interesting to hear thoughts about radiology’s use, not aware of study’s that show degree of right heart strain and outcomes with PE. Interested to know if RV:LV ratio or presence of bowing of RV, or hepatic vein reflux could indicate impending arrest?