1.6 Anticoagulation in the perioperative setting

10.1055/b-0038-164247

1.6 Anticoagulation in the perioperative setting

Lauren J Gleason, Adeela Cheema, Joseph A Nicholas

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1 Introduction

The common presence of anticoagulant and antiplatelet agents in fragility fracture patients (FFPs) presents unique challenges in the perioperative period. Management decisions typically involve balancing short-term bleeding and thrombosis risks and considering the use of bridging anticoagulant therapy. Delaying surgery to manage the effects of these medications can increase the likelihood of adverse events, such as delirium, pneumonia, pressure ulceration, and mortality [1–3]. In the immediate perioperative period, the risks of bleeding often outweigh the risks of thrombosis for most older adults.

Standards of care and published guidelines in this area vary widely throughout the world. This chapter reflects the principles for anticoagulation management in the perioperative period, with specific recommendations based on current US and European approaches. Consultation with local guidelines may be necessary to align practice with other national or regional standards.

2 Perioperative anticoagulant management

2.1 General approach

There are four considerations in the management of antithrombotic agents in the perioperative period [4]:

The short-term risk of acute thromboembolism if the anticoagulation/antiplatelet agent is discontinued
The risk of major bleeding from the procedure if the anticoagulation/antiplatelet agent is continued
The effectiveness, availability and safety of reversal agents (eg, plasma and vitamin K)
The overall need to minimize surgical delay and maximize mobility

Additionally, part of the preoperative assessment should include the procedure-specific bleeding risk, and the anticipated consequences of bleeding if anticoagulants are resumed during this time. For example, percutaneous screw fixation has a much lower risk of bleeding than that of hip arthroplasty, and the harm of continuation or early resumption of long-term anticoagulation is presumed to be lower than for patients treated with arthroplasty or implant fixation [5].

2.2 Anticoagulants and antiplatelet agents

Both anticoagulants and antiplatelet agents interfere with thrombus formation. Anticoagulant medications (eg, warfarin, heparin, apixaban, dabigatran, and rivaroxaban) interfere with the coagulation cascade and clotting factors, while antiplatelet agents (eg, aspirin, and clopidogrel) target platelets. While all of these agents can contribute to clinically significant blood loss, anticoagulants are generally more potent at preventing venous, arterial or intracardiac thrombosis, and are also more likely to cause serious postoperative bleeding. Specific indications and issues are detailed below. Figure 1.6-1 shows the mechanism of action of some of these agents.

**Fig 1.6-1** Sites of action of various anticoagulant medications.

2.3 Reasons for use

In order to assess the risk of short-term cessation of anticoagulant or antiplatelet medications, it is important to determine the a priori indication for their use.

Older adults are often anticoagulated for various medical conditions including atrial fibrillation (AF), venous thromboembolism (VTE) (eg, hypercoagulable states, deep vein thrombosis [DVT], pulmonary embolism [PE]), and prosthetic heart valves, each of these indications having a different short-term risk of thrombosis during the perioperative period.

2.4 Thrombotic risk assessment by indication

After confirming the indication for anticoagulation, it is important to determine the short-term risk of thrombosis when stopping an anticoagulant. Note that the risk of thromboembolism for these indications is typically reported as an annual risk; for most patients the short-term risk during a typical perioperative period is assumed to be much lower.

2.4.1 Atrial fibrillation

The most common indication for anticoagulant use in the older adult population is for prevention of thromboembolic strokes in nonvalvular AF.

The risk of thromboembolism varies and can be estimated by the CHADS₂ and the enhanced CHA₂DS₂-VASC scores [6, 7]. The relevant criteria and associated risk of stroke are shown in Table 1.6-1 and Table 1.6-2 .

**Table 1.6-1** The CHADS₂ can be used to estimate the risk of thromboembolism.
	Risk factor	Point value	Total score	Annual stroke risk, %
C	Congestive heart failure	1	0	1.9
H	Hypertension—blood pressure consistently above 140/90 mm Hg (or treated hypertension on medication)	1	1	2.8
A	Age ≥ 75 years	1	2	4
D	Diabetes mellitus	1	3	5.9
S2	Prior stroke or TIA or thromboembolism	2	4	8.5
			5	12.5
			6	18.2
Abbreviation: TIA, transient cerebral ischemia attack.

