ANESTHESIA FOR NON CARDIAC SURGERY IN PATIENTS WITH CORONARY STENTS
Dr. Mahesh VakamudiProfessor and HeadDepartment of Anesthesiology, Critical Care and Pain Medicine (ISO 9001:2008 CERTIFIED)Sri Ramachandra UniversityChennai
Magnitude of the problem
2 million patients undergo PCI annually
90% of these patients receive one or more intracoronary stents
5% of these patients will undergo non cardiac surgery in the first year after stenting
Coronary artery bypass
surgeries
Percutaneous coronary
interventions
NUMBER
>Stents
commonly placed
Increase procedural
successDecrease restenosi
s
Why this lecture?
In patients who have coronary stents, perioperative coronary stent thrombosis is a catastrophic complication
Non cardiac surgery, especially if surgery is performed immediately after stenting and particularly if dual antiplatelet therapy is discontinued – increases this risk
Maintain balance between risk of bleeding and stent thrombosis is our dilemma.
What do we do? That’s what this lecture is about
Which patients are prone for stent thrombosis? Patients with a suboptimal
angiographic result Those with high risk lesions
Small vessels Bifurcation lesions
Those with diabetes and renal failure Those whose dual antiplatelet
therapy has been stopped
Scoring system for LST
Risk score for prediction of LST
Renal failure 6 pointsBifurcation lesion 6 pointsDiabetes 4 pointsBrachytherapy 2.5 pointsEach 20% fall in EF 0.25 points
Low0 6 9 1
319
Medium High Very High
Why thrombosis?
Stents not endothelializ
ed
Prothrombotic state due to surgery
Stopping antiplatelets
STENT THROMBOSIS
Early surgery
Discontinuation of Aspirin and Clopidogrel
Loss of antiplatelet effect
Rebound increase in COX 1 and
TXB2Increased
thrombin and decreased fibrinolysis
Surgery Prothrombotic state
Loss of anti-inflammatory protection
by clopidogrel
Stent thrombos
is
MI⁺ &
Coronary angioplasty
without stents
Abrupt vessel collapse due to acute recoil and
vasospasm
Bare metal stents
Stent placement injures vessel wall and causes scar
tissue growth inside the stent
Stent restenosi
s
Drug eluting stents
Platform + Carrier
(Stent + Drug)
Antiproliferative and immunosuppressive
properties
Prevent neointimal hyperplasia
Delay endothelializati
onbut
Late stent thrombosis
Incidence of deaths
Bare metal stents
Kaluza GL, Joseph J, Lee JR, Raizner ME, Raizner AE. Catastrophic outcomes of noncardiac surgery soon after coronary stenting. J Am Coll Cardiol 2000;35:1288 –94.
8 out of 25 patients who underwent surgery within 2 weeks died – 7 of
MI, 1 of bleedingNone out of 15 patients who underwent surgery after 15 days
died
Wilson SH, Fasseas P, Orford JL, et al. Clinical outcome of patients undergoing noncardiac surgery in the two months following coronary stenting. J Am Coll Cardiol 2003;42:234–40.
The risk of death, MI, or stent thrombosis was elevated for 6 weeks, not for just 2 weeks
Sharma AK, Ajani AE, Hamwi SM, et al. Major noncardiac surgeryfollowing coronary stenting: when is it safe to operate? CatheterCardiovasc Interv 2004;63:141–5.
Of 27 patients who underwent non cardiac surgery within 3 weeks of BMS, 86% of those who stopped antiplatelets died
Bare metal stents
DES
First generation DES elute Sirolimus Paclitaxel
Second generation DES elute Zotarolimus Everolimus
Nasser et al. (20) reported sirolimus-eluting stent (SES) thrombosis in 2 patients after surgery
performed 4 and 21 months after SES implantation.
McFadden et al. (19) reported DES thrombosis in 3 patients undergoing surgery late (343 to 442
days) after implantation.
Drug eluting stents
Avoid preoperative coronary stenting
Stent selection (BMS vs DES)
Delay surgery
Optimize antiplatelet therapy
Education and collaboration
Avoid preoperative coronary
revascularization, unless there exists a strong and proven
indicationConsider balloon angioplasty if
surgery is needed within 6 weeks.
