What is Thromboembolic Event?
Thromboembolic events, a type of blood clot, are some of the most dangerous risks associated with hospital stays. Venous thromboembolism (VTE), a blood clot that starts in a vein, is the third most common heart-related condition after heart attacks and strokes. The American Heart Association states that it affects 300,000 to 600,000 people per year, leading to significant costs. VTE is an umbrella term that includes deep vein thrombosis (DVT), a blood clot in a deep vein, usually in the leg, and pulmonary embolism (PE), a blockage in one of the pulmonary arteries in your lungs.
When combined with a person’s natural tendency to form blood clots and certain medical conditions that increase this risk, VTE can pose a serious risk of health complications and death for a large portion of the global population. There’s been considerable research aimed at identifying those at risk and providing necessary preventive measures. Despite these efforts, VTE continues to be a growing public health issue, and significant steps need to be taken to increase awareness among the general public and healthcare providers.
What Causes Thromboembolic Event?
The likelihood of a person developing a condition involving blood clots, called thromboembolic disease, depends on many factors. These include individual qualities, existing health conditions, recent or upcoming surgeries, and blood-related disorders. It’s a combination of all these factors that calculates a person’s risk of getting Venous Thromboembolism (VTE), a specific type of blood clot, at any given time.
Personal factors that can contribute to this risk include being over 40, being overweight, having varicose veins (swollen and twisted veins), and not being mobile. Additionally, things like smoking or using birth control pills can also raise the risk.
There are health issues also known for raising the risk of VTE. These include cancer, spinal cord injuries that lead to paralysis, and a condition known as nephrotic syndrome which affects the kidneys. Heart failure, inflammatory bowel disease, and recently having heart attack can all increase risk too.
Bone fractures in the hip, pelvis, or long bones, as well as orthopedic surgeries involving the hip and knee, can also increase the chance someone will get VTE.
There are certain blood disorders that can make your blood more likely to clot (hypercoagulability). These include factor V Leiden mutation (a variant of protein C), deficiencies in certain proteins (C or S), antithrombin III deficiency, presence of lupus anticoagulant (a type of antibody), dysfibrinogenemia (a disorder involving fibrinogen – a protein needed for clotting), prothrombin mutation (a gene mutation), polycythemia vera (a rare bone marrow disorder), and paroxysmal nocturnal hemoglobinuria (a rare, life-threatening blood disease). Pregnancy also increases the risk of getting VTE.
To identify those who are at the highest risk of getting VTE in a hospital setting, and to properly prevent these clots, a number of risk measurement models have been created. These include the Caprini, the Brigham and Women’s Hospital (Kucher), Padua, Roger’s, Intermountain, IMPROVE, and Premier models. The Caprini model was the first to be validated and used around the world. The others have also been checked for accuracy and put into use.
Risk Factors and Frequency for Thromboembolic Event
Every year, there are millions of venous thromboembolism (a condition where blood clots form in the veins) cases globally. This condition contributes to a high number of illnesses and deaths. In the United States alone, between 100,000 and 300,000 deaths are reported each year due to this issue. Europe has an even higher number, with over 500,000 annual deaths. Most of these cases, about 60% of them, occur in hospitals, which makes venous thromboembolism the top cause of preventable death for hospitalized patients.
Signs and Symptoms of Thromboembolic Event
Deep Vein Thrombosis (DVT) often presents with one-sided limb pain, which might include swelling, warmth, and sensitivity. But, diagnosing DVT based solely on these physical signs isn’t effective.
On the other hand, Pulmonary Embolism (PE) typically starts with sudden difficulty breathing. Additional symptoms can include chest pain, coughing, and in some situations, coughing up blood. Serious instances of PE might cause fainting, low blood pressure, and shock. Physical signs may include low oxygen levels, rapid heartbeat, fever, and quick, shallow breaths. Feelings of discomfort in the chest might be an indicator of PE in patients with sickle cell disease. For older people, newly developed irregular heartbeat can suggest PE. However, physical exam findings for PE can vary and might not give a definitive diagnosis.
For patients with an established PE, quick, shallow breaths are the most common physical symptom. Additional signs may include abnormal hear sounds, rapid heart rate, and fever. Some patients might sweat excessively and have abnormal heart sounds, while others will have a particular type of chest pain. Patients who experience recurrent VTE syndromes could show signs of high blood pressure in the lungs and right-sided heart failure, with difficulty breathing being the most common symptom. On physical examination, the doctor might be able to feel a strong pulse over a specific area in the chest, hear abnormal heart sounds, or notice a certain heart murmur. Some might also have an enlarged liver and swollen lower limbs.
