X. EXERCISE STRESS TEST
• Inadequate blood pressure response or inadequate heart rate response (chronotropic incompetence); blood pressure and heart rate should increase
• Presence of ventricular arrhythmias
During the recovery phase important information may be obtained to point to the diagnosis of ischemic heart disease, and this could be most useful when testing if the exercise phase reveals no abnormalities. Diagnostic points include ST segment depression greater than 1 mm and delayed slowing of the heart rate.
Monitoring of the heart rate during the recovery period adds substantially to the value of exercise stress testing. Studies indicate that a delay in the decrease in the heart rate after exercise may result from inadequate reactiva¬tion of vagal tone. This predicts a poor outcome with a quadrupling of the risk of death over the next six years. The rate at which the heart rate decreases after exercise is a reflection of the level of the individual’s level of physical fitness.
The appearance of high-grade ventricular arrhythmias during the recovery time appears to predict subsequent mortality better than the occurrence of ventricular arrhy¬thmias during exercise. The appearance of ventricular arrhythmias during recovery appears to be due to inade¬quate vagal reactivation. Figure 4 shows the electrocardio¬graphic tracings from a patient before, during. and after exercise with the presence of delayed slowing of the heart rate and a malignant ventricular arrhythmia. XI. CONCLUSION