Exercise testing for chronotropic assessment.

Cardiac chronotropic analysis has only begun to develop into a clinically relevant science. In the past, formal exercise testing was usually relegated to the assessment of ischemia or cardiac rehabilitation. The establishment of rate-responsive pacemakers as a potentially effective treatment for chronotropic incompetence forced the definition of cardiac chronotropism and assessment of the pacemaker response. Little is known about the normal chronotropic response and less has been established about patients with ventricular dysfunction or ischemia, but standards are being set and modern pacemakers have produced the ideal clinical laboratory for investigation. Advanced telemetry, including sensor and actual rate trends, histography and sensorgraphy produce previously unobtainable clinical data. Now scientific inquiry demands that chronotropic evaluations seek to match the pacemaker-augmented response of the chronotropically incompetent patient to the metabolic requirements of the body. Only with formal exercise testing will this goal be achieved.