Avoid stents
Choose BMS ifSurgery needed from
6 weeks to 12 months
Bleeding diathesisPatient unable or unwilling to receive
long term clopidogrel
Choose DES if surgery is
needed after 12 months
BMS – 6 weeksDES – 12 monthsContinue
antiplatelet therapy during
surgerySurgeonsanesthesiologi
sts cardiologists
Avoiding revascularization CARP trial 510 stable patients with CAD
undergoing major vascular surgery Randomized to revascularization (by
CABG or PCI) or no revascularization Similar incidence of postoperative MI
and 27 month survival in both the groupsSo, first ask the question:
Is revascularization necessary?
Revascularization without stents (Balloon only) Patients with acute coronary
syndrome and those with profound ischemia on non invasive testing do need revascularization
Can be done without stents: Percutaneous balloon angioplasty
In this study, when surgery was done 11 days after PCI, only 1 patient died and 1 had an AMIGottlieb A, Banoub M, Sprung J, Levy PJ, Beven M, Mascha EJ.
Perioperative cardiovascular morbidity in patients with coronary arterydisease undergoing vascular surgery after percutaneous transluminalcoronary angioplasty. J Cardiothorac Vasc Anesth 1998;12:501– 6.
When surgery after Balloon angioplasty? 2002 ACC AHA guidelines Delaying noncardiac surgery for 6 to 8
weeks was discouraged because restenosis could have occurred
Performing noncardiac surgery too early after the PCI also may be risky because acute or subacute closure after balloon angioplasty usually occurs within hours to days after the procedure.
Delay surgery for 1 week after balloon angioplasty
If stenting can’t be avoided Complex lesion or inability to achieve optimal
result with balloon angioplasty Choose the right stent Surgery needed with 12 months: Choose BMS Surgery can be delayed for > 12 mth: DES BMS endothelialize more rapidly than DES Sirolimus eluting stent preferable as it
requires 3 mths of antiplatelet therapy than a paclitaxel eluting stent that requires 6 mths of clopidogrel
Delay surgery
6 weeks BMS 12 months DES
Time from stent until surgery (months)
Major adverse cardiac events (%)
10
8
6
4
2
02 4 6 8 1
012
14
16
18
0
Bare metal stents
Drug eluting stents
RISK OF PERIOPERATIVE STENT THROMBOSIS WITH DES
Stents implanted in left main coronary arteryStents implanted in bifurcations
Greater total stent length (multiple/overlapping stents)
Heightened platelet activity (surgery, DM, malignancy)
In stent restenosisLeft ventricular dysfunction
Localized hypersensitivity vasculitisPenetration by stent into necrotic core
Plaque disruption into non stented segmentRenal failure
Diabetes mellitusResistance to antiplatelets
Inappropriate discontinuation of antiplatelet medications
What are the steps to prevent stent thrombosis in these patients coming for non
cardiac surgery?
Periop antiplatelet therapy Continue dual antiplatelet thearpy
during and after surgery Discontinue clopidogrel but “bridge”
the patient to surgery with Glycoprotein IIb/IIIa inhibitor or an antithrombin, and restart clopidogrel as soon as possible after surgery
Discontinue clopidogrel before surgery and restart it as soon as possible after surgery
Impact of aspirin on bleeding Most studies in cardiac and vascular
surgery Safe in doses of 75 – 150 mg Increases bleeding by a factor of 1.5,
no effect on morbidity and mortality Avoid in TURP and intracranial
surgery (as bleeding in these situations can be life threatening)
Continue aspirin monotherapy in
elective non cardiac surgery
Option 1 : Continue therapy Dental extractions Cataract surgery Dermatologic surgery
Option 2: Bridging therapy Bridge using short acting antiplatelet
or an anticoagulant Platelet inhibitors are the more
logical choice as stent thrombosis is a platelet mediated phenomenon
Cessation of heparin in a patient not on antiplatelets can cause rebound effect and stent thrombosis
Bridging therapy
A shortacting GP IIb/IIIa inhibitor (tirofiban or eptifibatide) or thrombin inhibitor, or both, is substituted for clopidogrel during the perioperative period
Role Prevent platelet aggregation Displace fibrinogen from GP IIb/IIIa
receptors Block signaling processes
Bridging therapy
Tirofiban and eptifibatide are administered parenterally
Have half-lives 2 h Eliminated by renal clearance. Infusion rate is reduced by half in
patients with reduced renal function Platelet function returns to 60%–90%
of normal after the infusion is stopped for 6–8 h.
