PMID- 19647268
OWN - NLM
STAT- MEDLINE
DCOM- 20100127
LR  - 20091026
IS  - 1532-8430 (Electronic)
IS  - 0022-0736 (Linking)
VI  - 42
IP  - 6
DP  - 2009 Nov-Dec
TI  - 24-hour QT variability in heart failure.
PG  - 500-4
LID - 10.1016/j.jelectrocard.2009.06.021 [doi]
AB  - BACKGROUND: Previous studies have shown that increased temporal variability of 
      repolarization, as reflected by QT interval variability measured for 10 minutes, 
      predicted spontaneous ventricular arrhythmias in implantable cardioverter 
      defribrillator patients, but it is unclear how these measures perform in 24-hour 
      recordings. METHODS: Twenty-four-hour digital Holter recordings from 372 subjects 
      with chronic heart failure enrolled in Gruppo Italiano per lo Studio della 
      Sopravvivenza nell'Insufficienza Cardiaca, (GISSI) Heart Failure study were 
      analyzed using a template-matching, semiautomatic algorithm to measure QT and 
      heart rate time series in sequential 5-minute epochs for 24 hours. QT variability 
      was expressed as normalized QT variance (QTVN) or as the log ratio of the QTVN 
      over normalized heart rate variance (QT variability index, or QTVI). RESULTS: A 
      pronounced diurnal variation was seen in both QTVI and QTVN. Both were lowest in 
      the midnight to 6 am time frame and increased throughout the day, peaking at noon 
      to 6 pm, then decreasing 6 pm to midnight. For QTVI, all 4 time points were 
      significantly different (P < .0001). QT variability index correlated with heart 
      rate (r = 0.38, P < .0001) and was significantly higher for those in higher New 
      York Heart Association (NYHA) classes (r = 0.22, P = .0003). Normalized QT 
      variance did not correlate with heart rate or NYHA but correlated negatively with 
      serum potassium (r = -0.22, P = .0002) and manifested the greatest increase 
      during midmorning hours. CONCLUSIONS: Repolarization lability as reflected in QT 
      variability has a pronounced diurnal variation and increases significantly after 
      6 am, the time of greatest arrhythmic risk. QT variability for 24 hours might 
      improve risk prediction in chronic heart failure patients and should be tested in 
      appropriate trials.
FAU - Dobson, Craig P
AU  - Dobson CP
AD  - Children's National Medical Center, Washington, DC, USA.
FAU - La Rovere, Maria Teresa
AU  - La Rovere MT
FAU - Olsen, Cara
AU  - Olsen C
FAU - Berardinangeli, Marino
AU  - Berardinangeli M
FAU - Veniani, Marco
AU  - Veniani M
FAU - Midi, Paolo
AU  - Midi P
FAU - Tavazzi, Luigi
AU  - Tavazzi L
FAU - Haigney, Mark
AU  - Haigney M
CN  - GISSI-HF Investigators
LA  - eng
PT  - Journal Article
DEP - 20090731
PL  - United States
TA  - J Electrocardiol
JT  - Journal of electrocardiology
JID - 0153605
SB  - IM
MH  - Adult
MH  - Aged
MH  - Aged, 80 and over
MH  - Arrhythmias, Cardiac/*complications/*diagnosis
MH  - Electrocardiography, Ambulatory/*methods
MH  - Female
MH  - Heart Failure/*complications/*diagnosis
MH  - *Heart Rate
MH  - Humans
MH  - Male
MH  - Middle Aged
MH  - Reproducibility of Results
MH  - Sensitivity and Specificity
EDAT- 2009/08/04 09:00
MHDA- 2010/01/28 06:00
CRDT- 2009/08/04 09:00
PHST- 2009/04/11 00:00 [received]
PHST- 2009/08/04 09:00 [entrez]
PHST- 2009/08/04 09:00 [pubmed]
PHST- 2010/01/28 06:00 [medline]
AID - S0022-0736(09)00266-0 [pii]
AID - 10.1016/j.jelectrocard.2009.06.021 [doi]
PST - ppublish
SO  - J Electrocardiol. 2009 Nov-Dec;42(6):500-4. doi: 
      10.1016/j.jelectrocard.2009.06.021. Epub 2009 Jul 31.