Resolution of pulmonary embolism on CT pulmonary angiography.

OBJECTIVE: The objective of our study was to retrospectively determine the rate of resolution of pulmonary emboli (PEs) in individual vessels and the rate of complete resolution of PEs on CT angiography. MATERIALS AND METHODS: Follow-up CT pulmonary angiograms, obtained during the period from January 2006 through May 2009, of 69 patients with acute PE from two hospitals were assessed. Initial and follow-up CT angiograms were reread together by one radiologist at both of the hospitals. Images were obtained using a 10-, 16-, 40-, or 64-MDCT angiography unit with a 0.5-mm collimation, 1.25- to 2.0-mm reconstruction, 0.3- to 0.5-second rotation time, and 7.5-mm/rotation table speed. All CT angiograms were obtained using a PE protocol. RESULTS: Follow-up CT angiograms were obtained in 35 men and 34 women who ranged in age from 17 to 92 years (mean age, 58 +/- 17 [SD] years). Complete CT angiographic resolution of PE was seen in six of 15 patients (40%) 2-7 days after diagnostic imaging. After day 28, complete resolution occurred in 17 of 21 patients (81%). The main pulmonary arteries showed complete PE resolution during days 2-7 in seven of nine patients (78%) and after day 28 in 34 of 36 (94%). The lobar pulmonary arteries showed complete resolution of PE during days 2-7 in 23 of 33 patients (70%) and after 28 days in 44 of 48 (92%). The segmental pulmonary arteries showed complete resolution during days 2-7 in eight of 21 patients (38%) and after day 28 in 38 of 38 (100%). CONCLUSION: Most patients (81%) showed complete resolution of PE on CT angiography after 28 days. PEs resolved faster in the main and lobar pulmonary arteries than in the segmental branches.

Risk of venous thromboembolism with rheumatoid arthritis.

Rheumatoid arthritis is not generally considered to be a risk factor for venous thromboembolism (VTE), although abnormalities of coagulation factors have been found in patients with rheumatoid arthritis. Sparse data in a few patients suggest that patients with rheumatoid arthritis may have higher rates of VTE. The purpose of this investigation was to determine if the incidences of pulmonary embolism (PE) and deep venous thrombosis (DVT) are increased in hospitalized patients with rheumatoid arthritis. The number of patients discharged from non-Federal short-stay hospitals throughout the United States from 1979 through 2005 with a discharge code for rheumatoid arthritis was obtained from the National Hospital Discharge Survey (NHDS). Among hospitalized patients with rheumatoid arthritis who did not have joint surgery, 41,000 of 4,818,000 (0.85%) had PE compared with 3,366,000 of 891,055,000 (0.38%) among patients who did not have rheumatoid arthritis and who did not have operations or joint surgery (relative risk = 2.25). Deep venous thrombosis was diagnosed in 79,000 of 4,818,000 (1.64%) patients with rheumatoid arthritis and no joint operation, versus 7,681,000 of 891,055,000 (0.86%) who did not have rheumatoid arthritis or a joint operation (relative risk = 1.90). The relative risk of venous thromboembolism (PE and/or DVT) in these patients was 1.99. The data suggest that rheumatoid arthritis is a risk factor for VTE in hospitalized medical patients. A heightened awareness of the risks for VTE and a lower threshold for evaluation of patients for possible DVT or PE would be appropriate in caring for hospitalized patients with rheumatoid arthritis.

Ankle exercise and venous blood velocity.

Ankle exercise increases venous blood velocity while supine, but the effect of ankle exercise on venous blood velocity while sitting is not known. In this investigation, we test the hypothesis that venous blood velocity can be increased while sitting by repetitive dorsiflexion of the foot. Time-averaged peak velocity (TAPV) in the popliteal vein of 20 healthy male volunteers was measured by pulsed Doppler ultrasound at rest and during ankle exercise in the supine and sitting positions. Right popliteal vein TAPV while supine at rest was 11 cm/second (sec) (95% confidence interval [CI] =9-13 cm/sec) and with ankle exercise it increased to 24 cm/sec (95% CI =20-28 cm/sec) (p<0.0001). With sitting at rest, right popliteal vein blood TAPV decreased from 11 cm/sec to 3 cm/sec (95% CI = 2-4 cm/sec) (p<0.0001). With ankle exercise while sitting, right popliteal vein TAPV increased to 18 cm/sec (95% CI =15-21 cm/sec) (p<0.0001). In conclusion, in both the supine and sitting positions, ankle exercise increased venous blood velocity, thereby transiently reducing a tendency toward venous stasis. Such ankle exercise might be useful in the prevention of stasis-induced deep venous thrombosis.

