Clinical Bottom Line: ANTICOAGULATION for DVT and PE

What we know:

Two small RCT’s have tested anticoagulation for acute VTE. The first was stopped too early to be valid (n=35), and was performed on ill inpatients. The PE diagnosis was often unconfirmed. The second trial compared anticoagulation to an NSAID for ambulatory DVT patients. The trial was open label, lacked power analysis, and enrolled 90 subjects.

The only RCT of submassive PE was also truncated inappropriately, but reported that heparin + thrombolytics reduced ‘death or escalation of treatment’ by 15% compared to heparin + placebo. Mortality was unaffected therefore ‘escalation’ (i.e. rescue thrombolysis) was the difference. Criteria for escalation were subjective, and few patients became critically ill at any point. There was no bleeding difference.

What we think:

The first study of anticoagulation for VTE is neither valid nor reliable, but implies that very ill inpatients with clinical PE may potentially benefit from anticoagulation. The second trial was imperfect but far more valid, and implies no benefit to anticoagulation for ambulatory DVT patients. It seems clear that high quality trials comparing anticoagulation to a control group are needed. Current treatment standards are opinion-based, not evidence-based.

Treatment of submassive PE with thrombolytics remains open. The existing trial, due to inappropriate early stoppage, neither proves nor disproves a patient-oriented benefit.  

What we recommend:

1) The existence of a ‘standard of care’ for VTE treatment is misguided; high quality studies are needed.

2) For ill inpatients with clinically obvious PE anticoagulation is reasonable but lacks a strong evidence base.

3) For well, ambulatory VTE patients it is evidence-based to note a lack of benefit to anticoagulation in the lone trial. While an expectant approach to calf DVT is accepted and common, the ‘standard of care’ for proximal DVT is anticoagulation. It is possible to discuss and consider the evidence with patients, though in our community ‘expert’ opinion may well trump evidence in a court of law.

4) The use of lytics for submassive PE is a grey area, and completed, high quality studies are also needed.