For patients with newly diagnosed VTE on IV heparin planned for transition to DOAC, would you start at the loading or maintenance DOAC dose?  

Agree with Dr. @Tapson. In the clinical trials that led to rivaroxaban and apixaban approval, many patients had 2 days of injected anticoagulant first to arrive at successful outcomes leading to DOAC approval. I suggest IV heparin until hemodynamically normal (for PE), sq LMWH for a dose or two for ...

No solid data. Still, I always go to full dose DOAC regimen unless the bleeding risk is high.

Enoxaparin upfront unless there is a bad renal failure, and then start a regular loading schedule for the DOAC. Unlikely, they’ve been therapeutic the full time they were on heparin, so I would not count/trust those days anyway.

While the packaging guidelines recommend a seven-day loading dose (regardless of prior heparin/enoxaparin), in my experience, many people do a shorter loading duration after being on heparin/enoxaparin. I think the above comments about the heparin often not being therapeutic definitely should factor...

Prefer LMWH > UFW, but then begin loading dose of DOAC and d/c LMWH or UFW.