Reconstructed 4-chamber views compared with axial imaging for assessment of right ventricular enlargement on CT pulmonary angiograms.

PURPOSE: To test the hypothesis that right enlargement assessed from right ventricular/left ventricular (RV/LV) dimension ratios of computed tomographic (CT) angiograms are equivalent irrespective of whether measured on axial views or reconstructed 4-chamber views. METHODS: RV/LV dimension ratios were calculated from measurements on axial views, manually reconstructed 4-chamber views and computer generated reconstructed 4-chamber views of CT angiograms in 152 patients with PE. RESULTS: Paired readings of the axial view and manually reconstructed 4-chamber view showed agreement with RV/LV > or =1 or RV/LV <1 in 114 of 127 (89.8%). Paired readings also showed agreement in 119 of 127 (93.7%) with axial views and computer generated reconstructed 4-chamber views. The McNemar test showed no statistically significant difference between assessments of RV enlargement (RV/LV > or = 1) with any method. CONCLUSION: Right ventricular enlargement can be determined from axial views on CT angiograms, which are readily and immediately available, without obtaining 4-chamber reconstructed views.

Diabetes mellitus and risk of venous thromboembolism.

BACKGROUND: : To determine if diabetes mellitus is a risk factor for venous thromboembolism (VTE). RESEARCH DESIGN AND METHODS: : Data from the National Hospital Discharge Survey were analyzed from 1979 to 2005. International Classification of Diseases, Ninth Revision, Clinical Modification codes were used to identify diseases. RESULTS: : Among 92,240,000 patients with diabetes mellitus discharged between 1979 and 2005, 1,267,000 (1.4%) had VTE. The relative risk for VTE was elevated only in patients younger than 50 to 59 years and was highest in patients aged 20 to 29 years (relative risk = 1.73). Relative risks of VTE with uncomplicated type 1 diabetes mellitus and uncomplicated type 2 diabetes mellitus were similar and also age dependent. In patients with uncomplicated diabetes mellitus who did not have obesity, stroke, heart failure, or cancer, compared with those who did not have diabetes mellitus and did not have any of these comorbid conditions, the relative risk for VTE was 1.52 in patients aged 20 to 29 years and 1.19 in patients aged 30 to 39 years. In older patients, the relative risk of VTE in patients with diabetes mellitus was not increased. CONCLUSIONS: : Diabetes mellitus carries an increased risk for VTE, which is apparent only in younger patients in whom comorbid conditions that also increase the risk of VTE are unlikely to be present.

Treatment of acute pulmonary embolism as outpatients or following early discharge. A systematic review.

The purpose of this systematic review is to test the hypothesis that carefully selected low-risk patients with acute pulmonary embolism (PE) can safely be treated entirely as outpatients or after early hospital discharge. Included articles were required to describe inclusion or exclusion criteria and outcome of patients treated for PE. Early hospital discharge was defined as an average hospital stay < or = 3 days. Six investigations included patients with PE who were treated entirely as outpatients; two investigations included patients with PE who were treated after early discharge. All investigations included only low-risk patients or patients with small or medium sized PE. Outcome after 3-46 months in patients treated entirely as outpatients showed recurrent PE in 0% to 6.2% of patients, major bleeding in 0% to 2.8% with one death from an intracerebral bleed. Definite death from PE did not occur, but there was one possible death from PE. Outcome in three months in patients treated after early discharge showed no instances of recurrent PE. Major bleeding occurred in 0% to 3.7% of patients. There were no deaths from PE, but there was one death from bleeding. In conclusion, outpatient therapy of acute PE is probably safe in low-risk, carefully selected compliant patients who have access to outpatient care if necessary. Such outpatient treatment would be cost-effective.

Incidence of vena cava thrombosis in the United States.

