Attempt to identify low risk subgroup who do not need stratification beyond clinical assessment in the office. Low risk (<1% of post-op cardiac event or death) found in patients with:

• Good cardiac functional status (i.e. functional class I or class II, see below)
• lack of CAD (i.e. no Qs on ECG, no angina)
• low score on multifactorial index (i.e. no active CHF or arrhythmia, or metabolic
  abnormalities). Cannot use risk indices alone as 40% of severe complications occur in
  group with original Goldman score < 13.

Thus, important to consider pre-test probability of active CAD, even if "low risk" by multifactorial index. Risk also increases with age independent of increased prevalence of cardiac conditions. Functional status and prior h/o CAD or peripheral vascular disease (PVD) help to define risk.

• <Functional Status: Class IV- angina at rest or with minimal activity (e.g. dressing)
• Class III-can perform simple activities, like bowl, push a power mower, do the laundry,
  but can't have sexual intercourse without stopping, garden or walk at 4 mph.
• Class II-can do all above, but can't carry a 20# load up a flight of stairs, or jog at 5 mph
• Class I-no symptom limited activities

Duration of surgery is not important risk factor unless significant blood loss anticipated. Risk impacted more by pain control, volume status, hypoxia and catechols from stressors (i.e. factors causing tachycardia). Also, risk greatest with general anesthesia and spinals, both of which cause vasodilation (not unlike persantine in persantine-thal stress test). Regional associated with lowest risk.

Since tachycardia (the best correlate of intraoperative ischemia, and thus, MI) is an important stressor, stratification should include this variable. Routine ETT is a good test when not contraindicated by LVH, dig effect or LBBB. In these cases, or when functional capacity not definable (e.g. orthopedic condition limits activity), dobutamine echo or persantine-thal apt. When functional eval limited by PVD, low threshold for stratification, as most are in moderate to high risk group of CAD. DM may be associated with aSx CAD and has been defined as a risk factor for post-op cardiac complications (need to keep this in mind when deciding when to stratify).

Cath for PTCA or CABG only when meet general indications. E.g. pt. with chronic stable angina of functional class II or less (with or without Rx) are low risk, and thus, event rate post cath is 2%, greater than their operative risk. Time surgery as remote as possible from an MI (with current anesthetic techniques and peri-operative care, cardiac complications post MI are 5-10% by 1 month and down to 1-2% by 3 months.).

When active CHF present, delaying surgery to optimize Rx will decrease risk. Echo helpful only if necessary in Dx/management of CHF, or if necessary to confirm h/o CAD or evidence of valvular disease. If valvular disease severe, may need to postpone surgery until after valvuloplasty/valve replacement.

Only high grade conduction abnormalities require a pacemaker. Indications same as non-surgical population. Same true for arrhythmias. If ventricular, treat underlying cause; if SVT, treat if Sx.

Mild-Moderate htn (DBP<110) not predictive of post-op lability. DBP > 110 mm Hg associated with risk of both post-op Htn and hypotension. Thus, when DBP > 110, imperative to control pre-op. May want to adjust meds upward for mild-moderate Htn pre-op, but do not need to delay surgery to do so.

Medications:

• Generally continue ß-blockers (if need to d/c abruptly, rarely causes reflex w/d Sx); generally will start pre-op ß-blockers in those with cardiac risk factors, or known CAD (see Mangano, NEJM 1996 and Poldermans et al, NEJM 341: 1789, 1999)
• Pre-op dig proph for SVT/CHF/Valvular disease if helps Sx
• Coumadin held 3-4 d pre-op. If recent (< 1mo) DVT or acute arterial embolism convert to heparin pre-op, and resume post-op. Otherwise SC heparin okpost-op except in subacute DVT (1-3 mo. post event, use IV heparin). May resume PO coumadin on 3rd post-op day, assuming no prior bleeding.
• Oral Hypoglycemics (Sulfonylureas and metformin) may need to be modified, depending on likely duration of NPO. Baseline morning insulin dose is usually cut in half.
• Anti-hypertensives usually continued without change, except loop diuretics which may need to be decreased or held, depending on pre-op volume status.

Post-Op Findings suggestive of cardiac events:

• MI presenting with CP in only 50% due to anesthesia/analgesia (CHF, hypotension, arrhythmia and delta MS in other half)
• Most post-op MIs within 48 hours, but CHF and Htn may be delayed to days 3-5 post-op due to mobilization of third spaced fluids.
• Post-op Htn occurs in 5% as new onset & 25% of pre-hypertensives. Focus on pain control & fluid overload prior to adjusting meds

References:

1. Eagle KA, et al. Current Problems in Cardiology. 5/96, 290-382 (an exhaustive review)
2. Eagle KA, Brundage BH, Chaitman BR, et al. Guidelines for Perioperative Cardiovascular Evaluation for Noncardiac Surgery. JACC 1996;27:910-948. ( Eagle et al., abridged version of above, Mayo Clin Proc. 1997; 72: 524-531)
3. Detsky AS et al. Predicting cardiac complications in patients undergoing non-cardiac surgery. J Gen Int Med 1986;1:211-219.
4. Mangano DT, Layug EL, Wallace A and Tateo I. Effect of Atenolol on Mortality and Cardiovascular Morbidity after Noncardiac Surgery. NEJM 1996; 335: 1713-1721.
5. Mangano DT, and Goldman L. Preoperative Assessment of Patients with Known or Suspected Coronary Disease. N Engl J Med 1995;333(26):1750-1756.
6. Poldermans D., et al. The Effect of Bisoprolol on Perioperative Mortality and Myocardial Infarction in High-Risk Patients Undergoing Vascular Surgery N Engl J Med 1999; 341:1789-1794, Dec 9, 1999.
7. Kearon C., Hirsh J. Current Concepts: Management of Anticoagulation before and after Elective Surgery.N Engl J Med 1997; 336:1506-1511, May 22, 1997.

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