In an otherwise healthy obese patient undergoing low- to moderate-risk surgery, should a preoperative electrocardiogram (ECG) be performed solely because of obesity?

Should You Do ECG on Preop Just for Obesity?

No, a preoperative ECG should not be performed solely because of obesity in an otherwise healthy patient undergoing low- to moderate-risk surgery. The decision to obtain a preoperative ECG depends on the presence of cardiovascular risk factors, symptoms, known cardiovascular disease, and the surgical risk level—not obesity alone. 1

Risk-Stratified Approach to Preoperative ECG

Low-Risk Surgery

• Routine preoperative ECG is not recommended for asymptomatic patients undergoing low-risk surgical procedures (expected <1% 30-day major adverse cardiac event risk), regardless of obesity status. 1
• This recommendation holds even for obese patients, as routine testing in low-risk situations does not improve outcomes and can lead to unnecessary delays. 2

Intermediate- to High-Risk Surgery

The decision for preoperative ECG in obese patients undergoing elevated-risk surgery should be based on:

Indications for ECG (Class IIa - Reasonable): 1

• Known coronary heart disease
• Significant arrhythmia history
• Peripheral arterial disease
• Cerebrovascular disease
• Structural heart disease
• Active cardiovascular symptoms (chest pain, dyspnea, undiagnosed palpitations, tachycardia, syncope, or murmurs)

May Consider ECG (Class IIb): 1

• Asymptomatic patients undergoing elevated-risk surgeries without known CVD (to establish baseline and guide perioperative management)

Special Considerations in Obesity

Why Obesity Alone Is Insufficient Justification

While obesity is associated with numerous cardiovascular comorbidities, the physical examination and ECG often underestimate cardiac dysfunction in obese patients. 1 However, this does not justify routine ECG screening. Instead, focus on:

Key obesity-related comorbidities that warrant ECG: 1

• Atherosclerotic cardiovascular disease
• Heart failure
• Systemic hypertension
• Cardiac arrhythmias (particularly atrial fibrillation)
• Poor exercise capacity (<4 METs)

Evidence Against Routine Testing in Obesity

A study of 193 morbidly obese patients undergoing weight loss surgery found that preoperative ECG identified abnormalities in 15% of patients, but none required preoperative intervention. 3 The study concluded that routine preoperative ECG is not mandatory and should be used selectively based on medical history. 3

Similarly, research on preoperative evaluation in elective non-cardiac surgery emphasizes that ECG is not mandatory even for intermediate-risk surgeries if the patient is asymptomatic, has good functional capacity, and has no pre-existing heart disease. 2

Clinical Algorithm for Decision-Making

Step 1: Assess Surgical Risk

• Low-risk surgery (<1% MACE risk): No ECG needed 1
• Intermediate/high-risk surgery: Proceed to Step 2

Step 2: Evaluate for Cardiovascular Disease or Symptoms

• If YES to any of the following, obtain ECG: 1
  • Known cardiovascular disease
  • Active cardiac symptoms
  • History of arrhythmias
  • Peripheral/cerebrovascular disease
• If NO to all above: ECG may be considered but is not mandatory 1

Step 3: Consider Additional Risk Factors in Obese Patients

• Age >45 years 4, 5
• History of cardiac disease 3
• Diabetes mellitus 5
• Chronic kidney disease 5
• ASA classification III-V 5

Important Caveats

ECG Abnormalities in Obesity

Obesity is associated with various ECG changes including leftward axis shifts, low QRS voltage, left ventricular hypertrophy markers, T-wave flattening, and QT prolongation. 6 Many of these abnormalities are reversible with weight loss and do not necessarily indicate pathology requiring intervention. 6

Baseline ECG Value

If an ECG is obtained, it serves as a valuable baseline for comparison should postoperative complications develop, particularly in patients undergoing elevated-risk procedures. 1 Recognition of prolonged QT interval may inform selection of anesthetics, antiemetics, or antibiotics. 1

Medicolegal Considerations

In practice settings where there is pressure to order extensive preoperative investigations, adhering to guideline-driven protocols establishes a clear standard of care. 2 Documenting the rationale for selective testing (or omission) per accepted guidelines protects clinicians from medicolegal concerns while focusing resources on truly at-risk patients. 2

What NOT to Do

• Do not obtain routine ECG in asymptomatic obese patients undergoing low-risk surgery 1
• Do not use obesity alone as an indication for preoperative ECG 4, 3
• Do not order ECG without considering the patient's functional capacity, symptoms, and surgical risk 2