Document Detail

Optimal target heart rate for exercise-induced T-wave alternans.
MedLine Citation:
PMID:  11333169     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: This study was conducted to determine the optimal target heart rate (HR) for the use of exercise-induced T-wave alternans (TWA) as an index for risk of malignant ventricular tachyarrhythmias. BACKGROUND: Rate-dependent TWA is an index of vulnerability to ventricular tachyarrhythmias. However, false positive TWA was reported to occur in normal subjects at high HR. METHODS: Two groups were evaluated: Group I: 50 patients with malignant ventricular tachyarrhythmias, who received an implantable cardioverter-defibrillator (ICD); and Group II: 55 age-matched normal subjects. In both Groups, TWA was evaluated during symptom-limited bicycle exercise test. RESULTS: Peak HR during exercise test was 103 +/- 17 beats/min in Group I, versus 124 +/- 18 beats/min in Group II (P < 0.001). In Group I, 4 patients were excluded from analysis, due to high noise level or frequent ectopy during exercise. Out of the remaining 46 patients, TWA was present in 28 patients (61%), and absent in 18 (39%). In group II, TWA was present in four subjects (7%), and absent in 51 (93%). HR at the onset of TWA was 91 +/- 11/min in Group I, and 119 +/- 12/min in Group II (P < 0.001). Receiver operated characteristics curves demonstrated that a HR of 115 beats/min was the cutoff with the best sensitivity and specificity for TWA (100 and 96%, respectively). None of the patients in Group I developed TWA at HR > 115 beats/min, while two out of four in Group II had TWA at HR > 115/minutes. However, 13 patients in Group I who had no TWA were unable to exercise to a peak HR > 115 beats/min, compared to nine subjects in Group II. CONCLUSIONS: A target HR of 115 beats/min was highly sensitive and specific for determination of exercise-induced TWA as an index of risk of malignant ventricular tachyarrhythmias. However, a significant number of patients may not be able to achieve this target HR, resulting in an indeterminate test. The value of pharmacologic testing in this group should be assessed.
G Turitto; E B Caref; G El-Attar; M Helal; A Mohamed; R P Pedalino; N El-Sherif
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Validation Studies    
Journal Detail:
Title:  Annals of noninvasive electrocardiology : the official journal of the International Society for Holter and Noninvasive Electrocardiology, Inc     Volume:  6     ISSN:  1082-720X     ISO Abbreviation:  Ann Noninvasive Electrocardiol     Publication Date:  2001 Apr 
Date Detail:
Created Date:  2001-05-02     Completed Date:  2001-07-26     Revised Date:  2008-03-10    
Medline Journal Info:
Nlm Unique ID:  9607443     Medline TA:  Ann Noninvasive Electrocardiol     Country:  United States    
Other Details:
Languages:  eng     Pagination:  123-8     Citation Subset:  IM    
Department of Medicine, State University of New York -- Downstate Medical Center and Veterans Affairs Medical Center, Brooklyn, NY 11203, USA.
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MeSH Terms
Aged, 80 and over
Case-Control Studies
Defibrillators, Implantable
Electrocardiography / methods*,  standards
Exercise Test / methods*,  standards
False Positive Reactions
Heart Rate*
Middle Aged
Risk Factors
Sensitivity and Specificity
Tachycardia, Ventricular / diagnosis*,  etiology*,  therapy

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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