From 1979 through 2005, vena cava thrombosis (either superior or inferior) was diagnosed in 99,000 hospitalized patients. Most, 78%, had isolated vena cava thrombosis. From 2000 to 2005, 5,000 patients were diagnosed yearly with vena cava thrombosis (1.5% of patients hospitalized with deep venous thrombosis). The population-based incidence of diagnosis of vena cava thrombosis from 2001 to 2005 was 1.7 in 100,000. The incidence increased with age. It was rare in Asian Americans. Pulmonary embolism occurred in 12% of patients with isolated vena cava thrombosis. Cancer was frequently associated with vena cava thrombosis (37.5%). Among all patients hospitalized with cancer, however, it was an uncommon complication (0.07%). In conclusion, isolated vena cava thrombosis is an uncommon cause of pulmonary embolism but may be considered if the veins of the extremities show no deep venous thrombosis.

Human immunodeficiency virus infection and risk of venous thromboembolism.

BACKGROUND: The incidence of venous thromboembolism (VTE) in HIV-infected patients is uncertain, and the impact of protease inhibitors on the incidence of VTE is also uncertain, yet important to know to create a database for providing opinion regarding prophylaxis for the prevention of VTE. METHODS: Data from the National Hospital Discharge Survey (NHDS) were analyzed from 1990 through 2005. International Classification of Diseases, Ninth Revision, and Clinical Modification (ICD-9-CM) codes were used to identify illnesses. RESULTS: Among 2,429,000 patients older than 18 years hospitalized with HIV infection, the incidence of pulmonary embolism (PE) was 0.4%, deep venous thrombosis (DVT) 1.4%, and VTE 1.7%. The relative risks compared with all hospitalized non-HIV patients of PE, DVT, and VTE were 0.91, 1.26, and 1.21. The incidence of VTE from 1990 to 1996 was 17,000 of 1,198,000 (1.4%) and after 1996 it was 25,000 of 1,230,000 (2.0) (P < 0.0001) (relative risk = 1.43). Among hospitalized patients who did not have HIV, the relative risk comparing incidences after 1996 with incidences before was 1.22. CONCLUSION: The incidence of VTE in patients with HIV infection was higher than in non-HIV patients. The incidence of VTE in patients with HIV in the postprotease inhibitor era (after 1996) was higher than in HIV patients before 1996, but the incidence was also higher in non-HIV patients after 1996. The higher incidence since 1996 is small, probably not clinically significant, and not necessarily because of protease inhibitors.

Fat embolism syndrome.

OBJECTIVES: To assess the incidence and risk factors for fat embolism syndrome. MATERIALS AND METHODS: Data from the National Hospital Discharge Survey (NHDS) were analyzed using International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) codes. RESULTS: From 1979 through 2005 among 928,324,000 patients discharged from short-stay hospitals in the United States, 41,000 (0.004%) had fat embolism syndrome. Among 21,538,000 patients with an isolated fracture of the femur (any site), tibia, fibula, pelvis, ribs, humerus, radius, or ulna, 25,000 (0.12%) developed fat embolism syndrome. Patients with multiple fractures of the femur (excluding neck) more often had fat embolism syndrome than those with isolated fractures (1.29% versus 0.54%). The incidence of fat embolism syndrome was lower with isolated fractures of the tibia or fibula (0.30%) and even lower with isolated fractures of the neck of the femur (0.06%). The incidence of fat embolism was too low to calculate with isolated fractures of the pelvis, ribs, humerus, radius, or ulna. Nonorthopedic conditions rarely, if ever, were accompanied by fat embolism syndrome. The fat embolism syndrome was more frequent in men (relative risk 5.71). Children, aged 0 to 9 years rarely had fat embolism syndrome. The fat embolism syndrome most commonly affected patients aged 10 to 39 years. CONCLUSIONS: The incidence of the fat embolism syndrome depends on the bone involved, whether fractures are isolated or multiple, the age of the patient and the gender. It rarely occurs as a result of medical conditions.

Risk of venous thromboembolism with inflammatory bowel disease.

The purpose of this study is to determine the incidence of venous thromboembolism (VTE) in patients with ulcerative colitis and patients with Crohn disease. The number of patients discharged from hospitals throughout the United States with a diagnostic code for ulcerative colitis and for Crohn disease from 1979 through 2005 was obtained from the National Hospital Discharge Survey. The incidence of VTE among medical patients with ulcerative colitis was 21 000 of 1 129 000 (1.85%) and among medical patients who had no inflammatory bowel disease, the incidence was 10 421 000 of 918 570 000 (1.13%; relative risk 1.64, 95% confidence interval [CI] = 1.62-1.66). The incidence of VTE among medical patients with Crohn disease was less than those with ulcerative colitis, 22 000 of 1 803 000 (1.22%). The risk, compared with patients who did not have inflammatory bowel disease, was only marginally increased (relative risk 1.08, 95% CI = 1.06-1.09).

