Document Detail


QT dynamics early after exercise as a predictor of mortality.
MedLine Citation:
PMID:  20478405     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
BACKGROUND: Exercise and QT dynamics during ambulatory monitoring impact mortality in a variety of populations. Heart rate recovery (HRR) after exercise is a known strong predictor of mortality.
OBJECTIVE: This study assessed the independent prognostic significance of the QT response to changing heart rate (QT dynamics) during recovery from exercise.
METHODS: The cohort included patients referred for treadmill exercise stress testing over a 5-year period. Patients had to have at least 4 electrocardiographic tracings within 5 minutes of peak exercise. One had to be recorded 60 seconds into recovery to calculate the HRR. Linear regression of the QT-RR relation during recovery was used to predict the QT interval at cycle lengths of 500 and 600 ms (QT-500 and QT-600). Only studies with an R(2) > or = 0.9 (72%) were retained. Optimal binary cut points were chosen. All-cause mortality was determined from either the Social Security Death Index or hospital records.
RESULTS: A total of 2,994 patients met inclusion criteria; 228 (7.6%) died during an average follow-up of 7.6 +/- 1.9 years. Abnormal QT-500 (>316 ms) was the strongest univariate QT dynamics predictor in a Cox proportional hazards model (hazard ratio = 2.13, P <.001). It remained an independent predictor of mortality after adjustment for age, exercise capacity, medications, single photon emission computed tomography defects, and abnormal (<12 beats/min) HRR (hazard ratio = 1.46, P = .014).
CONCLUSION: An abnormal predicted QT interval at 500 ms (120 beats/min) during recovery from exercise independently predicts all-cause mortality. Because QT dynamics in recovery incorporate information on both repolarization and autonomic responsiveness, its role in risk prediction for sudden cardiac death should be further explored.
Authors:
Nils P Johnson; Thomas A Holly; Jeffrey J Goldberger
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural     Date:  2010-05-15
Journal Detail:
Title:  Heart rhythm : the official journal of the Heart Rhythm Society     Volume:  7     ISSN:  1556-3871     ISO Abbreviation:  Heart Rhythm     Publication Date:  2010 Aug 
Date Detail:
Created Date:  2010-07-26     Completed Date:  2010-12-15     Revised Date:  2013-05-29    
Medline Journal Info:
Nlm Unique ID:  101200317     Medline TA:  Heart Rhythm     Country:  United States    
Other Details:
Languages:  eng     Pagination:  1077-84     Citation Subset:  IM    
Copyright Information:
Copyright 2010 Heart Rhythm Society. Published by Elsevier Inc. All rights reserved.
Affiliation:
Division of Cardiology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, USA.
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MeSH Terms
Descriptor/Qualifier:
Adaptation, Physiological
Aged
Death, Sudden, Cardiac* / etiology
Electrocardiography*
Exercise Test*
Exercise Tolerance / physiology*
Female
Heart Rate*
Humans
Kaplan-Meier Estimate
Male
Middle Aged
Predictive Value of Tests
Risk Factors
Stress, Physiological
Grant Support
ID/Acronym/Agency:
1 RO1 HL 70179-01A2/HL/NHLBI NIH HHS; R01 HL070179-04/HL/NHLBI NIH HHS
Comments/Corrections
Erratum In:
Heart Rhythm. 2010 Nov;7(11):1724

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


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