A cardiac stress test (also referred to as a cardiac diagnostic test, cardiopulmonary exercise test, or abbreviated CPX test) is a cardiological test that measures the hearts ability to respond to external stress in a controlled clinical environment. The stress response is induced by exercise or by intravenous pharmacological stimulation. Cardiac stress tests compare the coronary circulation while the patient is at rest with the same patients circulation during maximum cardiac exertion, showing any abnormal blood flow to the myocardium (heart muscle tissue). The results can be interpreted as a reflection on the general physical condition of the test patient. This test can be used to diagnose coronary artery disease (also known as ischemic heart disease) and assess patient prognosis after a myocardial infarction (heart attack). Exercise-induced stressors are most commonly either exercise on a treadmill or pedalling a stationary exercise bicycle ergometer. The level of stress is progressively increased by raising the difficulty (steepness of the slope on a treadmill or resistance on an ergometer) and speed. People who cannot use their legs may exercise with a bicycle-like crank that they turn with their arms, or may be given a medication to induce cardiac stress. Once the stress test is completed, the patient generally is advised to not suddenly stop activity but to slowly decrease the intensity of the exercise over the course of several minutes. The test administrator or attending physician examines the symptoms and blood pressure response.
Unless high-risk markers are present, such as diabetes in patients aged over 40, peripheral arterial disease; or a risk of coronary heart disease greater than 2 percent yearly, most health societies do not recommend the test as a routine procedure.Absolute contraindications to cardiac stress test include:

Acute myocardial infarction within 48 hours
Unstable angina not yet stabilized with medical therapy
Uncontrolled cardiac arrhythmia, which may have significant hemodynamic responses (e.g. ventricular tachycardia)
Severe symptomatic aortic stenosis, aortic dissection, pulmonary embolism, and pericarditis
Multivessel coronary artery diseases that have a high risk of producing an acute myocardial infarction
Decompensated or inadequately controlled congestive heart failure
Uncontrolled hypertension (blood pressure>200/110mm Hg)
Severe pulmonary hypertension
Acute aortic dissection
Acutely ill for any reasonIndications for termination:
A cardiac stress test should be terminated before completion under the following circumstances:Absolute indications for termination include:

Systolic blood pressure decreases by more than 10 mmHg with increase in work rate, or drops below baseline in the same position, with other evidence of ischemia. Increase in nervous system symptoms: Dizziness, ataxia or near syncope
Moderate to severe anginal pain (above 3 on standard 4-point scale)
Signs of poor perfusion, e.g. cyanosis or pallor
Request of the test subject
Technical difficulties (e.g. difficulties in measuring blood pressure or EGC)
ST Segment elevation of more than 1 mm in aVR, V1 or non-Q wave leads
Sustained ventricular tachycardiaRelative indications for termination include:

Systolic blood pressure decreases by more than 10 mmHg with increase in work rate, or drops below baseline in the same position, without other evidence of ischemia. ST or QRS segment changes, e.g.