The Prevalence of Deep Venous Thrombosis in Patients with Suspected Paradoxical Embolism

To determine the prevalence of venous thrombosis in patients with suspected paradoxical embolism.

Observational study.

Two hundred sixty-four patients with clinically suspected embolic events underwent contrast transesophageal echocardiographic evaluation. Forty-nine patients (24 women, 25 men) had a patent foramen ovale. Forty-one patients had acute stroke, and 8 had acute limb ischemia.

Echocardiography laboratory of a community hospital.

The presence of a patent foramen ovale was assessed by transesophageal contrast echocardiography. Forty-two patients had venographic evaluation of the lower-extremity venous system.

Venous thrombosis was clinically suspected in 6 patients and documented in 24 of the 42 patients with patent foramen ovale who underwent venographic study (57%; 95% CI, 41% to 72%). Venous thrombosis was confined to calf or popliteal veins in 15 cases. Fifteen of 17 patients who had venographic evaluation within 7 days of the index event had thrombosis compared with 9 of 25 patients who had later evaluations (P = 0.001). More patients with venous thrombosis than without venous thrombosis had a history of previous thromboembolism (13 of 24 compared with 1 of 8, respectively; P = 0.001).

When a patent foramen ovale is detected in a patient with embolism, occult leg vein thrombosis is frequently present.