Elevated cardiac biomarkers with normal right ventricular size indicate an unlikely diagnosis of acute pulmonary embolism in stable patients.

The purpose of this investigation is to assess the prevalence of elevated cardiac biomarkers, with or without estimates of right ventricular (RV) size, in stable patients with acute pulmonary embolism (PE). Our hypothesis is that the combination of high levels of cardiac troponin I (cTnI), high creatine kinase isoenzyme MB (CK-MB), and normal size RV are sufficiently uncommon in stable patients with PE to make the diagnosis of PE unlikely. Retrospective review showed a high cTnI plus high CK-MB in 20 (3.4%) of 585 stable patients with acute PE. A high cTnI plus high CK-MB with normal RV size was shown in 5 (1.9%) of 264 patients. In stable patients with such findings, therefore, PE is unlikely and other diagnoses, particularly acute coronary syndrome, should be considered before pursuing a diagnosis of PE.

Early discharge of patients with venous thromboembolism: implications regarding therapy.

The purpose of this investigation is to show trends in the duration of hospitalization of patients with pulmonary embolism (PE) and deep venous thrombosis (DVT). The number of patients discharged from short-stay non-Federal hospitals throughout the United States with a primary diagnostic code for PE or DVT from 1979 through 2005 was obtained from the National Hospital Discharge Survey. By 2005, 13% of patients with PE were discharged in 1 to 2 days, 30% in 3 to 4 days, 26% in 5 to 6 days, and 31% in > or =7 days. Regarding DVT, by 2005, 26% of patients with DVT were discharged in 1 to 2 days, 34% were discharged in 3 to 4 days, 20% were discharged in 5 to 6 days, and 19% were discharged in > or =7 days. The data indicate that large proportions of patients with a primary diagnosis of PE and of DVT are being discharged before adequate heparin can be administered and before warfarin can become antithrombotic. Others have reported an increased mortality among patients with PE discharged in < or =4 days. If patients are to be discharged before adequate heparin can be administered, outpatient treatment with low-molecular-weight heparin (LMWH) for at least 5 days and until the international normalized ratio (INR) is > or =2.0 for 24 hours is recommended or extended outpatient treatment with LMWH may be considered.

Venous compression for prevention of postthrombotic syndrome: a meta-analysis.

PURPOSE: To determine the effectiveness of venous compression stockings or compression bandages on the reduction of postthrombotic syndrome in patients with deep venous thrombosis. METHODS: We attempted to identify all published trials in all languages identified by PubMed through June 2009. Meta-analysis was performed. RESULTS: Based on 5 randomized trials of patients with deep venous thrombosis comparing treatment with venous compression to controls, mild-to-moderate postthrombotic syndrome occurred in 64 of 296 (22%) treated with venous compression, compared with 106 of 284 (37%) in controls (relative risk=0.52). Severe postthrombotic syndrome occurred in 14 of 296 (5%) treated, compared with 33 of 284 (12%) controls (relative risk=0.38). Any postthrombotic syndrome occurred in 89 of 338 (26%) treated, compared with 150 of 324 (46%) controls (relative risk=0.54). CONCLUSION: Venous compression reduced the incidence of postthrombotic syndrome, particularly severe postthrombotic syndrome. Venous compression in patients with deep venous thrombosis would seem to be indicated for this purpose. There was, however, wide variation in the type of stockings used, time interval from diagnosis to application of stockings, and duration of treatment. Further investigation, therefore, is needed.

Outcome in stable patients with acute pulmonary embolism who had right ventricular enlargement and/or elevated levels of troponin I.

