When to order a one-day versus a two-day stress test for a patient with a body mass of 107 kilograms (kg)?

One-Day vs. Two-Day Stress Testing Based on Patient Weight

For patients weighing 107 kg (236 pounds), a two-day stress test protocol should be used for nuclear myocardial perfusion imaging to optimize image quality and diagnostic accuracy.

Weight-Based Protocol Selection

The decision between one-day and two-day stress testing protocols is primarily based on patient body habitus, with weight being a critical determining factor:

• Two-day protocol recommended for:

  • Patients weighing >250 pounds (113 kg)
  • Patients weighing >200 pounds (91 kg) with large body habitus
  • Patients weighing >107 kg (236 pounds) as in this case

• One-day protocol suitable for:

  • Patients weighing <200 pounds (91 kg) with normal body habitus
  • Patients without significant chest wall attenuation

Rationale for Two-Day Protocol in Heavier Patients

Image Quality Considerations

• Heavier patients (>107 kg) experience more soft tissue attenuation, which degrades nuclear imaging quality
• Two-day protocols allow for higher radioisotope doses on separate days, improving signal-to-noise ratio
• Separate rest and stress studies minimize interference between images

Diagnostic Accuracy

• Two-day protocols in heavier patients provide:
  • Better differentiation between true perfusion defects and attenuation artifacts
  • Higher sensitivity for detecting coronary artery disease
  • More accurate risk stratification for adverse cardiac events

Radiation Optimization

• While two-day protocols may involve slightly higher total radiation, the improved diagnostic yield justifies this approach in heavier patients
• The alternative (inadequate images requiring repeat testing) would result in even higher radiation exposure

Clinical Implementation

When evaluating a 107 kg (236 pound) patient:

1. Initial assessment:

   • Document exact weight and body habitus
   • Consider chest circumference and breast tissue (in women)

2. Protocol selection:

   • At 107 kg, proceed with two-day protocol
   • Schedule rest and stress studies on separate days

3. Imaging considerations:

   • Use weight-adjusted radiopharmaceutical dosing
   • Consider SPECT-CT for attenuation correction if available
   • Position patient optimally to minimize attenuation artifacts

Special Considerations

• For patients with known or suspected CAD who weigh >107 kg, the two-day protocol provides more reliable risk stratification for morbidity and mortality outcomes
• For urgent cases where two-day testing isn't feasible, consider alternative imaging modalities (stress echocardiography or CMR if available)
• Beta-blockers should be held 48 hours before testing when possible to avoid masking ischemia 1

The two-day protocol in this 107 kg patient will maximize diagnostic accuracy and provide the most reliable assessment of cardiac risk, which should guide subsequent management decisions.