**Table 1.6-2** CHA₂DS₂-VASC score and stroke risk to estimate the risk of thromboembolism.
	Risk factor	Point value	CHA₂DS₂-VASC total score	Stroke risk, % per year
C	Congestive heart failure (or left ventricular systolic dysfunction)	1	0	0
H	Hypertension—blood pressure consistently above 140/90 mm Hg (or treated hypertension on medication)	1	1	1.3
A	Age: ≥ 75 years	2	2	2.2
D	Diabetes mellitus	1	3	3.2
S2	Prior stroke or TIA or thromboembolic event	2	4	4
V	Vascular disease (eg, peripheral artery disease, myocardial infarction, aortic plaque)	1	5	6.7
A	Age: 65–74 years	1	6	9.8
Sc	Female gender	1	7	9.6
			8	12.5
			9	15.2
Abbreviation: TIA, transient cerebral ischemia attack.

2.4.2 Venous thromboembolism

In those with venous thromboembolism, the risk of recurrent thrombosis, thrombus propagation, and embolization is greatest in the first 3 months after the diagnosis and initiation of therapy [8]. This risk also varies depending on whether the VTE was provoked, unprovoked, or resolved.

2.4.3 Mechanical heart valves

Patients with mechanical heart valves are at significantly increased long-term risk for embolic stroke. The risk varies by the type, number, and location of prosthetic valve and associated medical conditions ( Table 1.6-3 ) [9].

**Table 1.6-3** American College of Chest Physicians (ACCP) suggested risk stratification for perioperative thromboembolism. Reproduced from Douketis et al **[10]** with permission of the ACCP.
Risk category	Mechanical heart valve	Atrial fibrillation	Venous thromboembolism
High
> 10%/year risk of ATE OR > 10%/month risk of VTE	Any mechanical mitral valve Older aortic valve Recent (< 6 months) stroke or TIA	CHADS₂ score of 5 or 6 Recent (< 3 months) stroke or TIA Rheumatic valvular heart disease	Recent (< 3 months) VTE Severe thrombophilia
Moderate
4–10%/year risk of ATE OR 4–10%/month risk of VTE	Bileaflet aortic valve and one of the following: Atrial fibrillation Prior stroke/TIA Hypertension Diabetes Heart failure Age > 75 years	CHADS₂ score of 3 or 4	VTE within past 3–12 months Recurrent VTE Nonsevere thrombophilic conditions Active cancer
Low
< 4%/year risk of ATE OR < 2%/month risk of VTE	Bileaflet aortic valve without atrial fibrillation and no other risk factors for stroke	CHADS₂ score of 0–2 (and no prior stroke or TIA)	Single VTE within past 12 months AND No other risk factors
Abbreviations: ACCP, American College of Chest Physicians; ATE, arterial thromboembolism; TIA, transient cerebral ischemic attack; VTE, venous thromboembolism.

2.5 Bleeding risk assessment

Older adults are prone to bleeding in general and many adults at relatively high risk for thrombosis also have an elevated risk for bleeding. Cardiovascular aging, comorbidity and some medications can result in friable blood vessels and prolonged postoperative bleeding after orthopedic surgery. In addition to procedure-specific risk estimates, there are different prediction tools to evaluate bleeding risk in individual patients [11–13]. The HAS-BLED score [12] evaluates 1-year risk of major bleeding (defined as intracranial bleeding, bleeding requiring hospitalization, hemoglobin decrease > 2 g/L, and/or transfusion) in patients with AF (see Table 1.6-4 ). There are no well-validated predictors for short-term bleeding risks, but the risk factors in the HAS-BLED tool are likely relevant in the perioperative setting as well.

**Table 1.6-4** HAS-BLED score to evaluate 1-year risk of major bleeding.
	Risk factor	Point value	HAS-BLED total score	Bleeds per 100-patient years
H	Hypertension (systolic blood pressure > 160 mm Hg)	1	0	1.13
A	Abnormal renal function (long-term dialysis, renal transplant, serum creatinine > 2.4 mg/dL) Hepatic function (chronic hepatitis, bilirubin > 2× upper normal with liver enzymes > 3× upper normal)	1 1	1	1.02
S	History of stroke	1	2	1.88
B	Bleeding (ie, major bleeding history)	1	3	3.74
L	Labile INRs (ie, therapeutic range < 60% of time)	1	4	8.7
E	Elderly (≥ 65 years old)	1	5	12.5
D	Drugs (concomitant antiplatelet, NSAIDs) Alcohol consumption > 8 drinks/week	1 (each)	> 5	Insufficient data
Abbreviations: INR, international normalized ratio; NSAID, nonsteroidal antiinflammatory drug.

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Tags: Orthopaedics and Trauma Surgery, Osteoporotic Fracture Care, Section 1 Principles

May 17, 2020 | Posted by drzezo in ORTHOPEDIC | Comments Off

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1.6 Anticoagulation in the perioperative setting