Normotensive patients with acute pulmonary embolism (PE) who have increased troponin levels and right ventricular (RV) dysfunction are thought to be at high risk of death, but the level of risk is unclear. We retrospectively evaluated outcome in 1,273 stable patients with PE who had echocardiographic evaluations of RV size and/or measurement of cardiac troponin I (cTnI). In-hospital all-cause mortality was higher in those with RV enlargement (8.0%, 19 of 237, vs 3.3%, 22 of 663, p = 0.003). With an increased cTnI, irrespective of RV enlargement, all-cause mortality was 8.0% (28 of 330) versus 1.9% (15 of 835) in patients with a normal cTnI (p <0.0001). In patients with an increased cTnI combined with an enlarged right ventricle, all-cause mortality was 10.2% (12 of 118) compared to 1.9% (8 of 421) in patients who had neither (p <0.0001). These data show that increased levels of cTnI and RV enlargement are associated with an adverse outcome in stable patients with acute PE. In conclusion, increased levels of cTnI in combination with RV enlargement might indicate a group who would benefit from intense monitoring and aggressive treatment if subsequently indicated. The outcomes, however, were not extreme enough to warrant routine thrombolytic therapy.

Outcomes with retrievable inferior vena cava filters.

This was a retrospective study of 144 patients with retrievable inferior vena cava (IVC) filters inserted between 2004 and 2008 at a community/teaching hospital. The purpose was to evaluate the incidence of complications and the rate and success of retrieval. Retrieval of IVC filters was attempted in 14 of 144 (10%) patients at an average of 4.6 months. Retrieval was successful in 10 of 14 (71%). Within 6 months of insertion, retrieval was successful in 10 of 12 (83%). Unsuccessful attempts were at 3, 6, 8 and 9 months. Non-bleeding complications of IVC filters occurred in 12 of 144 (8.3%). Half (6 of 12) of the complications occurred after 3 months of insertion. Complications included IVC thrombosis in 3 (2.1%) (1 also had a new deep venous thrombosis [DVT]), a new DVT alone in 6 patients (4.2%), a new DVT with new pulmonary embolism (PE) in 1 patient (0.7%) and filter migration in 2 patients (1.3%). In conclusion, retrieval was attempted in only a small proportion of patients at a community/teaching hospital. Formalized guidelines for follow up may increase the proportion of patients in whom retrieval is attempted. Half of the complications of IVC filters could have been avoided with retrieval within 3 months.

CT venous phase venography with 64-detector CT angiography in the diagnosis of acute pulmonary embolism.

The value of computed tomographic (CT) venography in combination with CT pulmonary angiography has been questioned because of the potential dangers of radiation. Accordingly, we retrospectively evaluated the diagnostic yield of 64-detector CT angiography with CT venography. Among patients who routinely underwent CT venography with CT angiography, the CT angiogram showed acute pulmonary embolism (PE) in 206 of 1903 patients (10.8%). A positive CT venogram in a patient with a negative CT angiogram was shown in 25 of 1903 patients (1.3%). Either the CT angiogram or the CT venogram showed venous thromboembolism in 231 of 1903 patients (12.1%). The proportion of patients with venous thromboembolism diagnosed only by a CT venogram was 25 of 231 (10.8%). In conclusion, the proportion of patients with venous thromboembolism diagnosed only by a CT venogram is sufficiently high to merit consideration of its use especially in those at high risk for DVT.

Incidence of amniotic fluid embolism: relation to cesarean section and to age.

AIMS: To determine the incidence of amniotic fluid embolism and the incidence as modified by cesarean section and age. METHODS: Data are from the National Hospital Discharge Survey. We examined the number of patients discharged from short-stay nonfederal hospitals throughout the United States, from 1980 through 2005, with a diagnostic code for amniotic fluid embolism. RESULTS: From 1980 through 2005, there were 112,712,000 deliveries, of which 12,000 patients (11/100,000) had amniotic fluid embolism. The incidence of amniotic fluid embolism was lower in 1993-2005 than in 1980-1992 (9/100,000 vs. 12/100,000)(p < 0.0001). The incidence of amniotic fluid embolism was higher with cesarean section, 5,000 of 22,937,000 (22/100,000) than with vaginal delivery, 7,000 of 89,775,000 (8/100,000) (relative risk 2.80, 95% CI 2.70-2.90) (p < 0.0001). The incidence was also higher in women aged 30-39 years, 6,000 of 35,039,000 (17/100,000) than in women aged 15-29 years, 6,000 of 77,673,000 (8/100,000) (relative risk 2.22, 95% CI 2.14-2.30) (p < 0.0001). CONCLUSIONS: The incidence of amniotic fluid embolism has decreased since the early 1990s. The risk is higher with cesarean section and higher in women aged > or =30 years.