The Modified Well’s criteria is a scoring tool doctors use to gauge the likelihood of VTE in patients, assigning points based on certain factors. Those with less than 2 points are considered low risk, those with 2 to 6 points are moderate risk, and those with over 6 points are at high risk. Another scoring system simplifies these categories, considering those with 4 points or more as likely to have PE.
However, given the variable and unreliable nature of these signs and symptoms for diagnosing DVT and PE, patients suspected to have VTE with low scores are usually assessed using a sensitive D-dimer assay test. On the other hand, those with high scores are typically further evaluated using more definitive tests.
Testing for Thromboembolic Event
When a doctor suspects a patient might have a venous thromboembolism (VTE), a condition where blood clots form in the vein, they can use various tests to confirm or rule out this disease. If a patient is considered at low risk, they might undergo a D-Dimer assay – a blood test that can help detect if a blood clot might be present. A negative result could mean the likelihood of a VTE is low. However, this test isn’t perfect – it isn’t highly sensitive and can’t definitively diagnose a VTE.
If VTE is suspected in the lungs – a condition known as pulmonary embolism or PE – doctors used to rely on a procedure called pulmonary angiography. However, because this is invasive, it isn’t used as often nowadays. Instead, if the D-Dimer test shows potential issues, then doctors will usually use imaging techniques like Ventilation-Perfusion Scan (V/Q Scan) or Computed Tomography Pulmonary Angiography (CTPA) to check for PE.
When a doctor believes that their patient might have deep vein thrombosis (DVT), a type of VTE that occurs in the deep veins of the body, they often use ultrasonography. This kind of medical imaging allows them to get a detailed view of the patient’s blood vessels and see if any blood clots are present. Repeat scans might be necessary if the original does not show a clot, but suspicion remains high.
There are factors to be aware of with these tests. The D-dimer assay can show positive results in conditions like pneumonia, cancer, sepsis, and even after recent surgery. It is also sensitive to a patient’s age and kidney function. The American College of Radiology suggests using CTPA to find PE because it provides extra helpful information.
The PERC rule was made to minimize unnecessary testing in patients at low risk for PE. This rule states that patients under 50, with a pulse under 100, with oxygen levels over 94%, no leg swelling or recent trauma or surgery, and who don’t use estrogen, are low risk for PE. Positive D-dimer results then are likely false positives.
Other diagnostic steps – such as arterial blood gas, troponin level, brain natriuretic peptide, and tests like chest X-rays or electrocardiogram – are not usually beneficial for most people. However, in some cases, they can provide extra insight into patients’ conditions and help rule out other potential issues. For example, an Echocardiography can be helpful in cases where there is suspicion of a large PE, as it is can confirm right ventricular dysfunction and that in turn aids in confirming acute submassive or massive pulmonary embolism. However, it is not a standard part of the assessment for PE.
Overall, diagnosing VTEs is about considering multiple pieces of information. The actual test used will be based on the individual patient’s symptoms, risk factors, and overall health status.
Treatment Options for Thromboembolic Event
Anticoagulants, or blood thinners, are the primary treatment option for venous thromboembolism (VTE), a condition that includes deep vein thrombosis (DVT) and pulmonary embolism (PE). Therapies like clot-dissolving drugs and filters placed in veins are reserved for complex cases. Blood thinners that are taken orally, such as apixaban, dabigatran, edoxaban, and rivaroxaban, are generally preferred over heparin injections and vitamin K antagonists (another type of blood thinner). It’s crucial to remember that vitamin K antagonists don’t work effectively without the assistance of heparin treatment for at least five to seven days.
The common practice is to continue anticoagulant treatment for three to six months during your first episode of VTE. However, if you’re experiencing a DVT that hasn’t travelled far and you are at low risk of it happening again, it’s safe to have a shorter course of anticoagulation lasting between four to six weeks, as recommended by The European Society of Cardiology.
People without cancer should be treated with direct oral anticoagulants or warfarin. For patients with obesity, the American Society of Hematology recommends using their actual weight rather than a modified dose to administer the drug used to treat VTE, called low-molecular-weight heparin. For those with cancer, low-molecular-weight heparin is the preferred medication to treat acute VTE.
