Professional
Technical
IVT
chronotropic index
A measure of heart rate response to exercise, calculated as percentage of age-predicted maximum heart rate achieved.
Full Definition
The chronotropic index quantifies the adequacy of heart rate response during exercise testing in cardiac rehabilitation patients. It is calculated as the ratio of heart rate reserve used to metabolic reserve used, typically expressed as a percentage. A chronotropic index below 80% may indicate chronotropic incompetence, which affects exercise prescription and prognosis. This measurement is particularly important for patients on beta-blockers or those with conduction system abnormalities.
Usage
Usage note: Distinguish from chronotropic incompetence, which is a diagnosis based on low chronotropic index.
In Context
- "The patient demonstrated a chronotropic index of 75%, suggesting mild chronotropic incompetence." — Exercise test interpretation
- "Chronotropic index assessment revealed normal heart rate response to exercise despite beta-blocker therapy." — Cardiopulmonary exercise test report
Also known as
CI
heart rate response index
Don't confuse with
chronotropic incompetence
heart rate reserve