A method for treating acute coronary syndromes (i.e., unstable angina or non-Q-wave MI) or transient ischemic attacks in a human or animal patient by placing a heat exchange apparatus in the patient's vasculature and using that heat exchange apparatus to cool the patient to a temperature (e.g. 30-36 degrees C.) at which platelet inhibition (i.e., inhibition of platelet activation and/or aggregation and/or adhesion) occurs. Anti-shivering drugs or anesthesia may be administered to patients whose body temperature is cooled below that patient's shivering threshold (typically approximately 35.5 degrees C.). If it is determined that platelet inhibition is no longer desirable, such as when the patient is about to undergo a surgical or interventional procedure wherein bleeding could be problematic, the hypothermia-induced platelet inhibition may be rapidly reversed by using the intravascular heat exchange apparatus to re-warm the patient's body to normothermia or near normothermia.