Affiliation:
1. Department of Cardiovascular Sciences, University of Leuven, Belgium
2. Department of Cardiology, University Hospitals Leuven, Leuven, Belgium
3. Department of Pharmaceutical and Pharmacological Sciences, University of Leuven, Belgium
4. Department of Neurosciences, University of Leuven, Belgium
Abstract
Background
Drug safety precautions recommend monitoring of the corrected
QT
interval. To determine which
QT
correction formula to use in an automated
QT
‐monitoring algorithm in our electronic medical record, we studied rate correction performance of different
QT
correction formulae and their impact on risk assessment for mortality.
Methods and Results
All electrocardiograms (
ECG
s) in patients >18 years with sinus rhythm, normal
QRS
duration and rate <90 beats per minute (bpm) in the University Hospitals of Leuven (Leuven, Belgium) during a 2‐month period were included.
QT
correction was performed with Bazett, Fridericia, Framingham, Hodges, and Rautaharju formulae. In total, 6609 patients were included (age, 59.8±16.2 years; 53.6% male and heart rate 68.8±10.6 bpm). Optimal rate correction was observed using Fridericia and Framingham; Bazett performed worst. A healthy subset showed 99% upper limits of normal for Bazett above current clinical standards: men 472 ms (95%
CI
, 464–478 ms) and women 482 ms (95%
CI
474–490 ms). Multivariate Cox regression, including age, heart rate, and prolonged
QT
c, identified Framingham (hazard ratio [
HR
], 7.31; 95%
CI
, 4.10–13.05) and Fridericia (
HR
, 5.95; 95%
CI
, 3.34–10.60) as significantly better predictors of 30‐day all‐cause mortality than Bazett (
HR
, 4.49; 95%
CI
, 2.31–8.74). In a point‐prevalence study with haloperidol, the number of patients classified to be at risk for possibly harmful
QT
prolongation could be reduced by 50% using optimal
QT
rate correction.
Conclusions
Fridericia and Framingham correction formulae showed the best rate correction and significantly improved prediction of 30‐day and 1‐year mortality. With current clinical standards, Bazett overestimated the number of patients with potential dangerous
QT
c prolongation, which could lead to unnecessary safety measurements as withholding the patient of first‐choice medication.
Publisher
Ovid Technologies (Wolters Kluwer Health)
Subject
Cardiology and Cardiovascular Medicine
Cited by
309 articles.
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