Preoperative cardiac risk assessment

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor-In-Chief: Mohammed A. Sbeih, M.D. [2]; Kashish Goel,M.D.

Pre-operative cardiac risk assessment Microchapters
Stepwise approach to preoperative cardiac assessment
Estimated energy requirements for various activities
Cardiac risk stratification for noncardiac surgical procedures
ACC / AHA recommendations for perioperative cardiac assessment
Preoperative cardiac risk assessment On the Web

Stepwise approach to preoperative cardiac assessment

Adapted from Fleisher et al. Circulation. 2009 Nov 24;120(21):e169-276; HR, Heart rate

^§,∧ Noninvasive testing is not useful for patients with no clinical risk factors undergoing intermediate-risk or low-risk noncardiac surgery (AHA guidelines Class III, Level of Evidence: C).

^¶ Clinical risk factors: Ischemic heart disease, compensated or prior heart failure, diabetes mellitus, renal insufficiency, and cerebrovascular disease

Active Cardiac conditions^*

1. Unstable coronary syndromes

• Unstable or severe angina (Canadian Cardiovascular Society class III or IV): May include “stable” angina in patients who are unusually sedentary.
• Recent MI: Greater than 7 days, but less than or equal to 1 month (within 30 days)

2. Decompensated HF

• NYHA functional class IV
• Worsening or new-onset heart failure

3. Significant arrhythmias

• High-grade atrioventricular block
• Mobitz II atrioventricular block
• Third-degree atrioventricular heart block
• Symptomatic ventricular arrhythmias
• Supraventricular arrhythmias (including atrial fibrillation) with uncontrolled ventricular rate (HR greater than 100 bpm at rest)
• Symptomatic bradycardia
• Newly recognized ventricular tachycardia

4. Severe valvular disease

• Severe aortic stenosis (mean pressure gradient >40 mm Hg, aortic valve area <1.0 cm2, or symptomatic)
• Symptomatic mitral stenosis (progressive dyspnea on exertion, exertional presyncope, or heart failure)

Estimated energy requirements for various activities^#

The metabolic equivalent of task (MET), or simply metabolic equivalent, is a physiological concept expressing the energy cost of physical activities as multiples of resting metabolic rate (RMR) and is defined as the ratio of metabolic rate (and therefore the rate of energy consumption) during a specific physical activity to a reference rate of metabolic rate at rest, set by convention to 3.5 ml O2·kg-1·min-1 or equivalently 1 kcal·kg-1· h-1 or 4.184 kJ·kg-1· h-1. By convention 1 MET is considered as the resting metabolic rate obtained during quiet sitting . MET values of physical activities range from 0.9 (sleeping) to 18 (running at 17.5 km/h or a 5:31 mile pace).

Calculating the weekly energy expended in recreational-time physical activity using METs (Metabolic equivalent task) .

Physical Activity	MET
Light Intensity Activities	< 3
sleeping	0.9
watching television	1.0
writing, desk work, typing	1.8
walking, 1.7 mph (2.7 km/h), level ground, strolling, very slow	2.3
walking, 2.5 mph (4 km/h)	2.9
Moderate Intensity Activities	3 to 6
bicycling, stationary, 50 watts, very light effort	3.0
walking 3.0 mph (4.8 km/h)	3.3
calisthenics, home exercise, light or moderate effort, general	3.5
walking 3.4 mph (5.5 km/h)	3.6
bicycling, <10 mph (16 km/h), leisure, to work or for pleasure	4.0
bicycling, stationary, 100 watts, light effort	5.5
Vigorous Intensity Activities	> 6
jogging, general	7.0
calisthenics (e.g. pushups, situps, pullups,jumping jacks), heavy, vigorous effort	8.0
running jogging, in place	8.0
rope jumping	10.0

Cardiac risk stratification for noncardiac surgical procedures

High (Reported cardiac risk often greater than 5%)

• Aortic and other major vascular surgery.
• Peripheral vascular surgery.
• Anticipated prolonged surgical procedures associated with large fluid shifts and/or blood loss.

Intermediate (Reported cardiac risk generally 1% to 5%)

• Carotid endarterectomy.
• Head and neck surgery.
• Intraperitoneal and intrathoracic surgery.
• Orthopedic surgery.
• Prostate surgery.

Low (Reported cardiac risk generally less than 1%)

• Endoscopic procedures.
• Superficial procedure.
• Cataract surgery.
• Breast surgery.

• Ambulatory surgery

ACC / AHA recommendations for perioperative cardiac assessment

This table below contains the ACC/AHA 2007 guidelines on perioperative cardiovascular evaluation and care for noncardiac surgery.

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Class I Patients who have a need for emergency noncardiac surgery should proceed to the operating room and continue perioperative surveillance and postoperative risk :stratification and risk factor management. (Level of Evidence: C) Patients with active cardiac conditions* should be evaluated and treated per ACC/AHA guidelines and, if appropriate, consider proceeding to the operating room. (Level of Evidence: B) Patients undergoing low risk surgery are recommended to proceed to planned surgery.† (Level of Evidence: B) Patients with poor (less than 4 METs) or unknown functional capacity and no clinical risk factors should proceed with planned surgery.† (Level of Evidence: B) Class IIa It is probably recommended that patients with functional capacity greater than or equal to 4 METs without symptoms‡ proceed to planned surgery.§ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for vascular surgery consider testing if it will change management.¶ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for intermediate risk surgery proceed with planned surgery with heart rate control.¶ (Level of Evidence: B) It is probably recommended that patients with poor (less than 4 METs) or unknown functional capacity and 1 or 2 clinical risk factors who are scheduled for vascular or intermediate risk surgery proceed with planned surgery with heart rate control.¶ (Level of Evidence: B) Class IIb Noninvasive testing might be considered if it will change management for patients with poor (less than 4 METs) or unknown functional capacity and 3 or more clinical risk factors who are scheduled for intermediate risk surgery. (Level of Evidence: B) Noninvasive testing might be considered if it will change management for patients with poor (less than 4 METs) or unknown functional capacity and 1 or 2 clinical risk factors who are scheduled for vascular or intermediate risk surgery. (Level of Evidence: B) §Noninvasive testing may be considered before surgery in specific patients with risk factors if it will change management. Clinical risk factors include ischemic heart disease, compensated or prior heart failure, diabetes mellitus, renal insufficiency, and cerebrovascular disease. ¶Consider perioperative beta blockade (see Table 12) for populations in which this has been shown to reduce cardiac morbidity/mortality.

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References

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