Proximal DVT associated with worse outcomes than isolated distal deep vein thrombosis: JAMA

USA: Isolated distal deep vein thrombosis (IDDVT) causes lower all-cause mortality and fewer venous thromboembolism (VTE) deterioration events compared to proximal deep vein thrombosis (DVT), states an article published in the JAMA Cardiology.

Deep vein thrombosis, a blood clot in a deep vein, usually in the legs is the third most common vascular disease. Most DVTs resolve on their own, but if the clot breaks loose and travels to the lung [pulmonary embolism (PE)], the prognosis can be more severe. Proximal DVT is thrombosis located in the popliteal, femoral, or iliac veins. Isolated distal DVT (IDDVT) is thrombosis in infrapopliteal veins without proximal extension or PE and accounts for one-fourth to one-half of all diagnosed leg DVTs. Insufficient data exist about the clinical presentation, and short-term, and long-term outcomes of patients with IDDVT.

Bikdeli B, Harvard Medical School, Massachusetts, and the research team conducted a study to determine the clinical characteristics, short-term, and 1-year outcomes in patients with IDDVT and to compare them with patients with proximal DVT

Researchers analyzed data of 33,897 patients with IDDVT and 5,938 patients with proximal DVT using data from the RIETE registry. Patients with a history of asymptomatic DVT, upper-extremity DVT, coexisting PE, or COVID-19 infection were excluded from the study. Primary outcomes were 90-day and 1-year mortality, 1-year major bleeding, and 1-year venous thromboembolism (VTE) deterioration, which was defined as the subsequent development of proximal DVT or PE.

Key findings of the analysis,

• Compared to patients with proximal DVT, those with IDDVT had a lower comorbidity burden but were more likely to have had recent surgery or to have received hormonal therapy

• Patients with IDDVT had a lower risk of 90-day mortality compared to those with proximal DVT (OR- 0.47). Findings were similar in 1-year unadjusted analyses (HR-0.52) and adjusted analyses (HR-0.72)

• Patients with IDDVT had a lower 1-year hazard of VTE deterioration (HR-0.83).

• Additionally, in 1-year adjusted analyses of patients without an adverse event within the first 3 months, IDDVT was associated with a lower risk of VTE deterioration (adjusted HR-0.48)

• By 1-year follow-up, symptoms or signs of the post-thrombotic syndrome were less common in patients with IDDVT (47.6% vs 60.5%).

The authors conclude that patients with IDDVT had a less dire prognosis compared to those with proximal DVT. These differences were likely multifactorial, including demographics, risk factors, comorbidities, particularly for all-cause mortality, and a potential association of thrombus location with VTE deterioration and post-thrombotic syndrome. Mortality related to pulmonary embolism (PE) was low in short- and long-term follow-up of patients with IDDVT.

Future RCTs are needed to assess the optimal long-term management of IDDVT, the authors wrote.

Reference:

Bikdeli B, Caraballo C, Trujillo-Santos J, et al. Clinical Presentation and Short- and Long-term Outcomes in Patients With Isolated Distal Deep Vein Thrombosis vs Proximal Deep Vein Thrombosis in the RIETE Registry. JAMA Cardiol. Published online July 13, 2022. doi:10.1001/jamacardio.2022.1988