CARDIOLOGY ESSENTIALS: Deep Vein Thrombosis

 meritmedscript.blogspot.com  ·  Clinical exam notes  ·  October 2026

CARDIOLOGY ESSENTIALS: Deep Vein Thrombosis

Proximal iliofemoral thrombus is a valve-saving question, not only an anticoagulation question.

Cancer-associated isolated distal DVT is not a 3-month problem.

Lytic-free thrombectomy has registry support. It does not yet have a completed randomised result against anticoagulation.

Established iliac-vein obstruction with moderate or severe PTS can be reconstructed. Bleeding rises.

Part 1. What has actually changed

Four data sets are in use. Only two change a present decision. ONCO DVT is a completed randomised trial.

C-TRACT reported in April 2026. CLOUT is a registry, not a control arm. DEFIANCE is still recruiting, with primary completion estimated in 2028.

DETECT is a protocol; it has no mortality result.

Domain	Status	Use on the ward
Isolated distal DVT, active cancer	ONCO DVT, Circulation 2023. Completed.	12 months of edoxaban beat 3 months for recurrent VTE or VTE death.
Iliofemoral DVT, lytic-free extraction	CLOUT registry, 2023. Single arm.	Technical and 6-month symptom data. Not proof against anticoagulation.
Same question, randomised	DEFIANCE, NCT05701917. Recruiting.	Do not quote a result. Design only.
Chronic PTS, iliac obstruction	C-TRACT, NEJM 13 April 2026.	Endovascular therapy reduced VCSS and improved quality of life at 6 months. Bleeding 11.6% versus 3.6%.
ICU ultrasound surveillance	DETECT protocol, BMJ Open 2025.	Hypothesis. Twice-weekly ultrasound versus usual care. Primary outcome is 90-day mortality. Not yet reported.

Part 2. Diagnosis

Compression ultrasound remains the diagnostic test.

A high-sensitivity D-dimer is a rule-out tool in a low pretest probability, not a severity score.

Shear-wave elastography is investigational and does not choose treatment.

Routine bilateral surveillance ultrasound in the ICU is the question DETECT is asking; it is not yet a standard.

Finding	Decision
Low Wells score, D-dimer below the age-adjusted cut-off	Stop. Do not ultrasound.
Likely pretest probability, or a positive D-dimer	Whole-leg or proximal compression ultrasound.
Iliac symptoms, a normal femoral ultrasound	Image the iliac vein. Compression ultrasound misses the pelvis.
ICU patient, no leg symptoms	Do not start twice-weekly surveillance outside a trial.

Part 3. Proximal iliofemoral DVT

Anticoagulation remains the default. ATTRACT did not show that catheter-directed thrombolysis prevents post-thrombotic syndrome overall, and it increased major bleeding. The open question is whether single-session mechanical thrombectomy, without a lytic, is different. CLOUT, 500 patients, ClotTriever, no control arm: flow present rose from 27.2% to 92.5% of limbs at 6 months, median Villalta from 9 to 1, one device-related severe adverse event (0.2%). A single-centre series in 2025 reported technical success 98.9% and a Villalta fall from 10.5 to 1. That is feasibility. DEFIANCE randomises ClotTriever plus anticoagulation against anticoagulation alone in symptomatic unilateral iliofemoral DVT, symptom onset within 12 weeks, win-ratio primary endpoint, estimated primary completion January 2028.

Scenario	Decision
Femoropopliteal DVT, no phlegmasia, no iliac occlusion	Anticoagulate. Do not offer thrombectomy as standard.
Iliofemoral DVT, limb-threatening phlegmasia	Escalate. Thrombus removal is indicated for the limb, not for a Villalta hypothesis.
Symptomatic iliofemoral DVT, young patient, low bleeding risk, symptomatic within 12 weeks	Discuss a trial or a selected mechanical-thrombectomy pathway. Do not tell the patient DEFIANCE has already won.
Request for catheter-directed thrombolysis as first line	Not the contemporary default. Bleeding and ICU stay are the cost ATTRACT already priced.

Part 4. Cancer-associated isolated distal DVT

ONCO DVT randomised 601 patients with cancer and isolated distal DVT to 12 months or 3 months of edoxaban. Symptomatic recurrent VTE or VTE-related death was 1.0% versus 7.2% (odds ratio 0.13, 95% CI 0.03–0.44). Major bleeding was 9.5% versus 7.2% (odds ratio 1.34, 95% CI 0.75–2.41), not a significant increase. A dose analysis later suggested the thrombotic gain held at 30 mg and at 60 mg, with a bleeding signal at the 60 mg dose. A 2024 net-clinical-benefit letter did not show a significant benefit once bleeding was weighted equally. The trial result stands. The bleeding conversation stands with it.

Scenario	Decision
Active cancer, isolated distal DVT, acceptable bleeding risk	Prefer 12 months of edoxaban over 3 months.
Same patient, standard 60 mg dose, high bleeding risk	Use the labelled reduced dose. Do not extend 60 mg without a bleeding review.
Distal DVT, no cancer, first event, transient risk gone	Serial ultrasound or a short course remains acceptable. ONCO DVT does not transfer.
Cancer, proximal DVT	This is not ONCO DVT. Treat as cancer-associated VTE for at least 6 months, and while cancer is active.

Part 5. Chronic occlusion and post-thrombotic syndrome

C-TRACT, NEJM 13 April 2026, randomised 225 patients with moderate or severe PTS and iliac-vein obstruction to endovascular therapy plus standard care, or standard care. At 6 months, mean VCSS was 8.1 versus 10.0 (adjusted difference −2.0, P=0.001). VEINES-QOL improved by 14.5 points and the SF-36 physical score by 6.1 points. Bleeding was 11.6% versus 3.6% (P=0.03), mostly non-major. Recurrent VTE and death were similar. This is a severity and quality-of-life result at 6 months, not a licence to stent every swollen leg.

Scenario	Decision
Mild PTS, patent iliac vein	Compression, exercise, anticoagulation as indicated. No stent.
Moderate or severe PTS, imaging-proven iliac obstruction	Endovascular reconstruction is now evidence-based. Quote the bleeding cost.
Venous ulcer, iliac occlusion, suitable anatomy	Refer to a venous centre. C-TRACT included wound care in both arms.
May–Thurner anatomy, no thrombus, no severe symptoms	Do not stent an anatomy.

Part 6. Sources

Yamashita Y, et al. Edoxaban for 12 months versus 3 months in patients with cancer with isolated distal deep vein thrombosis (ONCO DVT). Circulation. 2023;148:1665–1676.

Dexter D, et al. Six-month outcomes of mechanical thrombectomy for deep vein thrombosis: CLOUT registry. Cardiovasc Intervent Radiol. 2023;46:1571–1580.

Abramowitz SD, et al. Rationale and design of DEFIANCE. Am Heart J. 2025;281:92–102. NCT05701917, recruiting; estimated primary completion 31 January 2028.

Vedantham S, et al. Endovascular therapy for post-thrombotic syndrome. N Engl J Med. 2026;394:2293–2304. Published online 13 April 2026.

Al-Dorzi HM, et al. DETECT trial protocol. BMJ Open. 2025;15:e104468. No outcome report.

meritmedscript.blogspot.com  ·  Clinical exam notes  ·  October 2026