Rate-corrected QT interval: Techniques and limitations

Funck‐Brentano, Christian; Jaillon, Patrice

doi:10.1016/0002-9149(93)90035-b

Cited by 374 publications

(235 citation statements)

References 40 publications

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“…Thus, further studies using prolonged administration of pyridostigmine are needed to determine whether QTc shortening Another issue is the use of Bazett's formula to calculate the QTc interval. There is a complex relationship between heart rate and the QT interval (19), making it impossible to propose a flawless method to correct the duration of ventricular repolarization for the underlying duration of the cardiac cycle. Some studies have investigated the relationship between parasympathetic stimulation and QT interval.…”

Section: Discussionmentioning

confidence: 99%

Cholinergic stimulation with pyridostigmine reduces the QTc interval in coronary artery disease

Castro

Porphirio²,

Serra³

et al. 2002

Braz J Med Biol Res

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Parasympathetic dysfunction is an independent risk factor in patients with coronary artery disease; thus, cholinergic stimulation is a potential therapeutic measure that may be protective by acting on ventricular repolarization. The purpose of the present study was to determine the effects of pyridostigmine bromide (PYR), a reversible anticholinesterase agent, on the electrocardiographic variables, particularly QTc interval, in patients with stable coronary artery disease. In a randomized double-blind crossover placebo-controlled study, simultaneous 12-lead electrocardiographic tracings were obtained at rest from 10 patients with exercise-induced myocardial ischemia before and 2 h after the oral administration of 45 mg PYR or placebo. PYR increased the RR intervals (pre: 921 ± 27 ms vs post: 1127 ± 37 ms; P<0.01) and, in contrast with placebo, decreased the QTc interval (pre: 401 ± 3 ms vs post: 382 ± 3 ms; P<0.01). No other electrocardiographic variables were modified (PR segment, QT interval, QT and QTc dispersions). Cholinergic stimulation with PYR caused bradycardia and reduced the QTc interval without important side effects in patients with coronary disease. These effects, if confirmed in studies over longer periods of administration, may suggest a cardioprotection by cholinergic stimulation with PYR. Correspondence

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Section: Discussionmentioning

confidence: 99%

Cholinergic stimulation with pyridostigmine reduces the QTc interval in coronary artery disease

Castro

Porphirio²,

Serra³

et al. 2002

Braz J Med Biol Res

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show abstract

“…The average QT interval duration was then corrected for heart rate by calculating QTc according to Bazett's equation (QTc¼QT interval duration/ (60/heart rate) 1/2 ). 19 Groups of participants defined by four QTc ranges (o400, 400-419, 420-439 and X440 ms) were used for the analysis.…”

Section: Measurements Of Qtcmentioning

confidence: 99%

QT interval prolongation and the risks of stroke and coronary heart disease in a general Japanese population: the Hisayama study

et al. 2010

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Uncertainty remains regarding the value of heart-rate-corrected QT interval (QTc) prolongation on electrocardiogram for predicting cardiovascular disease (CVD), particularly among Asian populations. The objective of the present analysis was to analyze the association of QTc prolongation with the development of CVD in a general Japanese population. During the follow-up period, 303 CVD events were observed. Among men, the age-adjusted incidence rates of CVD rose with prolonged QTc levels: 10.9, 12.1, 14.1 and 37.8 per 1000 person-years for subgroups defined by QTc levels of o400, 400-419, 420-439 and X440 ms, respectively (P¼0.0007 for trend). The risk of CVD in the highest group was 3.09-fold (95% confidence interval, 1.82-5.25) higher than that in the lowest group even after controlling for other confounding factors: age, hypertension, heart rate, electrocardiogram abnormalities, diabetes, impaired glucose tolerance, impaired fasting glycemia, body mass index, total and high-density lipoprotein cholesterols, alcohol intake, smoking habit and regular exercise. Similar associations were observed for the outcomes of stroke and coronary heart disease. Among women, in contrast, no clear associations were found between QTc levels and the risk of CVD events. In conclusion, prolonged QTc levels were associated with the development of CVD among general Japanese men. Measurement of QTc intervals is likely to provide additional information for the detection of individuals at high risk of future CVD events.

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“…A standard 12-lead EKG was recorded at a paper speed of 25 mdsecond with a calibration of 20 m d m V for 10 seconds. The QT interval was measured from the earliest onset of the QRS complex to the end of the T wave (14,27). The latter was identified where the downward slope of the T wave joins baseline.…”

Section: Ekg Interpretationmentioning

confidence: 99%

QTc Interval (Cardiac Repolarization): Lengthening After Meals

et al. 1997

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Weight reduction, either by dietary or surgical means, is associated with prolongation of the heart rate corrected QT interval (QTc=QT/R-R'*~) and, on occasion, sudden death. Screening subjects with obesity before weight loss for prolonged QTc intervals is an accepted practice, although at present, there are no guidelines for whether subjects should be fasting before electrocardiogram (EKG) evaluation. The aim of this study was to test the hypothesis that EKG QTc interval duration is independent of meal ingestion. The hypothesis was tested in 11 healthy subjects who ingested a 500-kcal formula meal. A small decrease in absolute QT interval and a steady decline in R-R interval were observed for up to 60 minutes after formula ingestion. The QTc interval increased above baseline at 15 minutes (p<0.007) after meal, a change that persisted for the 1-hour postmeal observation period. Spectral analysis of EKG R-R intervals (low-/high-frequency amplitude ratio) indicated a change in cardiac autonomic flow after meal ingestion. The QTc interval did not lengthen and R-R low-highfrequency amplitude ratio remained unchanged in eight subjects evaluated in a similar manner but in whom isovolumic amounts of water replaced the meal. These observations suggest that (1) cardiac repolarization changes with fasting and feeding, (2) the QTc interval is influenced by meal intake, and (3) the autonomic ner-GALLAGHER, ANGEL0 PIETROBELLI, ADRI- vous system may play a role in meal-related QTc changes. These findings have implications for the evaluation of patients with obesity before starting and during weight loss treatment.

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Rate-corrected QT interval: Techniques and limitations

Cited by 374 publications

References 40 publications

Cholinergic stimulation with pyridostigmine reduces the QTc interval in coronary artery disease

Cholinergic stimulation with pyridostigmine reduces the QTc interval in coronary artery disease

QT interval prolongation and the risks of stroke and coronary heart disease in a general Japanese population: the Hisayama study

QTc Interval (Cardiac Repolarization): Lengthening After Meals

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