Related Experiment Videos
Optimal target heart rate for exercise-induced T-wave alternans.
G Turitto1, E B Caref, G El-Attar
1Department of Medicine, State University of New York -- Downstate Medical Center and Veterans Affairs Medical Center, Brooklyn, NY 11203, USA. gturitto@aol.com
Summary
A target heart rate (HR) of 115 beats/min effectively identifies exercise-induced T-wave alternans (TWA) risk for malignant ventricular tachyarrhythmias. However, some patients may not reach this HR, necessitating further evaluation.
Area of Science:
- Cardiology
- Electrophysiology
- Exercise Physiology
Background:
- T-wave alternans (TWA) indicates vulnerability to ventricular tachyarrhythmias.
- False positive TWA can occur in healthy individuals at high heart rates (HR).
Purpose of the Study:
- Determine the optimal target HR for exercise-induced TWA detection.
- Assess TWA as a risk index for malignant ventricular tachyarrhythmias.
Main Methods:
- Evaluated 50 patients with malignant ventricular tachyarrhythmias (Group I) and 55 healthy controls (Group II).
- Assessed TWA during symptom-limited bicycle exercise tests in both groups.
- Analyzed HR at TWA onset and receiver operating characteristic (ROC) curves.
Main Results:
- A HR of 115 beats/min demonstrated 100% sensitivity and 96% specificity for TWA.
- Patients with malignant arrhythmias had TWA at lower HRs compared to controls.
- A significant number of patients could not achieve the target HR for testing.
Conclusions:
- A target HR of 115 beats/min is optimal for exercise-induced TWA to identify arrhythmia risk.
- Inability to reach target HR may lead to indeterminate test results.
- Pharmacologic testing may be valuable for patients unable to achieve target HR.