Anticoagulant therapy for acute venous thromboembolism: what we think we know and what the data show for the timing of recurrent events.

Although heparin is administered to prevent early recurrences of venous thromboembolism (VTE) by preventing new thrombi, allowing old thrombi to attach to venous walls, and covering warfarin until it is therapeutic, heparin largely prevents late recurrences of VTE (after 5 days). The dreaded early occurrence of pulmonary embolism (PE) (on or before day 5) while waiting for the vitamin K antagonist to become antithrombotic did not occur among patients with deep venous thrombosis (DVT), who received acencoumarol alone. Fewer total recurrences resulted if a therapeutic level of heparin was reached within the first 24 hours of treatment of DVT. Fewer total recurrences also resulted if heparin was consistently maintained at therapeutic levels. A recurrent VTE within 5 days, however, occurred infrequently in those in whom heparin was not given, or therapeutic levels were delayed or not maintained. The incidence of early recurrent VTE was not lower in those who received adequate heparin than in those who did not, although the data are sparse. The true incidence of early recurrent VTE is uncertain due to the broad confidence intervals for the observed frequency of early recurrent events. Later recurrences are the norm and may be reduced by early treatment with adequate heparin.

Incidence of thrombocytopenia in hospitalized patients with venous thromboembolism.

PURPOSE: To determine the incidence of heparin-associated thrombocytopenia in patients receiving prophylaxis or treatment for venous thromboembolism. METHODS: We assessed the database of the National Hospital Discharge Survey from 1979 through 2005 and complemented this with a meta-analysis of published literature. RESULT: Among 10,554,000 patients discharged from short-stay hospitals throughout the US with venous thromboembolism during the 27 years of study, secondary thrombocytopenia was coded in 38,000 patients (0.36%). From 1979 through 1992, secondary thrombocytopenia was coded in only 0.15% of hospitalized patients with venous thromboembolism. The frequency increased sharply to 0.54% from 1993 through 2005. Secondary thrombocytopenia was rarely diagnosed among 1,446,000 patients aged <40 years and among 77,000 women who had venous thromboembolism with deliveries. Meta-analysis of published literature showed a higher incidence among patients who received unfractionated heparin (UFH) for prophylaxis than those who received low-molecular-weight heparin (LMWH) for prophylaxis. Treatment resulted in smaller differences of the incidence between UFH and LMWH. CONCLUSION: Heparin-associated thrombocytopenia is rare among patients aged <40 years and women following delivery. The risk of heparin-associated thrombocytopenia is more duration-related than dose-related, and higher with UFH when used for an extended duration. Our findings and those of the literature suggest that although heparin-associated thrombocytopenia is uncommon, the incidence can be minimized by use of LMWH, particularly if extended prophylaxis or extended treatment is required.

Venous thromboembolism in patients hospitalized with thyroid dysfunction.

The objective of this investigation is to explore a possible role of thyroid dysfunction in venous thromboembolism (VTE). The number of patients discharged from short-stay nonfederal hospitals in the United States, from 1979 to 2005, with a diagnostic code for hypothyroidism or hyperthyroidism, pulmonary embolism (PE), and deep venous thrombosis (DVT) was obtained from the National Hospital Discharge Survey (NHDS). Among 19,519,000 hospitalized patients discharged with a diagnosis of hypothyroidism from 1979 to 2005, 119,000 (0.61%) had PE. Among patients with no thyroid dysfunction, PE was diagnosed in 3,372,000 of 908,805,000 patients (0.37%; relative risk = 1.64, 95% CI 1.63-1.65). Deep venous thrombosis was diagnosed in 1.36% of hypothyroid patients and in 0.84% of patients with no thyroid dysfunction (relative risk = 1.62, 95% CI 1.61-1.62). The relative risk of PE in patients with hypothyroidism was highest in patients <40 years of age (relative risk = 3.99) and the relative risk of DVT was also highest in patients <40 years (relative risk = 2.25). Hyperthyroidism was not associated with an increased risk of VTE (relative risk = 0.98, 95% CI = 0.96-1.01). In conclusion, an increased risk of PE, DVT, and VTE was shown in patients with hypothyroidism but not hyperthyroidism. Antithrombotic prophylaxis in patients with severe hypothyroidism, however, should be viewed with caution because of a possible hyperfibrinolytic state in such patients.