Periprocedural risk of thromboembolic events

Consult the patient’s usual medical practitioners to identify risk factors that affect the periprocedural risk of a thromboembolic event. The practitioner who prescribed the antithrombotic therapy should advise on the indication for therapy and the thromboembolic event risk if antithrombotic therapy is interrupted.

Factors that increase the risk of a periprocedural thromboembolic event include:

history of ischaemic stroke, transient ischaemic attack or venous thromboembolism
existing atrial fibrillation, left ventricular thrombosis, a mechanical heart valve or mitral stenosis
factors included in risk indices such as the CHA₂DS₂-VASc score
certain types of surgery (eg coronary artery bypass graft [CABG], carotid endarterectomy)Douketis, 2022.

The risk of a periprocedural thromboembolic event in a patient taking oral antithrombotic therapy for a mechanical heart valve, atrial fibrillation or venous thromboembolism is outlined in Suggested risk stratification for a periprocedural thromboembolic event in a patient with a mechanical heart valve, atrial fibrillation or history of VTE. Use clinical judgement to assess the risk of a thromboembolic event in patients taking antithrombotic therapy for other indications.

Table 1. Suggested risk stratification for a periprocedural thromboembolic event in a patient with a mechanical heart valve, atrial fibrillation or history of VTE[NB1]
Risk category	Patient with a mechanical heart valve	Patient with atrial fibrillation	Patient with a history of VTE
High risk of arterial or venous thromboembolism [NB2] [NB3]	any mechanical mitral valve caged ball or tilting disk valve in mitral or aortic position stroke or TIA in the past 3 months	CHA₂DS₂-VASc score of 7 or more, or CHADS₂ score of 5 or 6 [NB4] stroke or TIA in the past 3 months rheumatic valvular heart disease	VTE in the past 3 months, especially VTE in the past 1 month severe thrombophilia (deficiency of protein C, protein S or antithrombin; homozygous factor V Leiden or prothrombin gene mutation, or double heterozygous for each mutation; multiple thrombophilias) antiphospholipid syndrome associated with vena cava filter active cancer associated with a high risk of VTE [NB6]
Intermediate risk of arterial or venous thromboembolism [NB2] [NB3]	bileaflet aortic valve with major risk factors for stroke [NB5]	CHA₂DS₂-VASc score of 5 or 6, or CHADS₂ score of 3 or 4 [NB4]	VTE in the past 3 to 12 months recurrent VTE nonsevere thrombophilia (heterozygous factor V Leiden or prothrombin gene mutation) active cancer or a history of cancer within 5 years (excluding nonmelanoma skin cancer) [NB6]
Low risk of arterial or venous thromboembolism [NB2] [NB3]	bileaflet aortic valve without major risk factors for stroke [NB5]	CHA₂DS₂-VASc score of 1 to 4, or CHADS₂ score of 0 to 2 (and no prior stroke or TIA) [NB4]	VTE more than 12 months ago
Note: TIA = transient ischaemic attack; VTE = venous thromboembolism NB1: The risk stratification in this table is empirical; there are no clinical prediction models validated in this setting. Some types of surgery may also increase thromboembolic risk (eg coronary artery bypass graft [CABG], carotid endarterectomy). NB2: Arterial thromboembolism refers to stroke and systemic embolism for patients with atrial fibrillation or a mechanical heart valve. Venous thromboembolism encompasses deep vein thrombosis and pulmonary embolism. NB3: High risk is more than 10% per year risk of arterial thromboembolism, or more than 10% per month risk of VTE. Intermediate risk is 4 to 10% per year risk of arterial thromboembolism, or 4 to 10% per month risk of VTE. Low risk is less than 4% per year risk of arterial thromboembolism, or less than 2% per month risk of VTE. NB4: See Clinical risk factors for stroke, transient ischaemic attack and systemic embolism in the CHA2DS2-VASc score for a description of the CHA₂DS₂-VASc score. CHADS₂ score derives from adding together the following points: 1 point each for age more than 75 years, hypertension, diabetes mellitus, heart failure; 2 points for previous stroke or transient ischaemic attack. NB5: The major risk factors for stroke include atrial fibrillation, prior stroke or transient ischaemic attack, hypertension, diabetes, congestive heart failure and age 75 years or older. NB6: Active cancers associated with a high risk of VTE include pancreatic, primary brain, gastric and oesophageal cancer, and myeloproliferative disorders. Reproduced with permission from Douketis JD, Spyropoulos AC, Murad MH, Arcelus JI, Dager WE, Dunn AS, et al. Perioperative Management of Antithrombotic Therapy: An American College of Chest Physicians Clinical Practice Guideline. Chest 2022;162(5):e207-e43.[URL]