If you are pregnant, the preferred initial and long-term treatment will also be with low molecular-weight heparin. It’s important to know that treatment should typically continue for at least six weeks after childbirth, and for a minimum total duration of three months.
Vena cava filters, which are placed in a large vein to prevent blood clots from reaching the heart or lungs, should only be considered if you cannot take anticoagulant medications. Since these filters are not as effective as anticoagulant treatment in preventing VTE, it’s recommended they are continually evaluated for their suitability.
Clot-dissolving (thrombolytic) therapy is recommended in severe cases of PE that has caused instability in blood circulation. However, it’s crucial to consider the factors that may make this kind of treatment dangerous for some patients. Thrombolytic therapy might also be considered for DVT cases where the blood flow is entirely blocked, posing a risk of compartment syndrome, a painful condition caused by pressure buildup from internal bleeding or swelling of tissues.
After a second case of VTE, the common course of action is lifelong anticoagulation treatment.
Considering the risks involved with hospital stays, treatment at home is often recommended where possible. Nearly all patients with DVT can be diagnosed and treated without requiring hospital admission. For PE, there are tools to identify those who can safely be treated at home too. The Pulmonary Embolism Severity Index (PESI) uses factors like your age, gender, whether you have had cancer, heart failure, lung disease, and your vital signs to predict the severity of your PE. If you have a low PESI score, you can be safely treated for PE at home. The simplified version of PESI defines low-risk patients as those under 80 years old, without significant previous disease conditions, with a pulse rate below 110/min, systolic blood pressure above 100 mm Hg, and blood oxygen level above 90% in room air.
What else can Thromboembolic Event be?
Possible conditions whose symptoms can be similar to Deep Vein Thrombosis or DVT include:
- Cellulitis
- Arterial insufficiency
- Lymphedema
- Hematoma
On the other hand, patients with Pulmonary Embolism or PE could present a variety of symptoms that may resemble other conditions. The following medical issues should be considered when diagnosing PE:
- Congestive heart failure
- Acute respiratory distress syndrome
- Pneumonia
- Myocardial infarction, or heart attack
As a result, the process of evaluating and diagnosing PE must include checks to rule out these other potential medical issues.
What to expect with Thromboembolic Event
According to research, the number one cause of in-hospital health complications and death worldwide is events relating to blood clots, or thromboembolic events. The death rate can also depend on other existing health conditions a patient has. For instance, patients admitted to the hospital for a sudden blood clot, especially a pulmonary embolism (a blood clot in the lungs), with multiple health complications such as heart failure and atrial fibrillation (an irregular heart rhythm that can lead to blood clots), could have an in-hospital death rate as high as 4.5% in the first 30 days following their admission.
In patients with active cancer, this rate can go as high as 10%. A large number of these patients show up in the hospital with a significant and unstable clot condition. Reports show that death from any cause within 30 days of arriving at the hospital with an unstable blood clot in the lungs could occur for up to 14% of patients. Moreover, the rate of getting another clot in the future also depends on the patient’s health condition and factors predisposing them to blood clots.
In fact, a recent study showed that within 5 years, 17.7% of patients with active cancer and 8.6% of those without cancer reportedly had another blood clot event. Due to the high number of blood clot cases reported worldwide every year, and the statistical data relating to deaths and recurring events, there is a need for a thorough review of medical policies related to preventing blood clots. This is necessary to consistently and safely treat those at most risk of the disease.
Even after being diagnosed with a clot, some patients remain at risk for getting another one. Risk factors for recurrent clots are similar to those for the initial event and aren’t just limited to clotting disorders. Recommended methods of predicting the risk for a recurring clot include the Vienna model, the DASH score, and the HERDOO-2 model.
Possible Complications When Diagnosed with Thromboembolic Event
Long-term problems after properly treated Venous Thromboembolism (VTE) are few. After a diagnosis of Deep Vein Thrombosis (DVT), patients might suffer from post-thrombotic syndrome, a common after-effect. This condition often shows up as limb pain and swelling due to chronic venous insufficiency.
Long-term effects of recurrent Pulmonary Embolism (PE) include pulmonary hypertension (high blood pressure in the lungs) and cor pulmonale (right-sided heart failure).
