Pharmacologic Stress Testing

Cardiac stress testing is the most commonly used modality for diagnostic purposes in patients with known or suspected coronary artery disease (CAD). The utility of stress testing should be interpreted based on the likelihood of the disease. Patients with a low probability of disease have a high risk of false-positive results and may end up further unnecessary invasive testing without changing patient outcomes. Those with high pretest probability have a high risk of false-negative results that can miss a critical diagnosis; therefore, these patients should proceed directly to more confirmatory testing such as cardiac catheterization.Stress testing is most clinically useful in intermediate-risk patients for CAD that will help further reclassify these patients into low risk and high-risk depending on the stress test result. Stress testing can also be used to obtain prognostic information to determine the patient's response to optical medical therapy, measure exercise capacity, evaluate ischemia who are already started on medical therapy for known CAD. In general exercise, stress is preferred because it provides a gauge of functional capacity, exercise tolerance, and symptom provocation. Pharmacologic stress testing is an alternative modality in patients who are unable to exercise and with the following conditions: Patients presenting with unstable angina. History of heart failure which is not well controlled, and there is a concern for deterioration. Poorly controlled blood pressure with systolic blood pressure significantly higher (>200 mmHg at rest). Patients with a history of aortic stenosis which is significantly worse on echocardiogram (aortic valve area 40 mmHg) and have ongoing symptoms. Myocardial infarction in the last week. Acute pulmonary embolism Acute inflammation of pericardium or myocardium Severe pulmonary hypertension Exercise stress testing is also not very helpful in patients with an insufficient hemodynamic response to exercise due to abnormalities involving the respiratory system, and having ongoing issues involving muscles, bones, and vessels in the peripheral system. Also, the exercise stress test is not useful when baseline EKG is abnormal such as with left ventricular hypertrophy (LVH), left bundle branch block (LBBB), paced rhythm, Wolff Parkinson White (WPW) syndrome, or greater than 1 mm ST-segment depression. These patients are suitable candidates for testing involving pharmacologic agents. Pharmacologic stress testing is used in combination with imaging modalities such as radionuclide imaging and echocardiography.