# Suspicion of a myocardial infarction or acute myocardial infarction (heart attack) # Onset of moderate-to-severe angina (chest pain) # Drop in systolic blood pressure (SBP) below standing resting pressure or drop in SBP with increasing workload accompanied by signs or symptoms # Signs of poor perfusion (circulation or blood flow), including pallor (pale appearance to the skin), cyanosis (bluish discoloration), or cold and clammy skin

Severe or unusual shortness of breath # CNS (central nervous

system) symptoms ## e.g., ataxia (failure of muscular coordination), vertigo (An illusion of dizzying movement), visual or gait (pattern of walking or running) problems, confusion) # Serious arrhythmias (abnormal heart rhythms) ## e.g.: second / third degree AV block, atrial fibrillation with fast ventricular response, increasing premature ventricular contractions or sustained ventricular tachycardia) # Technical inability to monitor the ECG # Patient's request (to stop) # Any chest pain that is increasing # Physical or verbal manifestations of shortness of breath of severe fatigue # Wheezing # Leg cramps or intermittent claudication (grade 3 on a 4-point scale) # Hypertensive response (SBP >260 mm Hg; DBP>115 mm Hg) # Pronounced ECG changes from baseline ## >2 mm of horizontal or down sloping ST- segment depression, or >2 mm of ST-segment elevation (except in aVR) # Exercise-induced bundle branch block that cannot be distinguished from ventricular tachycardia # Less serious arrhythmias (abnormal heart rhythms) such as supraventricular tachycardia