When bridging therapy?
Surgeries with high risk of bleeding Intracranial Spinal Retinal
Other drugs
Reversible P2Y12 receptor antagonists are undergoing clinical trials
Cangrelor is a parenteral, reversible direct P2Y12 inhibitor
Half-life of 5–9 min allows 100% recovery of platelet function 1 h after the infusion is discontinued
4 mcg/kg/min infusion achieves complete platelet inhibition when measured at 4 min
AZD6140 is an oral, reversible direct P2Y12 receptor antagonist with a half life of 12 hrs.
Problems with bridging therapy Expensive Logistically difficult Exposes patients to risks associated
with a prolonged hospitalization Some claim that it confers no
protection against intraoperative stent thrombosis
Option 3: Stop antiplatelets Neurosurgery Restart clopidogrel after surgery 600 mg loading dose – Maximal
inhibition of platelet aggregation in 2 – 4 hours (takes 6 hrs with 300 mg)
Reduces the incidence of hyporesponsiveness to platelets (which are activated due to surgery)
Anesthetic drugs metabolized by CYP3A4
like midazolam can irreversibly inhibit this
enzyme which metabolizes clopidogrel
into its active form, modulating its
antiplatelet effect
Steps: Preoperative evaluation
Determine the type of stent: BES, SES, PES When were stents implanted? Determine location of stent in coronary
circulation How complicated was the revascularization? Is there a previous history of stent thrombosis? What antiplatelet regimen is being followed? Determine co-morbidities? What is the recommended duration of
antiplatelet therapy for this patient? Co-ordinate with cardiologist
Steps
Perform procedure in centers where there is 24 hr interventional cardiology coverage for emergency PCI
Intraop management
Tight hemodynamic control Use of beta blockers Good HR control Good BP control Decrease sympathetic outflow and
therefore decrease platelet activation
Regional anesthesia in patients on antiplatelets Advantages
Attenuation of hypercoagulable state Systemically absorbed LA have
antiplatelet effect Follow ASRA guidelines For patients receiving bridging
therapy with eptifibatide or tirofiban, 8 h must elapse before a neuraxial blockade can be performed
Management of stent thrombosis ST segment elevation acute
myocardial infarction Reperfusion Thrombolytic therapy less effective
than primary PCI Platelet mediated phenomenon Risk of bleeding
All that is required during PCI is aspirin and one dose of heparin or bivalirudin
Role of platelet transfusion Transfused platelets are not inhibited
by serum therapeutic levels of antiplatelets
The thrombogenic surface of stents may attract and activate donor platelets to an even greater extent than endogenous plateletsPlatelet transfusions to be avoided
except in instances of life threatening bleeding
Algorithm for patients with DES for NCSEmergen
cySemi
emergencyElectiv
eAssess risk of
bleedingLow Intermediat
eHigh
Length of DAPT< 1 yr
> 1 yr
Stop clopidogrelContinue LD
aspirinProceed
with surgery
DES > 1 yr
DES < 1 yr
Continue DAPT
Stop Anti PLT
Assess risk of thrombosis
Low HighHosp Admn ? IV Anti PLT
STOP
Education In a survey of anesthesiologists, 63%
were not aware of recommendations about the appropriate length of time between stent placement and a subsequent surgical procedure, and one-third recommended no delay or a delay of only 1 to 2 weeks, which is insufficient for BMS, and even more so for DES
Patterson L, Hunter D, Mann A. Appropriate waiting time fornoncardiac surgery following coronary stent insertion: views of Canadiananesthesiologists. Can J Anaesth 2005;52:440 –1
Take home points
Many patients come for non cardiac surgery after PCI
Stent thrombosis is a catastrophe Remember the stepwise approach to
the issue
Avoid preoperative coronary stenting
Stent selection (BMS vs DES)
Delay surgery
Optimize antiplatelet therapy
Education and collaboration
Thank you