Cardiac Risk in Non Cardiac Surgery

New Insights into Management

Robert J. Herman MD, FRCPCUniversity of Calgary

Outline

Decision making and the principles of testing

Non-Invasive testing

Cardiac risk indices/Prediction Tools

Management algorithms in perioperative care

Risk reduction strategies

Role of the Perioperative Consultant

Risk Assessment Not to “clear” patient for surgery

Objective, algorithmic, evidence-based and reproducible

Risk Reduction or ManagementCardiac, pulmonary, DVT, other

Management of specific perioperative issuesDiabetes, heart failure, atrial fibrillation, infection, etc

The Nature of the Problem

30 Million of people undergoing surgery.

A third with CV disease, most often stable.

Only 2 - 3% ever have an event.

Poor outcome (15-25% in hospital mortality rate)

A Probabilistic Approach to Decision Making

Probability

Test/No Treat Threshold Test/Treat Threshold

DiseaseNo Disease

A Probabilistic Approach to Decision Making

Probability

Test/No Treat Threshold Test/Treat Threshold

DiseaseNo DiseasePost-test Probability

Pre-test ProbabilityTEST

A Probabilistic Approach to Decision Making

Probability

Test/No Treat Threshold Test/Treat Threshold

DiseaseNo DiseasePost-test Probability

Pre-test ProbabilityTEST

Sensitivity = True Positive Rate / Population with the Disease

Specificity = True Negative Rate / Population without Disease

The Preoperative ConsultApplying the Principles

Probability

Test/No Treat Threshold Test/Treat Threshold

DiseaseNo Disease

Pick up the chart76 yr old male

33% OR 0.5

Hx & PE/Apply Prediction ToolT2DM PLR 1.0Previous AMI PLR 3.8

OR 1.966%

Do a MIBI scanSens .83Spec .49PLR 1.63

OR 3.176%

Kertai, M D et al. Heart 2003;89:1327-1334

Copyright ©2003 BMJ Publishing Group Ltd.

Sens 52% Sens 74% Sens 85%Spec 70% Spec 69% Spec 70%

Sens 50% Sens 83% Sens 74%Spec 91% Spec 49% Spec 86%

Optimal ROC

Best studied

The Preoperative ConsultApplying the Principles

Probability

Test/No Treat Threshold Test/Treat Threshold

DiseaseNo Disease

Pick up the chart76 yr old male

33% OR 0.5

Hx & PE/Apply Prediction ToolT2DM PLR 1.0Previous AMI PLR 3.8

OR 1.966%

Do a DSE scanSens .85Spec .70PLR 2.83

OR 5.484%

What is the Question?Beta Blocker/No BB

What is the evidence that treating patients with CAD in the perioperative period

saves lives or prevents AMI?

Revascularization versus Medical Therapy for Vascular Surgery - CARP Study

(McFalls, NEJM 2004, 351(27):2795-804)

RCT of 510 patients undergoing elective vascular surgery with 1 or more coronary lesions ≥ 70% by angiogram.

Excluded patients (91% of those screened): urgent surgery, severe coexisting illness, revascularized, without any symptoms, left main >50%, EF <20% or Aortic stenosis

Majority taking BB (84%), ACE inhibitors, statins and ASA.

Median follow-up 2.7 years

22%23%

Caution must be exercised because the study excluded pts with > 50% LMCAD,

EF < 20% and Aortic stenosis

What percentage of those with surgical disease are asymptomatic and, as such, would not be

picked up by 1 of the Prediction Tools?

What is the evidence that treating patients with asymptomatic (even flow limiting left main) CAD

is beneficial?

Common Themes of the Various Management Algorithms

Patchwork of evidence and expert opinion

If surgery is an emergency, proceed with surgery regardless of risk.

Identify low risk patients - further evaluation is not necessary.

Identify high risk patients - further testing may be necessary, but more importantly, manage the risk through prophylaxis.

Lee and GoldmanRevised Cardiac Risk Index

Lee et al. Circulation 1999;100:1043-9

1. High risk surgery intraperitoneal, thoracic and supra-inguinal vascular

2. History of IHD prior MI, angina, Q-waves on ECG, use of nitrates

3. History of heart failure4. History of cerebrovascular disease5. Preoperative treatment with insulin6. Serum creatinine greater than 153 mMol/L

RCRI Probability

0 0.4%1 0.9%2 7%

3 or more 11%

ACC/AHA Guidelines (2002)

Clinical predictorsMajor: MI within 1 mo, UA, positive ischemia, decompensated

CHF, symptomatic arrhythmia, high-grade AV block, severe valvular disease

Intermediate: MI > 1 mo, compensated CHF, Cr > 153, DMMinor: Age, abnormal ECG, non NSR, low functional capacity,

