Cardiac Stress Imaging

CARDIOLOGY

Indications for Stress Imaging

Use imaging if the ECG is uninterpretable. EGC may be uninterpretable in the following cases.

  • pacing,
  • LBBB,
  • resting ST depressions > 1mm,
  • digoxin,
  • LVH,
  • WPW
  • After an indeterminate ECG test,
  • Pharmacologic tests
  • Localization of ischemia.

Stress imaging modalities

  1. Radionuclide stress myocardial perfusion imaging (MPI) — Radionuclide stress MPI using single photon emission computed tomography (SPECT) and positron emission tomography (PET) are used in the diagnosis, risk stratification, and guidance of therapy in patients with suspected or known CHD. SPECT MPI agents are technetium-99m based (Tc-99m sestamibi and Tc-99m tetrofosmin). PET MPI agents include rubidium-82 andN13-ammonia. SPECT may be used with Exercise or pharmacologic stress while PET is usually used with pharmacologic stress alone because of short physical half-lives of PET tracers that makes pharmacologic vasodilators the preferred stress method over exercise.
  2. Stress echocardiography. Stress (exercise or pharmacologic) transthoracic echocardiography (TTE) is used to detect hemodynamically significant CHD, localize ischemia in patients with known CHD, risk stratify patients, and assess for valvular disease and myocardial viability.  You detect ischemia by looking for the development of new regional wall motion abnormalities or worsening of preexisting regional wall motion abnormalities.
  3. Stress cardiovascular MRI = Cardiovascular Magnetic Resonance (CMR) imaging. It provides information on the heart structure; global and regional left and right ventricular function; infarct size, location, and transmurality; and myocardial perfusion through pharmacologic stress.
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