Slow QT Interval Adaptation to Heart Rate Changes in Normal Ambulatory Subjects

Eathar Razak; Marie Buncová; Vladimir Shusterman; Bruce Winter; Win-Kuang Shen; Michael J Ackerman; Theresa Donovan; Rachel Lampert; Jan Němec

doi:10.1111/j.1542-474X.2011.00420.x

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Slow QT Interval Adaptation to Heart Rate Changes in Normal Ambulatory Subjects

Journal article

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Slow QT Interval Adaptation to Heart Rate Changes in Normal Ambulatory Subjects

Eathar Razak, Marie Buncová, Vladimir Shusterman, Bruce Winter, Win-Kuang Shen, Michael J Ackerman, Theresa Donovan, Rachel Lampert and Jan Němec

Annals of noninvasive electrocardiology, Vol.16(2), pp.148-155

04/2011

DOI: 10.1111/j.1542-474X.2011.00420.x

PMCID: PMC6931985

PMID: 21496165

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Abstract

Background: Clinical formulas for QT correction utilize instantaneous HR. We showed previously that longer-term HR affects QT duration. We extend these findings, identifying more accurate models of QT behavior. Method: Multiple models of QT dependence on HR were tested in 2 independent populations. Holter recordings were analyzed in population A (healthy volunteers, n = 14, 6 males, age 26.9 ± 12.3 yr). The hypotheses generated in population A were tested in an independent group population B, healthy volunteers, n = 15, 9 males, age 52.9 ± 15.6 yr). Linear models of QT interval dependence on a weighted average of RR intervals in the preceding 3 minutes were compared to models based on the immediately preceding RR interval (instantaneous HR). Results: In population A, linear models based on RR intervals over the preceding minute performed better than the best nonlinear model based on the single RR interval immediately preceding the QT interval. Linear models including HR values preceding the QT interval by more than 60 s further improved model fit. This model hierarchy was confirmed in population B. Linear formula for QT correction based on exponential decay of HR effect with 60 s time constant outperformed Bazett and Fridericia formulas in both populations. Conclusions: QT duration in normal ambulatory subjects is affected by noninstantaneous HR, including HR history dating back more than 60 s. Exponential decay of this "memory effect" with time constant of 1 minute provides an accurate description of QT adaptation. This may be of clinical importance when HR is not steady.

QT interval correction

ambulatory ECG

QT interval adaptation

Details

Title: Subtitle: Slow QT Interval Adaptation to Heart Rate Changes in Normal Ambulatory Subjects
Creators: Eathar Razak - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Marie Buncová - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Vladimir Shusterman - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Bruce Winter - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Win-Kuang Shen - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Michael J Ackerman - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Theresa Donovan - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Rachel Lampert - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Jan Němec - From the University of Pittsburgh, Pittsburgh, PA; †Institute for Clinical and Experimental Medicine, Prague, Czech Republic; ‡Mayo Clinic, Rochester, MN; §Yale University, New Haven, CT
Resource Type: Journal article
Publication Details: Annals of noninvasive electrocardiology, Vol.16(2), pp.148-155
Publisher: Blackwell Publishing Inc
DOI: 10.1111/j.1542-474X.2011.00420.x
PMID: 21496165
PMCID: PMC6931985
ISSN: 1082-720X
eISSN: 1542-474X
Number of pages: 8
Language: English
Date published: 04/2011
Academic Unit: Cardiovascular Medicine; Internal Medicine
Record Identifier: 9984094378802771

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