CVA Hx, uncontrolled HTN

Functional capacity4+ MET (4 blocks/2 flights, flight w/groceries, level ground 6.4

km/hr, run short distance, scrub floors, golf, swim, tennis)

Surgery-specific riskHigh: Aortic, vascular, PVD, emergent, prolonged ± high EBLIntermediate: peritoneal, thoracic, CEA, H&N, ortho, prostateLow: endoscopy, cataract, breast

Leads to:– Cancellation/delay surgery– Risk of investigation and

revascularization, itself– Unnecessary care

High Risk Surgical ProceduresEmergent major procedures, esp in the elderlyAortic or other major vascular surgeryPeripheral vascular surgeryProlonged surgical time or likely to have +++ EBL

Lee and GoldmanRCRI of 0 or 1

Consider risk/benefit of investigation & RxDo not test unless, if (+), you plan to interveneChoose an approp test to answer the question

- Angio if LMCAD, 2-3 vessel CAD with ↓EF- ETT or Dobutamine Echo to assess LV fxn

Lee and GoldmanRCRI 2 or more

What is the role for noninvasive testing?

Almost NONE

When would you cancel surgery and revascularize the patient?

SIMPLE1) When it is a very high risk pt and you would take

them irrespective of the planned surgery, in which case, revascularization pre-empts the procedure.

2) When the risks of taking the patient to the OR are greater than the combined risks of delaying surgery, investigating for CAD, treating it and the eventuality that the patient may never actually return to have their initial problems attended to.

Risk Reduction Strategies

Beta-blockers

Calcium channel blockers

Alpha-2 agonists

ASA

Lipid Lowering (statin)

Prevention of stress hyperglycemia

Mangano StudyRCT, N=200, known MI/angina or 2 risk factors

(Age ≥ 65, HTN, Smoking, TC >6.2, DM)

Atenolol 30m pre-op, 7 post-op, titrated to HRPrimary outcome: all cause mortality at 2 yr

9% versus 20.8%, P=0.019, NNT = 8.5

Mangano DT. N Engl J Med 1996; 335:1713-20

DECREASERandomized, unblinded, pts for vasc surgery,N=112 Risk factor + pos DSE

(>70 y.o., angina, MI, CHF,Ventricular arrhythmia, DM, limited fxn)

Bisoprolol 5-10mg, titrated to HR, 30 d pre & post-op.Endpoint: post-op cardiac death or MI at 30 daysResults: RR 10-fold, 3.4% vs 34%, P<0.001, NNT 3.3

Poldermans D. N Engl J Med 1999; 341:1789-94

Beta-blockade in DMDiabetic Postoperative Mortality and Morbidity Trial

(DIPOM)

N=921, Metoprolol CR the evening pre-op, titratedPrimary outcome: AMI/death/UA/CHF at 6 mosContinued to 18 months

Reported at Late Breaking Trials at AHA 2004 as a negative study; has never been published

Copyright ©2005 BMJ Publishing Group Ltd.

Devereaux, P J et al. BMJ 2005;331:313-321

Risk for a Major Perioperative Cardiovascular Event (CV death, non-fatal AMI, or non-fatal cardiac arrest)

with or without Beta Blocker Treatment

Calcium Channel Blockers(Wijeysundera et al, Anesth Analg 2003;97:634-41)

Meta-analysis 11 RCT, (1007 patients)

No significant difference between CCB and control for total mortality or AMI.

RRR in cardiac ischemia 51% (20 - 70%)

RRR in SVT 48% (28 - 63%)

Data is strongest for diltiazem

Alpha 2 Agonists(Wijeysundera et al, Am J Med 2003;114:742-52)

Meta-analysis of 23 RCT (3395 patients)

Overall RRR for mortality 36%, (1 - 58%)24% RRR in periop ischemia, no effect on AMI

Also beneficial during vascular surgery

No effect in cardiac surgery

ASA

Traditional recommendations: stop 7-10 days preop to allow time to renew circulating pool of platelets

ArgumentsAgainst continuing ASA

– Fatal bleeding complications previously described (intracranial surgery and TURP)

– Withholding perioperative ASA would add risk to 0.3 patient/1000 pt per week

For continuing ASA– Rebound phenomenon plus the prothrombotic state of

surgery, itself, may predispose to clotting– 10.2% of ACS occur in the setting of withdrawal– Most document increase in bleeding of 1.5 fold, but

only in minor bleeding

Statins(Durazzo et al, J Vasc Surg 2004;39:967-76)

Observational studies showed benefit of statin therapy (Poldermans 2003, Kertai 2004, Lundenauer 2004)

RCT of 100 pts undergoing vascular surgery (atorvastatin 20mg vs. placebo for 45 days)

Outcome: 6 month composite cardiac outcome 26.0% vs. 8.0% favoring Rx; P =.031, NNT 5.5