Bleeding is considered a significant and feared complication of VTE treatment. Older patients or those with underlying liver or kidney issues have a higher risk of bleeding. However, despite this risk, routine laboratory monitoring isn’t usually recommended for patients taking newer anticoagulants. For those receiving vitamin K antagonist therapy and having INR (International Normalized Ratio) levels monitored, if their INR level is above 4.5 but below 10 and they have non-significant bleeding, doctors usually recommend temporary discontinuation of the drug rather than reversal therapy.
If a patient develops a life-threatening bleed while taking vitamin K antagonist therapy, injectable vitamin K along with a transfusion of four-factor prothrombin complex concentrates (PCC) transfusion is usually suggested.
For victims of severe bleeding while on newer oral anticoagulant therapy, medical personnel might try transfusing four-factor PCC or infusing factor Xa or inactivated-zhzo. Dabigatran might be preferable in some situations where the risk of severe bleeding is high as idarucizumab can reverse this drug’s effects. It’s crucial to clarify that doctors recommend resuming anticoagulation within 90 days post a major bleeding episode.
Immune-mediated Heparin-Induced Thrombocytopenia (HIT) typically happens 5 to 10 days after exposure to heparin. HIT manifests as clotting and low platelet counts and can be life-threatening. If patients using heparin therapy witness a 50% or more decline in their platelet counts, it is crucial to consider HIT. Tests for antibodies to platelet factor 4 can confirm this diagnosis. If diagnosed with HIT, the patient should stop all heparin products immediately. Some treatments for HIT-associated clotting might include argatroban, bivalirudin, danaparoid, fondaparinux, or a non-vitamin K oral anticoagulant (such as rivaroxaban).
Warfarin-induced skin necrosis is a rare side effect of warfarin therapy, affecting less than 0.1% of the population. A deficiency in Protein C can increase the risk of developing this disorder. If a patient with hereditary Protein C deficiency starts taking warfarin, they might witness a swift decrease in Protein C concentration, leading to temporary hypercoagulability (an increased tendency towards clotting) resulting in microvascular thrombotic occlusions (clots in tiny blood vessels), which can cause skin necrosis.
Important problems to be aware of:
- Post-thrombotic syndrome due to DVT
- Pulmonary hypertension and cor pulmonale from repeated PE
- Severe bleeding
- Increasing the frequency of bleeding in patients with old age or underlying liver or kidney dysfunction
- Heparin-Induced Thrombocytopenia
- Warfarin-induced skin necrosis
Preventing Thromboembolic Event
Research shows that the risk of developing venous thromboembolism (VTE) – a condition where a blood clot forms in a deep vein often in your leg – can be significantly reduced with appropriate preventative measures (prophylaxis). Since most instances of VTE happen when people are hospitalized, the hospital is an ideal place to initiate these preventative measures. Even after surviving an event of VTE and receiving anti-blood clotting treatment, patients are still at risk of experiencing it again, so it’s vital to do everything possible to prevent it in the first place. Estimates suggest that with the right prophylactic measures, the occurrence of VTE can be reduced by 30 to 65 percent without causing more complications related to anti-blood clotting treatment.
For patients with a moderate-high risk of getting VTE who are critically ill, the use of low-molecular-weight heparin (a medicine to prevent or treat harmful blood clots) is advised. However, the risk of VTE can extend past their stay in the hospital. Betrixaban, an oral drug that prevents blood clotting, was recently approved by the U.S Food and Drug Administration to be used as an extended VTE prophylactic for adults admitted to the hospital due to a severe medical condition.
For patients undergoing orthopedic surgery, who have an increased risk of experiencing VTE, the American Academy of Orthopaedic Surgeons (AAOS) provides specific guidelines. The use of blood clot-preventing medicines is advisable for patients at various levels of risk, including those who are at a higher risk for major bleeding. Whether it’s through the use of low-molecular-weight heparin, fondaparinux, apixaban, dabigatran, rivaroxaban, low-dose vitamin K antagonist, or aspirin, the recommended duration for this preventative method is usually 7 to 10 days after the surgery has been performed.
Furthermore, the American College of Chest Physicians (ACCP) states that surgeries for hip fractures, as well as total knee or hip replacements carry a large risk for VTE. For these cases, both non-medication and medication VTE prophylaxis are recommended. In patients at lower risk for bleeding, they suggest continuing their prophylaxis for up to 35 days after surgery. Regular monitoring for VTE using ultrasound is not recommended for patients undergoing orthopedic, general, abdominal-pelvic, or trauma surgery.
